JPH1098342A - Gain adjustment circuit and frequency conversion circuit - Google Patents

Abstract

(57) [Summary] [Problem] To have a temperature compensation function in a gain adjustment circuit,
An object of the present invention is to realize gain linearity in a wide temperature range in a temperature compensation function. SOLUTION: A variable voltage attenuator 11 which sets a loss amount according to a control voltage, attenuates a gain of a high frequency input signal and outputs the attenuated gain, and a gain at the time of temperature change with respect to a predetermined fixed attenuation amount at a constant temperature. The bias voltage setting circuit 12 adds a compensation amount to the fixed attenuation amount and outputs the control voltage corresponding to the added attenuation amount to the variable voltage attenuator via a resistor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gain adjustment circuit and a frequency conversion circuit for a high-frequency circuit used in the field of communications such as mobile communications.

[0002]

2. Description of the Related Art Some conventional gain adjustment circuits have or do not have a temperature compensation function. inside that,
In the case of a device having no temperature compensation function, temperature compensation was performed in individual amplifiers attached to the device, so that several thermistors as temperature compensation elements had to be used. Further, even a gain adjustment circuit having a temperature compensation function has only a compensation gain linearity of ± 1.5 to 2.0 dB or less in a wide temperature range from a low temperature to a high temperature.

[0003]

Due to the above factors, the gain adjustment circuit having no temperature compensation function has a problem that the circuit scale other than the gain adjustment circuit becomes large. The gain adjustment circuit has a problem that it is difficult to guarantee the linearity of the compensation gain of ± 1.5 to 2.0 dB or more.

[0004] In view of the above problems, an object of the present invention is to provide a gain adjustment circuit and a frequency conversion circuit having a temperature compensation function capable of guaranteeing gain linearity over a wide temperature range.

[0005]

In order to achieve the above object, a gain adjusting circuit according to the present invention sets a loss amount according to a control voltage, attenuates the gain of a high frequency input signal, and outputs the variable variable attenuation. And a gain compensation amount at the time of a temperature change with respect to a predetermined fixed attenuation amount at a constant temperature is added to the fixed attenuation amount, and a control voltage corresponding to the added attenuation amount is output to a voltage variable attenuator via a resistor. And a bias voltage setting circuit. According to the present invention, the gain adjustment circuit has a temperature compensation function, and the temperature compensation function can realize gain linearity over a wide temperature range.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention according to claim 1 of the present invention provides a voltage variable attenuator for setting a loss amount according to a control voltage, attenuating the gain of a high-frequency input signal, and outputting the attenuated gain, A bias voltage for adding a gain compensation amount at the time of temperature change to a predetermined fixed attenuation amount to the fixed attenuation amount, and outputting the control voltage corresponding to the added attenuation amount to the voltage variable attenuator via a resistor. This is a gain adjustment circuit composed of a setting circuit, and has the function of simultaneously operating two functions of a gain adjustment function and a temperature compensation function.

According to a second aspect of the present invention, the variable voltage attenuator is configured such that two resistors are connected in series in a signal transmission line direction, and a diode is connected between a connection point of the two resistors and ground. 2. The gain adjustment circuit according to claim 1, wherein
It has the same effect as the described invention.

According to a third aspect of the present invention, a bias voltage setting circuit includes a variable resistor and a fixed resistor connected in series between a power supply and a ground, a thermistor connected in parallel to the fixed resistor, and a control voltage output from the connection point. The gain adjustment circuit according to the first aspect has the same operation as the first or second aspect of the invention.

The invention according to claim 4 is the gain adjustment circuit according to claim 3, wherein the bias voltage setting circuit is configured so that n (n ≧ 2) thermistors are connected in parallel to the fixed resistor. When realizing thermistors having the same fixed resistance value, the specific resistance value of each thermistor is increased to increase the rate of resistance change, thereby maintaining the linearity of the compensation gain in a wide temperature compensation range.

