JPH10200345A - Comparison device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To operate at 1.45 V or less by lowering the power supply voltage
To obtain a comparison device having a built-in reference voltage of 1.25 V or less and having small temperature dependency and having a hysteresis characteristic. A resistor connected to an input of a current mirror circuit is provided.
A first current divider 21 for flowing a current to a divided output of the first resistor voltage divider, and a second current connected to an input of a current mirror circuit. Generator 2
4, a resistor 32 connected to the output of the current mirror circuit,
33, a third current generator 31 for supplying a current to the divided output of the second resistor divider, and a fourth current generator connected to the output of the current mirror circuit. 34, and variable current generating means for outputting a first value or a second value in accordance with the output of the comparing means. The current values of the first and third current generating units Is controlled to have a magnitude proportional to the absolute temperature and inversely proportional to the current value setting resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current or voltage comparison device operating at a low power supply voltage, and more particularly to a comparison device which can arbitrarily set the temperature dependence of a reference voltage and hysteresis.

[0002]

2. Description of the Related Art Conventionally, such a comparison device has been disclosed in FIG.
There was something like that shown. FIG. 3 is a circuit diagram showing a configuration of a conventional comparison device. First, a configuration of a conventional comparison device will be described with reference to FIG. 3, reference numeral 81 denotes an input terminal which is a device input, 1 denotes a voltage source connected to the input terminal 81, 82 denotes an output terminal which is a device output, 9 denotes a resistor connected to the output terminal 82, 62, 63 , 65, 6
6, 68, 71 and 72 are transistors, 61 and 70 are resistors, 64, 67 and 69 are current sources, which are formed on one semiconductor, and 6 is a power supply voltage source. The transistors 66, 68 and 72 form a current mirror circuit.

Next, the operation of the above-mentioned conventional comparison device will be described with reference to FIG. 3, a reference voltage V obtained by flowing a current Ics of a current source 69 and a collector current Ic68 of a transistor 68 into a series circuit including a resistor 70 and a diode-connected transistor 71.
b63 is the terminal voltage V70 of the resistor 70 and the transistor 7
It is well known that if the base-emitter voltage Vbe71 is set so that the magnitude of the voltage change per one degree of temperature is the same and the polarities are reversed, the reference voltage has a small temperature dependency. I have.

A current source 69 having a characteristic such that an output current Ics often used in a semiconductor integrated circuit has a characteristic represented by [Equation 1] (for example, disclosed in Japanese Patent Application Laid-Open No. 60-191508). Vb6
3 is represented by [Equation 2].

[0005]

(Equation 1)

[0006]

(Equation 2)

The temperature change rate of Vbe71 is about -2 mV / d
When the magnitude of the resistance value of the resistor 70 is set so that the temperature change rate of V70 is about +2 mV / deg, the temperature dependence of the reference voltage Vb63, which is the sum thereof, is small. Become. Now, assuming that the collector current Ic68 of the transistor 68 is zero, if T is set to a normal temperature of 300 ° K, the reference voltage Vb63 becomes about 1.2
It becomes 5V.

The reference voltage Vb63 is applied to the transistor 6
The base of the transistor 63 which is one input of the differential amplifier composed of the differential amplifiers 2 and 63, and the base of the transistor 62 which is the other input is connected to an input terminal 81 which is a device input.
And the voltage V1 of the voltage source 1 connected to the input terminal 81, which is the device input, is compared with the reference voltage Vb63.

When V1> Vb63, the transistor 6
Since the emitter potentials of the transistors 2 and 63 are equal, the transistor 6
2, the base-emitter voltage Vbe62 is larger than the base-emitter voltage Vbe63 of the transistor 63, and most of the current of the current source 64 is the collector current of the transistor 62. When the collector current of the transistor 62 flows into the resistor 61, the base potential of the transistor 65 decreases and the transistor 65 is saturated. Therefore, the current I67 of the current source 67 flows as the collector current of the transistor 65, and the collector current of the transistor 66 becomes zero.

The transistors 66, 68, and 72 form a current mirror circuit. Since the collector current of the input transistor 66 is zero, the output transistor 6
8, the collector current Ic68 also becomes zero, and the current flowing into the series circuit including the resistor 70 and the diode-connected transistor 71 is only the current Ics of the current source 69.
If the reference voltage Vb63 at this time is Vb63L, Vb
63L is represented by [Equation 3].

[0011]

(Equation 3)

At this time, the collector current of the transistor 72 is also zero, the current flowing into the resistor 9 is also zero, and the potential of the output terminal 82 is low.

When V1 <Vb63, the transistor 62
Of the transistor 6
3 is smaller than the base-emitter voltage Vbe63, most of the current of the current source 64 is the collector current of the transistor 63, almost no current flows into the resistor 61, the base potential of the transistor 65 is high, and the transistor 65 is cut off. .

Therefore, the current I67 of the current source 67 flows as the collector current of the transistor 66, which is the input of the current mirror, and the collector current Ic68 of the transistor 68, which is the output of the current mirror, together with the current Ics of the current source 69, the resistor 70 and the diode Connected transistor 7
1 is a current flowing into the series circuit consisting of Assuming that the reference voltage Vb63 at this time is Vb63H, Vb63H is represented by [Equation 4].

[0015]

(Equation 4)

At this time, the collector current of the transistor 72 becomes a current flowing into the resistor 9, and the potential of the output terminal 82 increases.

That is, when V1> Vb63, the transistor 65 is saturated, and Vb63 becomes Vb63L. V
1 falls below Vb63L, the collector current of transistor 65 decreases, and the reference voltage changes from Vb63L to Vb63V.
Change to 63H to perform positive feedback operation. Therefore, the difference between V1 and Vb63 increases, the transistor 65 is cut off, and the potential of the output terminal 82 is increased.