According to a fifth aspect of the present invention, there is provided a low-frequency signal circuit for inputting and amplifying a low-frequency signal, and a high-frequency signal output by converting the output of the low-frequency signal circuit by a local signal output from a local oscillator. And a circuit for inputting a high-frequency signal, removing unnecessary signal components, amplifying the signal, and outputting a frequency-converted signal, wherein the gain adjustment circuit according to claim 1 is disposed in the low-frequency signal circuit. This is a frequency conversion circuit having a wide frequency range by arranging a gain adjustment circuit in a low-frequency circuit system between a low-frequency signal of frequency f0 and a high-frequency signal of frequency f1 having a frequency relationship of f0 <f1 before and after the multiplication circuit. It has the effect of ensuring a variable attenuation range.

According to a sixth aspect of the present invention, there is provided a high-frequency signal circuit for inputting a high-frequency signal and removing and amplifying an unnecessary signal component, and a low-frequency signal output from the high-frequency signal circuit is frequency-converted by a local signal output from a local oscillator. A frequency conversion circuit comprising: a multiplication circuit that outputs a frequency signal; and a circuit that amplifies a low-frequency signal and outputs a frequency-converted signal, wherein the low-frequency signal circuit includes the gain adjustment circuit according to claim 1. The gain adjustment circuit is arranged in a circuit system having a low frequency between a low-frequency signal of frequency f0 and a high-frequency signal of frequency f1 having a frequency relationship of f0 <f1 before and after the multiplication circuit.
It has the same effect as the described invention.

According to a seventh aspect of the present invention, there is provided a first variable voltage attenuator for setting a loss amount according to a first control voltage, attenuating the gain of a high-frequency input signal, and outputting the attenuated gain, The gain compensation amount at the time of temperature change is added to the first fixed attenuation amount to the first fixed attenuation amount, and a first control voltage corresponding to the added attenuation amount is applied to the first fixed attenuation amount via the first resistor. A first bias voltage setting circuit for outputting to the voltage variable attenuator of
A variable voltage attenuator for attenuating the gain of the output signal of the first variable voltage attenuator and outputting the same, and a second predetermined fixed attenuation under a constant temperature. , A gain compensation amount smaller than the gain compensation amount in the first variable voltage attenuator at the time of temperature change is added to the second fixed attenuation amount, and a second control voltage corresponding to the added attenuation amount is added. A second bias voltage setting circuit for outputting to the second variable voltage attenuator via the second resistor, and a first bias voltage setting circuit for maintaining the linearity of the compensation characteristic over a wide temperature range.
For the maximum compensable amount of voltage variable attenuator of
By setting the insufficient amount of compensation in the gain adjustment circuit, the same operation as the first to sixth aspects of the invention can be obtained.

The invention according to claim 8 is the first or second invention.
The variable gain attenuator according to claim 7, wherein a diode is connected between a connection point and the ground in series with two resistors in the signal transmission path direction, similar to the invention according to claim 7. Has the action of

According to a ninth aspect of the present invention, in the first bias voltage setting circuit, a variable resistor and a fixed resistor are connected in series between a power supply and a ground, and a thermistor is connected in parallel with the fixed resistor. A gain adjustment circuit according to claim 7, wherein the control voltage is output from a connection point with the fixed resistor, and has the same operation as the invention according to claim 7.

According to a tenth aspect of the present invention, the second bias voltage setting circuit includes a variable resistor, a thermistor, and a fixed resistor connected in series between a power supply and a ground, and controls a combined voltage drop of the fixed resistor and the thermistor with a control voltage. This is a gain adjustment circuit configured to output as a signal, and has the same operation as the invention according to claim 7.

According to an eleventh aspect of the present invention, there is provided a low-frequency signal circuit for inputting and amplifying a low-frequency signal, and converting the output of the low-frequency signal circuit by a local signal output from a local oscillator to convert a high-frequency signal. 8. A multiplication circuit for outputting, and a circuit for receiving the high-frequency signal, removing unnecessary signal components, amplifying and outputting a frequency-converted signal, wherein the gain adjustment circuit according to claim 7 is arranged in the low-frequency signal circuit. This is a frequency conversion circuit configured to perform the same operation as that of the fifth aspect of the present invention.

According to a twelfth aspect of the present invention, there is provided a high-frequency signal circuit for inputting a high-frequency signal and removing and amplifying an unnecessary signal component;
A multiplication circuit for converting the output of the high-frequency signal circuit with a local signal output from a local oscillator to output a low-frequency signal, and a circuit for amplifying the low-frequency signal and outputting a frequency-converted signal; A frequency conversion circuit having a gain adjustment circuit according to claim 7 in a frequency signal circuit, and has the same operation as the invention according to claim 6.

FIG. 1 shows an embodiment of the present invention.
This will be described with reference to FIG. (Embodiment 1) FIG. 1 shows a gain adjustment circuit according to Embodiment 1 of the present invention. In FIG. 1, a voltage variable attenuator 11 that sets a loss amount according to a control voltage, attenuates the gain of a high-frequency input signal 101 and outputs the attenuated gain, A bias voltage setting circuit 12 adds a gain compensation amount to the fixed attenuation amount and outputs a control voltage corresponding to the added attenuation amount to the voltage variable attenuator 11 via a resistor 102. Here, the variable voltage attenuator 11 includes two resistors 104, 1 connected in series in the direction of the high-frequency signal transmission line as shown in FIG.
It is possible to use a T-type gain attenuator having a configuration in which the diode 106 is connected between the connection point 05 and the ground, and the cathode of the diode 106 is connected to the ground and the anode is connected to the connection point. The cathode of the diode 106 is connected to the signal input side, the anode is connected to the signal output side, and a fixed resistor is connected between the control voltage input unit and the anode of the diode 106 and between the ground and the cathode of the diode. Although it is possible to use a π-type gain attenuator having the configuration as the variable voltage attenuator 11, a T-type gain attenuator can obtain a linear characteristic with a large attenuation with respect to the control voltage. Also,
In the bias voltage setting circuit 12, as shown in FIG. 3, a variable resistor 108 and a fixed resistor 107 are connected in series between a power supply and a ground, and a thermistor 109 is fixed between a connection point of the variable resistor 108 and the fixed resistor 107 and the ground. It is possible to use a resistor having a configuration connected in parallel to the resistor 107. Although a voltage follower can be used as the bias voltage setting circuit 12, the size can be reduced by the circuit configuration using the variable resistor and the fixed resistor shown in FIG.

Next, FIG. 9 shows the measurement results of the temperature characteristics of the resistance value of the diode in the gain adjustment circuit and the case where 25 ° C. measured using the gain adjustment circuit having the characteristics shown in FIG. FIG. 10 shows the gain deviation when the temperature changes. FIG.
As is clear from FIG. 5, the slope of the gain deviation with respect to the temperature change increases as the zero load resistance value Rs of the diode decreases. However, the temperature relationship between the thermistor and the resistor is as follows: R = R0 exp [B (1 / T-1 / T0)] (1) where R0 is the resistance value at the temperature T0 [° K], and R Is the temperature T
The resistance value [° K], B, is a thermistor constant [° K], and the thermistor constant B indicates the temperature dependence of the thermistor.

The temperature coefficient α of the resistor has the following relationship: α = −B / T 2 (2), and the temperature change rate is determined by B and T.

FIG. 11 shows an example of the relationship between the diode forward voltage and the gain of the gain adjustment circuit, and FIG. 12 shows the relationship between the temperature and the compensation gain. In FIG. 12, the forward voltage VF and the forward current IF of the diode are determined for each temperature and compensation gain. Here, IF has a relationship represented by equation (3).

IF = IS [exp (qVF / (kT)) − 1] (3) where IS is the reverse saturation current, and q / (kT) ≒ 39.
(I / V) (T = 300 ° K).