On the other hand, when V1 <Vb63, the transistor 65 is cut off, and Vb63 becomes Vb63H. When V1 increases and exceeds Vb63H, transistor 6
5, the reference current changes from Vb63H to Vb63L, and a positive feedback operation is performed. Therefore, V
The difference between 1 and Vb63 expands in the opposite direction, and the transistor 6
5 saturates and lowers the potential of the output terminal 82. As described above, when the potential of the output terminal 82 becomes high, V1 ≦
When Vb63L is low, V1 ≧ V
It has a hysteresis characteristic of the voltage represented by the hysteresis Vhy [Equation 5] which shifts at b63H.

[0019]

(Equation 5)

As described above, in the conventional comparison device,
A comparison device having a built-in reference voltage Vb63L with small temperature dependence and having hysteresis with small temperature dependence is configured.

[0021]

However, in the configuration of the prior art as shown in FIG. 3, if the temperature dependence of the reference voltage Vb63L is set to be small, the reference voltage Vb6
3L becomes approximately 1.25 V, and a current source 6 for flowing current therethrough.
A power supply voltage Vcc equal to or larger than the following expression (6) obtained by adding the reference voltage Vb63L to the minimum collector-emitter voltage Vce (min) of the output transistor 9 or the transistor 68 is required.

[0022]

(Equation 6)

That is, assuming that the minimum collector-emitter voltage Vce (min) is about 0.2 V, the power supply voltage Vc
Since the minimum value of c is about 1.45 V, the power supply voltage Vcc
Has a first problem that it cannot be used at a voltage lower than about 1.45V.

If the temperature dependency of the reference voltage Vb63L is set to be small, Vb63L becomes about 1.25
Since it is fixed at V and it is difficult to set a lower voltage, it is necessary to reduce the magnitude of the second term of the above [Equation 3] and use it while allowing the temperature dependency to increase. There is a second problem that the reference voltage and the temperature characteristics cannot be controlled independently.

The present invention has been made to solve the first and second problems of the prior art, and has a power supply voltage of 1.4.
Operates at 5V or less, and incorporates a reference voltage with low temperature dependence at 1.25V or less (generated inside the circuit, same hereafter)
It is another object of the present invention to provide a comparison device having a hysteresis characteristic.

[0026]

A comparison device according to the present invention comprises a current mirror circuit, a first resistor voltage divider connected to an input of the current mirror circuit, and a voltage divider output of the first resistor voltage divider. A first current generator that supplies current to the current mirror circuit, a second current generator connected to the input of the current mirror circuit, a second resistor voltage divider connected to the output of the current mirror circuit, A third current generator configured to supply a current to the divided voltage output of the resistance voltage divider, a fourth current generator connected to an output of the current mirror circuit, and a first current generator and a third current generator. Is controlled so that its current value is proportional to the absolute temperature and inversely proportional to the current value setting resistor, and the temperature characteristics of the current value setting resistors of the first and third current generating portions are The resistances of the resistors constituting the first and second resistor dividers are And a variable current generating means for outputting a first value or a second value in accordance with the output of the comparing means. It is.

According to the present invention, the power supply voltage is reduced to 1.4.
A comparison device that operates at 5 V or less, has a built-in reference voltage at 1.25 V or less and has low temperature dependency, and has a hysteresis characteristic in the output voltage can be obtained.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention according to claim 1 of the present invention provides a comparing means having a built-in reference voltage, and a variable means for outputting a first value or a second value according to the output of the comparing means. Current comparing means, wherein the comparing means includes a current mirror circuit, a first resistor voltage divider connected to an input of the current mirror circuit, and a current divider output from the first resistor voltage divider. A first current generating unit for flowing current, a second current generating unit connected to an input of the current mirror circuit, a second resistor voltage dividing unit connected to an output of the current mirror circuit,
A first current generator configured to supply a current to a divided output of the second resistor voltage divider and a fourth current generator connected to an output of the current mirror circuit, wherein the first current The generator and the third current generator are configured such that the current value is controlled to a magnitude proportional to the absolute temperature and inversely proportional to the current value setting resistor, and the first current generator and the third current generator And the temperature characteristics of the current value setting resistor and the temperature characteristics of the resistors constituting the first and second resistor dividers are equalized.
The reference voltage is equivalent to a forward voltage that changes negatively with respect to the temperature obtained by flowing the current of the current generating section through the diode-connected transistor at the input of the current mirror circuit, and a positive voltage that corresponds to the temperature. Is obtained by multiplying the voltage obtained by adding the voltage generated by the current generating section and the voltage obtained by the resistance voltage dividing section to the voltage dividing ratio of the resistance voltage dividing section. For example, the temperature dependence of these two voltages is canceled out. With such a configuration, there is an effect that the temperature dependency is small and the voltage can be set to about 1.25 V or less.

According to a second aspect of the present invention, the current value of the variable current generating means is controlled to a magnitude inversely proportional to a current setting resistance of the variable current generating means, Temperature characteristics of the current value setting resistor of the current generating means, temperature characteristics of the current value setting resistors of the first current generating section and the third current generating section, and the first resistor voltage dividing section and the second resistor. The variable current generating means is configured to output a first value or a second value in accordance with an output of the comparing means, so that a temperature characteristic of a resistor constituting the voltage dividing unit is equalized. By adding the reference voltage set so that the temperature dependency is reduced, the output current of the variable current generating means, and the voltage having a small temperature dependency obtained by the resistance voltage dividing unit, the temperature dependency is reduced. Same as small reference voltage Small hysteresis characteristic temperature dependency has the effect that can be set.

According to a third aspect of the present invention, the current mirror circuit is constituted by a bipolar transistor. The current mirror circuit is efficient with a simple circuit and has a temperature dependency at 1.25 V or less. This has the effect that a comparison device incorporating a small reference voltage and having a hysteresis characteristic in the output voltage can be obtained.

(Embodiment) Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings, FIG. 1 and FIG. FIG. 1 is a circuit diagram showing a configuration of a comparison device according to an embodiment of the present invention. FIG. 2 is a diagram showing a circuit obtained by extracting a part of the comparison unit shown in FIG.
2A is a diagram showing the input side of the current mirror circuit of the analogous circuit of the comparison unit shown in FIG. 1, and FIG. 2B is a diagram showing the current source 2 of FIG.
2, (C) is a diagram showing an equivalent circuit of the current source 24 and the transistor 25 in FIG. 2 (B), and (D) is a diagram showing a current source 24 in FIG. 2 (B). FIG. 2E is a diagram showing an equivalent circuit of the transistor 25 and the resistors 22 and 23, and FIG. 2E is a diagram showing the current source 24 and the transistor 25 and the resistors 22 and 23 of FIG. FIG. 2F is a diagram showing an equivalent circuit of the reference voltage sources (Vref1, Vref2) of the comparison device shown in FIG.

First, with reference to FIG. 1, the configuration of a comparison device according to an embodiment of the present invention will be described. In FIG. 1, reference numeral 10 denotes a built-in reference voltage, and a comparator 20 and an amplifier 4
Reference numeral 50 is a variable current generating unit that outputs currents of a first value and a second value (to be described later) in response to an input. It comprises a comparing means 10 and a variable current generating means 50.

In the comparison section 20, 25 and 35 are bipolar transistors constituting a current mirror circuit (first current mirror circuit), and 21, 24, 31, and 34 are current transistors whose current values are proportional to the absolute temperature and which are built in. A low-voltage operation type current source that is inversely proportional to the set resistance (first, second, and
Third and fourth current generating units (hereinafter, also simply referred to as current sources), 22 and 23 are resistors constituting a resistive voltage dividing unit (first resistive voltage dividing unit), and 32 and 33 are resistive voltage dividing units ( The resistors constituting the second resistor voltage dividing unit), 2 and 3, are input terminals of the comparing unit 10, 36 is an output terminal of the comparing unit 20, and 1 is a voltage source.

In the amplifying section 40, 41 and 42 are bipolar transistors constituting a current mirror circuit (second current mirror circuit), 43 is bipolar transistors connected to the bipolar transistors 25 and 35 and the current mirror, and 44 is a bipolar transistor connected to the current mirror. Is a bipolar transistor connected to the input terminal, 46 is a bipolar transistor connected to the output terminal of the comparison means, 45 is a low-voltage operating current whose current value is proportional to the absolute temperature and inversely proportional to the built-in current value setting resistor. A source (fifth current generating unit, hereinafter simply referred to as a current source), 37 is an input terminal from the comparing unit 20, and 7 is an output terminal of the comparing unit 10.

In the comparison section 20, the voltage V1 input to the input terminal 2 and the reference voltage V3
, And a signal corresponding to the comparison result is obtained from the output terminal 36. In the amplifier 40, a signal corresponding to a change in the signal input to the input terminal 37 is output from the output terminal 7. It is configured as follows.

In the variable current generating means 50, 51 is a bipolar transistor receiving an input signal, 54, 56
Are bipolar transistors constituting a third current mirror, 52, 53, 57 bipolar transistors constituting a fourth current mirror, and 55 is a current whose output current value is proportional to a reference voltage having a small temperature dependency and which is incorporated therein. A low-voltage operation type current source (sixth current generation unit, hereinafter simply referred to as a current source) controlled to have a magnitude inversely proportional to the value setting resistance, 8 is an input terminal of the variable current generation means 50, and 4 and 5 are The output terminal of the variable current generating means 50, 6 is a power supply voltage source, 9
Is the output resistance.

The variable current generating means 50 switches the output current value at the output terminals 4 and 5 to a first value or a second value (described later) in response to a change in the signal input to the input terminal 8. It is configured as follows. The comparing means 10 and the variable current generating means 50 are formed on one semiconductor chip.
The above-mentioned bipolar transistor is simply referred to as a transistor hereinafter.

Next, referring to FIGS. 1 and 2, the operation of the comparison device according to one embodiment of the present invention will be described. First, the voltage V1 of the voltage source 1 connected to the input terminal 2 of the comparing means 10 is compared with the voltage V3 of the input terminal 3 of the comparing means 10 serving as a reference voltage. The potential of the input terminal 8 of the variable current generator 50 connected to the output terminal 7 is high, and the output current of the output terminals 4 and 5 of the variable current generator 50 is zero (first value).
The current flowing into the input terminal 3 connected to the output terminal 5 is also zero, and the reference voltage is Vref1. Further, the potential of the output terminal 4 to which the resistor 9 is connected is in a low state.

Then, when V1 becomes low and falls below Vref1, an output current flows to the output terminals 4 and 5, an inflow current flows to the input terminal 3, and the reference voltage starts shifting from Vref1 to Vref2. The potential of the output terminal 4 changes high. When V1 becomes sufficiently low, the input terminal 8
, The output current further flows through the output terminals 4 and 5 (second value), the inflow current further flows into the input terminal 3, and the reference voltage becomes Vref2. Also,
The potential of the output terminal 4 becomes high.