Accordingly, the control voltage output from the bias voltage setting circuit shown in FIG. 3 is obtained by calculating the compensation gain and the forward voltage of the diode required at each temperature by the equations (1), (2) and (3). ) Is set so as to satisfy, it is possible to realize highly accurate temperature compensation.

(Embodiment 2) FIG. 4 shows a bias voltage setting circuit used in a gain adjustment circuit according to Embodiment 2 of the present invention. 4, in the bias voltage setting circuit shown in FIG. 3 as an example of the bias voltage setting circuit according to the first embodiment, n (n ≧ 2) thermistors 110-1, 110-2,. ............ 110-
n are connected in parallel.

9 and 10 shown in the first embodiment.
In addition, the zero load resistance value of the thermistor 109 shown in FIG.
The characteristics in the case of 10 kΩ, 4.3 kΩ, and 3.3 kΩ are represented by A, B, and C, respectively. In FIG. 9, the load resistance value is 3.3.
In the characteristic C, which is the case of kΩ, the gain deviation does not change linearly at a high temperature and becomes saturated, so that there arises a problem that accurate temperature compensation cannot be realized. This is because the thermistor constant B decreases as the specific resistance decreases, and the rate of change with respect to temperature decreases. On the other hand, the constant of n thermistors is smaller than that of a single thermistor under the condition satisfying the relations of the equations (1), (2) and (3) as in the present embodiment. By using the specific resistance value, characteristics as shown by D in FIG. 9 or FIG. 10 can be realized, and the temperature compensation range can be improved. Here, n thermistors 110-1,
, 110-n are not limited to those having the same characteristics, and may have different characteristics.

(Embodiment 3) FIG. 5 shows a frequency conversion circuit according to Embodiment 3 of the present invention. In FIG.
Low frequency signal circuit 13 for inputting and amplifying low frequency signal 112
A multiplication circuit 114 that converts the low-frequency signal circuit output 113 with a local oscillation signal 118 output from a local oscillation oscillator 115 and outputs a high-frequency signal 116;
A high-frequency signal circuit 14 receives the signal 16, removes unnecessary signal components, amplifies the signal, and outputs a signal 117 whose frequency has been converted. Here, by arranging the gain adjustment circuit of the first or second embodiment in the low-frequency signal circuit 13, it is possible to realize a wider variable gain range than when the gain adjustment circuit is arranged in the high-frequency signal circuit 14.

(Embodiment 4) FIG. 6 shows a frequency conversion circuit according to Embodiment 4 of the present invention. In FIG.
A high-frequency signal circuit 15 that receives a high-frequency signal 119 and removes and amplifies unnecessary signal components, and a high-frequency signal circuit output 120 is frequency-converted by a local signal 123 output from a local oscillator 122 to output a low-frequency signal 124. Multiplication circuit 1
21 and a low-frequency signal circuit 16 that amplifies the low-frequency signal 124 and outputs a frequency-converted signal 125. Here, by disposing the gain adjustment circuit of the first embodiment or the second embodiment in the low-frequency signal circuit 16,
As in the third embodiment, it is possible to realize a wider variable gain range than when the antenna is arranged in the high-frequency signal circuit 15.