When V1 rises again and exceeds Vref2, the output currents of the output terminals 4 and 5 decrease, the inflow current to the input terminal 3 also decreases, and the reference voltage changes from Vref1 to Vref1.
The transition to ref2 is started, and the potential of the output terminal 4 changes to low. When V1 becomes sufficiently high, the potential of the input terminal 8 further increases, the output currents of the output terminals 4 and 5 further decrease, the inflow current to the input terminal 3 further decreases, and the reference voltage becomes Vref1. Further, the potential of the output terminal 4 becomes low again. Therefore, the reference voltage is set to Vref1 or Vref2 according to the voltage V1 of the voltage source 1.
To realize the hysteresis characteristic that is switched.

Next, each circuit means (comparing unit 20, amplifying unit 4)
0, the operation of each variable current generating means 50) will be described in detail. First, in the comparison unit 20, a current source 24 and a current source 24 are connected to the collector of an input-side diode-connected transistor 25 constituting a current mirror circuit.
A resistance voltage dividing section composed of resistors 22 and 23 is connected, and a current source 21 and an input terminal 3 of the comparing means 10 are connected to a divided voltage output of the resistance voltage dividing section. On the other hand, a current source 34, a resistive voltage dividing section composed of resistors 32 and 33, and an output terminal 36 of the comparing section 20 are connected to the collector of the output transistor 35 constituting the current mirror circuit. The current source 31 and the input terminal 2 of the comparing means 10 are connected to the divided voltage output of the resistance voltage dividing section.

In the following description, for the sake of simplicity, it is assumed that nothing is connected to the input terminals 2 and 3 and the output terminal 36, and that the transistor 43 of the amplifier 40 is not connected. Except that the transistor 25 is diode-connected, the left and right sides have the same configuration and the same constant. That is, the resistors 22 and 32, and the resistors 23 and 3
3, current source 21 and current source 31, current source 24 and current source 3
4. It is assumed that the transistors 25 and 35 are configured to correspond to each other.

First, the reference voltage incorporated in the comparison section 20 will be described. The resistors 22 and 23 on the left and the current source 2
1, 24 and a diode-connected transistor 25
And the input terminal 3. FIG. 2A is a diagram in which these parts are extracted from FIG. In FIG. 2A, since there are two signal sources, the current source 21 is considered to be open for analysis by using the superposition theory. FIG.
(B) shows that the current source 21 is open.

FIG. 2C shows a diode-connected transistor 25 and a current source 24 connected to a voltage source 251 and a resistor 25.
2 is represented by an equivalent circuit 250 constituted by the two elements. The voltage V251 of the voltage source 251 and the resistance value R25 of the resistor 252
2 is represented by [Equation 7] and [Equation 8], respectively.

[0045]

(Equation 7)

[0046]

(Equation 8)

FIG. 2D shows that the equivalent circuit 250 and the resistors 22 and 23 are connected to the voltage source 2 using the Otori-Thevenin theorem.
This is represented by an equivalent circuit 220 including a resistor 21 and a resistor 222. The voltage V221 of the voltage source 221 and the resistor 222
Is represented by [Equation 9] and [Equation 10], respectively.

[0048]

(Equation 9)

[0049]

(Equation 10)

Here, the current source 21 is considered. (E) of FIG. 2 is obtained by connecting the current source 21 to (D) of FIG. Assuming that the current source 21 is a current source as shown in [Equation 1], the current value Ics of the current source 21 flows into the voltage source 221 through the resistor 222, so that the voltage V3 of the input terminal 3 is set to [Equation 11] as the reference voltage Vref1. Will be represented by

[0051]

[Equation 11]

The first term in {} of [Equation 11] is the forward voltage of a diode-connected transistor of about 6
50 mV, and changes about −2 mV / deg with respect to the temperature.
If (R22 + R252) and the current value setting resistor Rcs are set so as to be 2 mV / deg, the voltage change with respect to temperature in the first and second terms can be canceled. this is,
It can be achieved by setting the second term in {} to 600 mV.

As a result, the temperature dependency of reference voltage Vref1 can be reduced. Further, the magnitude of the reference voltage can be easily set by the coefficient M. The reference voltage Vref1 is equal to the forward voltage Vf2 obtained by the diode-connected transistor 25 and the current source 24.
5, a voltage dividing resistor R22, 23 comprising resistors 22 and 23;
And a voltage obtained by multiplying the voltage obtained by the current source 21 by an absolute temperature T and a coefficient that does not depend on temperature, such as a resistance ratio, is added. The characteristics can be controlled, and the size can be easily set by the coefficient M.

Next, the similar operation of the comparing section 20 will be described. When the circuit constants obtained for setting the reference voltage Vref1 are assigned to the corresponding elements on the right side of the comparison unit 20 shown in FIG. 1, the left and right sides of the comparison unit 20 are provided by a current mirror circuit including transistors 25 and 35. A similar circuit in which the voltages and currents of the corresponding elements are the same is formed. The current I24 of the current source 24 is
, A collector current Ic25 of the transistor 25, and a base current (Ib25 + Ib35) of the transistor 25 and the transistor 35. It becomes as shown in [Equation 12].

[0055]

(Equation 12)

In [Equation 12], the base currents of the transistors 25 and 35 (Ib25 + Ib3
Considering 5), [Equation 12] is represented by [Equation 13].

[0057]

(Equation 13)

On the other hand, the current I34 of the current source 34 is divided into I32 flowing into the resistor 32 at the connection point B and the collector current Ic35 of the transistor 35.
It is represented by

[0059]

[Equation 14]

Since the transistors 25 and 35 constitute a current mirror circuit having a mirror ratio of 1: 1, the collector current Ic25 and the collector current Ic35 are equal, so that [Equation 14] is obtained from [Equation 14]. .