(Embodiment 5) FIG. 7 shows a gain adjustment circuit according to Embodiment 5 of the present invention. In FIG. 7, a first variable voltage attenuator 17 that sets a loss amount according to a first control voltage, attenuates the gain of a high-frequency input signal 128, and outputs the attenuated gain, and a predetermined first fixed attenuator at a constant temperature. The gain compensation amount at the time of temperature change is added to the first fixed attenuation amount with respect to the attenuation amount, and the first control voltage corresponding to the added attenuation amount is applied to the first voltage variable attenuation via the first resistor 126. A first bias voltage setting circuit 18 for outputting to the amplifier 17 and a loss amount corresponding to the second control voltage to attenuate the gain of the output signal 129 of the first variable voltage attenuator 17 to output the signal 130. A second variable voltage attenuator 19 that performs a predetermined second
The gain compensation amount smaller than the gain compensation amount in the first bias voltage setting circuit 18 when the temperature changes with respect to the fixed attenuation amount is added to the second fixed attenuation amount. The second bias voltage setting circuit 20 outputs the second control voltage to the second variable attenuator 19 via the second resistor 127. Here, as the first and second voltage variable attenuators 17 and 19, a diode 106 is connected between the connection point of two resistors 104 and 105 connected in series in the direction of the high-frequency signal transmission path as shown in FIG. It is possible to use a T-type gain attenuator having a configuration in which the cathode of 106 is connected to the ground and the anode is connected to the connection point. As the first bias voltage setting circuit 18, two resistors 104 and 105 are connected in series in the direction of the high-frequency signal transmission line as shown in FIG. 2, and a diode 106 is connected between the connection point and the ground.
06 has a configuration in which the cathode is connected to the ground and the anode is connected to the connection point, or n (n ≧ 2) thermistors 110 are connected in parallel to the fixed resistor 107 as shown in FIG. It is possible to use what was constituted so that it might do. Further, as the second bias voltage setting circuit 20, a variable resistor 131, a thermistor 132 and a fixed resistor 13 are connected between a power supply and a ground as shown in FIG.
3 are connected in series and a control voltage is output from a connection point between the variable resistor 131 and the thermistor 132. The thermistor 13
The same effect can be obtained even if the connection relationship between 2 and the fixed resistor 133 is reversed. In the embodiment, it is possible to obtain an effect exceeding the effect obtained in each embodiment by simultaneously obtaining the functions obtained from the first embodiment and the second embodiment.

[0029]

As described above, according to the present invention, both the gain adjustment function and the temperature compensation function are provided, and the linear characteristic of the thermistor is compensated to minimize the gain deviation in a wide temperature range. An advantageous effect of realizing the temperature compensation characteristic can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram of a gain adjustment circuit according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing an example of a variable voltage attenuator used in the gain adjustment circuit.

FIG. 3 is a circuit diagram showing an example of a bias voltage setting circuit used in the gain adjustment circuit.

FIG. 4 is a circuit diagram showing an example of a bias voltage setting circuit used in a gain adjustment circuit according to a second embodiment of the present invention.

FIG. 5 is a block diagram of a frequency conversion circuit according to a third embodiment of the present invention.

FIG. 6 is a block diagram of a frequency conversion circuit according to a fourth embodiment of the present invention.

FIG. 7 is a block diagram of a gain adjustment circuit according to a fifth embodiment of the present invention.

FIG. 8 is a circuit diagram showing an example of a bias voltage setting circuit used in the gain adjustment circuit.

FIG. 9 is a temperature characteristic comparison diagram between the thermistor of the gain adjustment circuit according to the second embodiment of the present invention and a thermistor used in a conventional gain adjustment circuit.

FIG. 10 is a temperature characteristic comparison diagram between the gain adjustment circuit according to the second embodiment of the present invention and a conventional gain adjustment circuit.

FIG. 11 is a characteristic diagram of the gain adjustment circuit according to the first, second, and fifth embodiments of the present invention.

FIG. 12 is a characteristic diagram of the gain adjustment circuit according to the first, second, and fifth embodiments of the present invention.

[Explanation of symbols]

 Reference Signs List 11 voltage variable attenuator 12 bias voltage setting circuit 13 low frequency signal circuit 14 high frequency signal circuit 15 high frequency signal circuit 16 low frequency signal circuit 17 first voltage variable attenuator 18 first bias voltage setting circuit 19 second voltage variable Attenuator 20 second bias voltage setting circuit 101 high-frequency input signal 102 fixed resistance 103 high-frequency signal 104 fixed resistance 105 fixed resistance 106 diode 107 fixed resistance 108 variable resistance 109 thermistor 110 thermistor 112 low-frequency signal 113 low-frequency signal 114 multiplication circuit 115 Local oscillator 116 High frequency signal 117 High frequency signal 118 Local signal 119 High frequency signal 120 High frequency signal 121 Multiplying circuit 122 Local oscillator 123 Local signal 124 Low frequency signal 125 Low frequency signal 126 Fixed resistor 127 Fixed resistor 128 high-frequency signal 129 frequency signal 130 frequency signal 131 the variable resistor 132 thermistor 133 fixed resistor