[0061]

(Equation 15)

By the way, since the current value I24 and the current value I34 are set to the same value, [Equation 13] and [Equation 1] are used.
5] and [Equation 16] is obtained.

[0063]

(Equation 16)

As can be seen from [Equation 16], the comparison unit 20
Since the currents of the left side circuit and the right side circuit are equal and the element constants are also equal, the respective voltages are also equal, and it can be seen that the two circuits perform similar operations.

Next, a state in which the voltage source 1 is connected to the input terminal 2 as shown in FIG. 1 will be considered. When the voltage V1 of the voltage source 1 is higher than the voltage V3 of the input terminal 3, the potential of the resistor 32 decreases, the current I32 flowing into the resistor 32 decreases, and a current (I34-I32) obtained by subtracting I32 from the current I34 of the current source 34. Increases and I34-I32 becomes Ic3
Therefore, the potential of the output terminal 36 increases because the current tends to flow to the output terminal 36 in the discharge direction.

On the other hand, when V1 is lower than V3, on the other hand, the potential of the resistor 32 increases, I32 increases, and I34-I
32 decreases, I34-I32 becomes smaller than Ic35, the current tends to flow to the output terminal 36 in the direction of absorbing current, and the potential of the output terminal 36 decreases. This operation is equivalent to the operation of an amplifier in which the input terminal 2 is the non-inverting input, the input terminal 3 is the inverting input, the reference voltage Vref1 is connected, and the output is the output terminal 36. The reference voltage Vref1 is expressed by the above [Equation 11], and as described above,
Temperature dependency is small and can be set to a value of 1.25 V or less.

Next, a state in which the variable current generating means 50 is connected to the input terminal 3 of the comparing means 10 will be considered. FIG. 2F shows an equivalent circuit 500 of the variable current generating means 50 composed of a current source 501 and a switch 502 connected to the input terminal 3 of FIG. When the switch 502 is off, that is, when the output current of the variable current generating means 50 is zero, the inflow current to the input terminal 3 becomes zero, which is equal to (E) in FIG. At this time, the voltage V3 of the input terminal 3 is equal to the reference voltage Vre built in the comparing means 10.
f1 and is represented by the above [Equation 11].

On the other hand, when the switch 502 is on, that is, when the output current of the variable current generating means 50 is flowing into the input terminal 3, if the output current value of the variable current generating means 50 is I55, the resistance 222 The inflow current is Ics +
I55, and the voltage V3 of the input terminal 3 becomes a reference voltage Vref2 which is a value obtained by adding a reference voltage Vref1 built in the comparing means 10 and a voltage drop generated by flowing I55 through the resistor 222. It is represented by

[0069]

[Equation 17]

As described above, the comparison unit 20 includes the reference voltage Vref1 having a small temperature dependency obtained by adding the forward voltage of the diode-connected transistor and the voltage obtained from the resistance voltage dividing unit and the current source. A reference voltage Vref2 obtained by adding the reference voltage Vref1 and a voltage drop generated by flowing the output current of the variable current generating means to the resistance voltage dividing unit.
Will also be built-in.

As described above, in the comparison section 20, when V1> V3, V3 becomes the reference voltage Vref1, the potential of the input terminal 8 of the variable current generating means 50 is high, and the transistor connected to the input terminal 8 Reference numeral 51 denotes an output terminal 4 of the variable current generating means 50 which is saturated and is an output of the device.
Is in a low state. Now, V1 decreases and Vre
When the voltage falls below f1, the potential of the input terminal 8 decreases, the collector current Ic51 of the transistor 51 decreases, the output current of the variable current generating means 50 increases, and the reference voltage becomes Vref1.
The positive feedback operation changes from Vref2 to Vref2.

On the other hand, when V1 and V3 are reversed and the difference between them is enlarged, the transistor 51 is cut off and the output current of the variable current generating means 50 becomes I55. Therefore, the transistor 54 forming the current mirror circuit,
The inflow current flowing into the resistor 9 through the output terminal 4 controlled via 56 and the transistors 52 and 53 becomes I55, and the potential of the output terminal 4 increases. That is, V1 <
At the time of V3, on the contrary, V3 becomes the reference voltage Vref2, the potential of the input terminal 8 is low, the transistor 51 is cut off, and the potential of the output terminal 4 is high.

When V1 rises again and exceeds Vref2, the potential of the input terminal 8 rises, the collector current Ic51 of the transistor 51 increases, the output current of the variable current generating means 50 decreases, and the reference voltage becomes Vref2. From Vref
A positive feedback operation changing to 1 is performed. That is, V1 and V3
When the difference increases in the opposite direction, the transistor 51 saturates, the output current of the variable current generating means 50 becomes zero, the current flowing into the resistor 9 connected to the output terminal 4 becomes zero, and the potential of the output terminal 4 becomes Lower.

As described above, in the state of V1 ≦ Vref1, the transition is made to increase the potential of the output terminal 4, and conversely, V1
In the state of ≧ Vref2, there is a hysteresis characteristic which shifts to lower the potential of the output terminal 4. The hysteresis voltage Vhy is represented by the following [Equation 18].

[0075]

(Equation 18)

Second, the operation of the amplifier 40 will be described. Amplifying unit 40 connected to output terminal 36 of comparing unit 20
When the potential of the input terminal 37 is high, the base potential of the transistor 44 connected to the input terminal 37 increases, and the collector current Ic44 of the transistor 44 increases. Accordingly, the collector current Ic44 and the collector current Ic of the transistor 42 connected to the collector of the transistor 44 are
The base current Ib46 of the transistor 46 connected to the collector of the transistor 44, which is the difference current from c42, decreases, and the collector current Ic46 of the transistor 46 also decreases.

Then, the collector current Ic46 becomes smaller than the output current I45 of the current source 45 connected to the collector of the transistor 46, and the current tends to flow to the output terminal 7 connected to the collector of the transistor 46 in the direction of discharging. The potential of the output terminal 7 increases.

On the other hand, when the potential of input terminal 37 is low, conversely, collector current Ic44 of transistor 44 decreases, base current Ib46 of transistor 46 increases, and collector current Ic46 of transistor 46 also increases. Then, when the collector current Ic46 becomes larger than the output current I45 of the current source 45, the current tends to flow into the output terminal 7 in the direction of sinking, and the potential of the output terminal 7 becomes low.

The circuit composed of the transistors 43, 41 and 42 is for eliminating the influence of the base currents of the transistors 25 and 35 of the comparison section 20. 44 is a circuit for setting a base current. The collector of the transistor 43 that forms a current mirror circuit with the transistors 25 and 35 of the comparison unit 20 is connected to the collector of the transistor 41 which is the input of the current mirror circuit formed by the transistors 41 and 42, and is the output of the current mirror circuit. The collector of transistor 42 is connected to the collector of transistor 44.

The mirror ratio of the current mirror circuit composed of the transistors 41 and 42 is set to 1: 3, and the collector current of the transistor 44 is set to flow three times the collector current of the transistor 43. At the connection point A of the comparison unit 20, the current I24 of the current source 24 is
2, the collector current Ic25 of the transistor 25, and the base current of each of the transistors 25, 35, and 43.

On the other hand, at the connection point B, the current I34 of the current source 34 is the current I32 flowing into the resistor 32, the collector current Ic35 of the transistor 35, and the
4 together with the base current Ib44. I24
And I34 are equal in circuit configuration, and
5, 35, and 43 constitute a current mirror circuit having a mirror ratio of 1: 1: 1 and include transistors Ic25 and Ic35 and transistor 4
3 have the same collector current Ic43.

If the transistors 25, 35, and 43 are composed of transistors having the same characteristics and each base current is Ib, the collector current Ic4 of the transistor 44 is obtained by the current mirror circuit composed of the transistors 41 and 42.
The current flowing through each part of the left and right circuits can be made equal by setting the size of Ib44 to be Ib × 3 by flowing the current 4 at three times the current Ic43.

As described above, by removing the influence of the base currents of the transistors 25 and 35 of the comparison unit 20, the difference between the terminal voltages of the input terminals 2 and 3 causes the variation in the current amplification factor hfe of the transistors. Worked independently.

As described above, the amplifying section 40 has the input terminal 37
When the potential of the output terminal 7 increases, the potential of the output terminal 7 increases. On the contrary, when the potential of the input terminal 37 decreases, the potential of the output terminal 7 decreases.
The influence of the base currents of the transistors 25 and 35 of the comparison section 20 is eliminated by the circuit composed of 42.

Third, the operation of the variable current generating means 50 will be described. When the potential of the input terminal 8 connected to the output terminal 7 of the comparing means 10 is high and the transistor 51 whose base is connected to the input terminal 8 of the variable current generating means 50 is saturated, the transistor 51 is connected to the collector of the transistor 51. The output current I55 of the current source 55
Flows as the collector current Ic51 of the
The input current I56 to the first current mirror circuit including the transistors 56 and 54 connected to the collector of the first current mirror circuit becomes zero, and the transistor 53 connected to the collector of the transistor 54 which is the output of the first current mirror circuit.
The input current I53 to the second current mirror circuit composed of 57 and 52 also becomes zero, and the output current of the output terminals 4 and 5 connected to the transistors 57 and 52, which is the output of the second current mirror circuit, becomes zero (the 1 value).

On the other hand, the input terminal 8 of the variable current generating means 50
Is low and the transistor 51 is cut off, the output current I55 of the current source 55 flows as the input current I56 of the first current mirror circuit, the input current I53 of the second current mirror circuit flows, and the output terminal 4 5 output currents. If the mirror ratio of the first current mirror circuit is 1: 1 and the second current mirror ratio is 1: 1: 1, the output currents of the output terminals 4 and 5 are represented by the following [Equation 19]. I55 (second value) as described above.

As described above, the variable current generating means 50 can switch the output current of the output terminals 4 and 5 to the first value or the second value according to the potential of the input terminal 8. Therefore, a variable current generating unit configured so that the current value as represented by [Equation 19] is controlled to be proportional to the reference voltage Vref55 having a small temperature dependency and to be controlled in inverse proportion to the current value setting resistor. When used as the current source 55, it is possible to realize a comparison device having a built-in reference voltage Vref1 having low temperature dependency and having a hysteresis characteristic having low temperature dependency.

[0088]

[Equation 19]

By substituting I55 of [Equation 19] for [Equation 17], Vref2 is expressed by [Equation 20].

[0090]

(Equation 20)

Vref1 and Vref55 in [Equation 20] are both reference voltages with small temperature dependence, and R2
When the temperature characteristics of the resistor 22 and the current value setting resistor R55 are made the same, the temperature characteristics of the resistor are canceled because (R222 / R55) is in the form of the ratio of the resistance, and the temperature dependence of Vref2 is reduced. Therefore, the hysteresis characteristic Vhy of the output voltage is expressed by [Equation 21], and the temperature dependence is reduced.

[0092]

(Equation 21)

As described above, according to the embodiment of the present invention, the reference voltage Vref1 expressed by [Equation 11] is added to the forward voltage Vf25 obtained by the diode-connected transistor 25 and the current source 24 by the resistance. Since the voltage is obtained by adding a voltage obtained by multiplying a voltage independent of a temperature such as an absolute temperature T or a resistance ratio to a voltage obtained by the voltage dividing resistors R22 and 23 formed by the current sources 21 and 22 and 23, By changing the distribution of these voltages, the temperature characteristics can be controlled, and the magnitude can be easily set by a coefficient M.

Further, the reference voltage Vref1 is set so as to have a small temperature dependency, and the current value of the current source 55 is proportional to the reference voltage having a small temperature dependency and inversely proportional to the current setting resistor. By using a current source configured to be controlled, it is possible to realize a comparison device having a reference voltage Vref1 having a small temperature dependence and a hysteresis characteristic having a small temperature dependence as represented by [Equation 21]. it can.

The terminal voltages of the current sources 24 and 34 are the forward voltages of the diodes. The voltage of the divided output of each resistor voltage divider is set to be equal to or less than the forward voltage of the diodes. , 31, 34, and 45 as a low-voltage operation type current source that is proportional to the absolute temperature and inversely proportional to the current value setting resistance (for example, as disclosed in JP-A-60-191508).
, The power supply voltage of this comparison device is about 0.9
Can be used down to V.

In addition, as the current source 55, a low-voltage operation type current source whose output current value is controlled to be proportional to the reference voltage having small temperature dependency and inversely proportional to the current value setting resistor (for example, U.S. Pat.
1 to realize a comparison device having a hysteresis characteristic with small temperature dependency, and can be used with the power supply voltage lowered to about 0.9V.

Further, in [Equation 11], R252 is R
22 is set sufficiently smaller than the reference voltage Vref1.
R22, R23, R32, R33, Rc
Since s is in the form of a ratio, it does not depend on the accuracy of the absolute value, and a semiconductor integrated circuit can be configured with high accuracy. In [Equation 20], the reference voltage V
Similarly, since the resistors R222 and R55 related to ref2 are in the form of a ratio, they do not depend on the accuracy of the absolute value, so that a semiconductor integrated circuit can be configured with high accuracy.

In this embodiment, the input terminal 2 of the comparing means 10 is used as the device input, the output terminal 5 of the variable current generating means is connected to the input terminal 3, and the input terminal 37 of the amplifying section 40 is connected.
When the potential of the output terminal 7 becomes high, the potential of the output terminal 7 becomes high, and when the potential of the input terminal 37 becomes low, the potential of the output terminal 7 becomes low.
When the potential of the input terminal 2 of 0 becomes higher, the potential of the output terminal 7 becomes higher, and conversely, when the potential of the input terminal 2 becomes lower, the potential of the output terminal 7 becomes lower. May be non-inverted.

Therefore, the input terminal 3 of the comparing means 10 is used as the device input, the output terminal 5 of the variable current generating means is connected to the input terminal 2, and when the potential of the input terminal 37 of the amplifying section 40 increases, the potential of the output terminal 7 increases. And the potential of the output terminal 7 increases when the potential of the input terminal 37 decreases, the same effect can be obtained. The reference voltage when the device input was the input terminal 2 was the voltage V3 of the input terminal 3, but the reference voltage in this case was not the voltage of the input terminal 2 but the output current value of the variable current generating means 50 was switched. The voltage of the input terminal 3 at this time becomes the reference voltage.

In the embodiment of the present invention, the variable current generating means 50 is configured so that the first value of the output current is 0 and the second value of the output current is I55. A first value such that the reference voltage when the first value is input to the input terminal 2 or the input terminal 3 of the comparison means 10 is lower than the reference voltage when the second value of the output current is input;
The second value may be used.

Further, in the embodiment of the present invention, in order to compensate for the influence of the base current of the transistors 25 and 35 at the connection point A, the circuit including the transistors 43, 41 and 42 If the current of the same magnitude as the base current of the transistor is withdrawn from the connection point B, but as a result the current of the same magnitude as the base current of the transistor withdrawn from the connection point A is withdrawn from the connection point B, It may be realized by other methods.

In this embodiment, the current sources 21 and 3
1 is set so that its current value is proportional to the absolute temperature T and inversely proportional to the current value setting resistor Rcs, and the current source 55 is proportional to the reference voltage Vref55 having a small temperature dependency and inversely proportional to the current value setting resistor R55. I am trying to do it. However, this can be realized by a current source having any characteristic. However, in this case, the influence on the temperature of the reference voltage or the fluctuation of the power supply voltage may have characteristics different from those of the present embodiment.

Further, in the present embodiment, the current mirror circuit is constituted by bipolar transistors, but this may be a current mirror circuit using any element. In this case, the temperature characteristics of the reference voltage differ depending on the element, and may be set so as to adapt to the temperature characteristics.

[0104]

The comparison device according to the present invention is constructed as described above. In particular, (1) the current mirror circuit is composed of bipolar transistors, and the temperature obtained from the diode-connected transistor at the input of the current mirror circuit is obtained. A forward voltage that makes a negative change with respect to the voltage and a voltage that makes a positive change with respect to the temperature obtained by the current source and the resistor voltage divider are added to the voltage added so as to cancel the change with respect to each other. By setting the value obtained by multiplying the voltage dividing ratio of the voltage dividing section as the reference voltage built in the comparing means, it is possible to provide a reference voltage of 1.25 V or less and having a small temperature dependency.

(2) When the current mirror circuit is a bipolar
A forward voltage that consists of transistors and has a negative change with respect to the temperature obtained from the diode-connected transistor at the input of the current mirror circuit, and a positive change with respect to the temperature obtained by the current source and the resistor voltage divider 1.25 V or less by changing the composition of each voltage by making the value obtained by multiplying the voltage obtained by adding the voltage to be divided by the voltage dividing ratio of the resistance voltage dividing section the reference voltage built in the comparing means. And a reference voltage capable of controlling the temperature characteristic can be provided.

(3) The current mirror circuit is a bipolar
A forward voltage that consists of transistors and has a negative change with respect to the temperature obtained from the diode-connected transistor at the input of the current mirror circuit, and a positive change with respect to the temperature obtained by the current source and the resistor voltage divider The value obtained by multiplying the voltage to be applied and the voltage applied so as to offset the change with respect to the temperature by the voltage dividing ratio of the resistance voltage dividing section is used as the reference voltage incorporated in the comparing means, and the output current value of the variable current generating means Is proportional to the reference voltage, which has a small temperature dependency, and is controlled to have a magnitude inversely proportional to the current value setting resistor.
It is possible to provide a reference voltage that is 1.25 V or less, has low temperature dependence, and has low temperature dependence of hysteresis characteristics.

(4) Set the reference voltage and the output terminal voltage to 0.
7V or less, and a low voltage operation type current source which is proportional to the absolute temperature and inversely proportional to the current value setting resistor is used as the current source of the comparison means, and the output current value is temperature dependent as the current source of the variable current generation means. If a low-voltage operation type current source controlled to have a magnitude proportional to the small reference voltage and inversely proportional to the current value setting resistor is used, the reference voltage having a small temperature dependency is built in, and the temperature dependency is small. It has hysteresis characteristics and can reduce the power supply voltage to about 0.9V.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration of a comparison device according to an embodiment of the present invention.

2A and 2B are diagrams illustrating a circuit extracted from the comparison unit illustrated in FIG. 1 for the purpose of describing a reference voltage; FIG. 2A illustrates an input side of a current mirror circuit of a similar circuit of the comparison unit illustrated in FIG. 1; (B) is a diagram showing a circuit in which the current source 21 shown in FIG. 2A is open. (C) A current source 24 and a transistor 25 shown in FIG.
(D) The current source 24 and the transistor 25 shown in FIG.
And FIG. 2E shows an equivalent circuit of a portion including the resistors 22 and 23. (E) The current source 24 and the transistor 25 shown in FIG.
FIG. 3F is a circuit diagram showing a circuit in which the current source 21 is connected to an equivalent circuit including a resistor and resistors 22 and 23. FIG.
1, an equivalent circuit of Vref2)

FIG. 3 is a circuit diagram showing a configuration of a conventional comparison device.

[Explanation of symbols]

1, 6 Voltage source 2, 3 Input terminal of comparator 4, 5 Output terminal of variable current generator 7 Output terminal of comparator 8 Input terminal of variable current generator 9, 22, 23, 32 Resistance 33, 61, 70 Resistors 21, 24, 31, 34, 45 Current sources 55, 64, 67, 69 Current sources 25, 35, 41, 42 Transistors 43, 44, 46, 51 Transistors 52, 53, 54, 56 Transistors 57, 62, 63 , 65 Transistors 66, 68, 71, 72 Transistors 10 Comparing means having a built-in reference voltage 20 Comparing section 36 Output terminal of comparing section 37 Input terminal of amplifying section 40 Amplifying section 50 Variable current generating means 60 Conventional comparing apparatus 81 Comparative apparatus Input terminal 82 Output terminal of comparator 220 Transistor 25, current source 24, resistor 22,
3 equivalent circuit 221 transistor 25, current source 24, resistor 22, 2
Equivalent voltage source 222 in the equivalent circuit of part 3 Transistor 25, current source 24, resistor 22, 2
3 Equivalent resistance in the equivalent circuit of the part 250 250 Transistor 25, Equivalent circuit of the part of the current source 24 251 Transistor 25, Equivalent voltage source in the equivalent circuit of the part of the current source 24 252 Equivalent of the part of the transistor 25 and the part of the current source 24 Equivalent resistance in circuit 500 Equivalent circuit of variable current generating means 501 Equivalent current source in equivalent circuit of variable current generating means 502 Equivalent switch in equivalent circuit of variable current generating means

Claims (3)

[Claims] 1. A comparison means comprising a reference voltage and variable current generation means for outputting a first value or a second value in accordance with an output of the comparison means, wherein the comparison means comprises a current mirror. A first resistor voltage divider connected to an input of the current mirror circuit; a first current generator for flowing a current to a voltage divider output of the first resistor voltage divider; and a current mirror circuit A second current generating unit connected to the input of the current mirror circuit, a second resistive voltage dividing unit connected to the output of the current mirror circuit, and a second current dividing unit for supplying a current to the divided voltage output of the second resistive voltage dividing unit. 3 current generator and a fourth current generator connected to the output of the current mirror circuit, wherein the first current generator and the third current generator have a current value proportional to the absolute temperature. To be controlled in inverse proportion to the current setting resistance. And the temperature characteristics of the current setting resistors of the first and third current generating units and the temperature characteristics of the resistors constituting the first and second resistor voltage dividing units. A comparison device characterized in that they are equal to each other. 2. The variable current generator according to claim 1, wherein a current value of said variable current generator is controlled to a magnitude inversely proportional to a current setting resistor of said variable current generator. Characteristics, temperature characteristics of the current value setting resistors of the first current generating unit and the third current generating unit, and temperature characteristics of the resistors constituting the first resistor voltage dividing unit and the second resistor voltage dividing unit 2. The comparing device according to claim 1, wherein the variable current generating means is configured to output a first value or a second value in accordance with an output of the comparing means. . 3. The current mirror circuit according to claim 1, wherein said current mirror circuit comprises a bipolar transistor.
Or the comparison device according to 2.