Claims (12)

[Claims] 1. A variable voltage attenuator for setting a loss amount according to a control voltage, attenuating the gain of a high-frequency input signal and outputting the attenuated gain, and a gain at a temperature change with respect to a predetermined fixed attenuation amount at a constant temperature. A gain adjustment circuit comprising: a bias voltage setting circuit that adds a compensation amount to the fixed attenuation amount and outputs the control voltage corresponding to the added attenuation amount to the variable voltage attenuator via a resistor. 2. The gain adjustment circuit according to claim 1, wherein the variable voltage attenuator has a configuration in which a diode is connected between a connection point of two resistors connected in series in a direction of a high-frequency signal transmission line and a ground. . 3. The bias voltage setting circuit according to claim 1, wherein a variable resistor and a fixed resistor are connected in series between a power supply and a ground.
2. The gain adjustment circuit according to claim 1, further comprising a thermistor connected in parallel with the fixed resistor between a connection point between the variable resistor and the fixed resistor and a ground, and outputting a control voltage from the connection point. . 4. The gain adjustment circuit according to claim 3, wherein the bias voltage setting circuit has n (n ≧ 2) thermistors connected in parallel to the fixed resistor. 5. A low-frequency signal circuit for inputting and amplifying a low-frequency signal, a multiplying circuit for converting the output of the low-frequency signal circuit by a local signal output from a local oscillator and outputting a high-frequency signal, 2. A frequency conversion circuit that receives the high-frequency signal, removes unnecessary signal components, amplifies the signal, and outputs a frequency-converted signal, wherein the low-frequency signal circuit includes the gain adjustment circuit according to claim 1. 6. A high-frequency signal circuit for inputting a high-frequency signal and removing and amplifying an unnecessary signal component, and a low-frequency signal output by converting the output of the high-frequency signal circuit by a local signal output from a local oscillator. A frequency conversion circuit, comprising: a multiplication circuit; and a circuit for amplifying the low-frequency signal and outputting a frequency-converted signal, wherein the low-frequency signal circuit includes the gain adjustment circuit according to claim 1. 7. A first variable voltage attenuator for setting a loss amount according to a first control voltage, attenuating the gain of a high-frequency input signal and outputting the attenuated gain, and a predetermined first fixed attenuation at a constant temperature. A gain compensation amount at the time of a temperature change is added to the first fixed attenuation amount, and the first control voltage corresponding to the added attenuation amount is supplied to the first voltage variable via a first resistor. A first bias voltage setting circuit that outputs to the attenuator, and a second voltage variable that sets a loss amount according to the second control voltage and attenuates the gain of the output signal of the first bias voltage setting circuit and outputs the resulting signal. An attenuator, and a second fixed attenuation that reduces a gain compensation amount smaller than the gain compensation amount in the first bias voltage setting circuit when a temperature changes with respect to a predetermined second fixed attenuation amount at a constant temperature. The second control voltage corresponding to the added attenuation amount is added to a second resistor. A second bias voltage setting circuit for outputting to the second variable voltage attenuator via the second variable voltage attenuator. 8. The variable voltage attenuator according to claim 7, wherein the first and second variable voltage attenuators have a configuration in which a diode is connected between a connection point of two resistors connected in series in a signal transmission line direction and ground. Gain adjustment circuit. 9. The first bias voltage setting circuit has a variable resistor and a fixed resistor connected in series between a power supply and a ground, and a fixed resistor connected in parallel between a connection point of the variable resistor and the fixed resistor and the ground. 8. The gain adjustment circuit according to claim 7, further comprising a thermistor, and outputting a control voltage from said connection point. 10. A second bias voltage setting circuit having a variable resistor, a thermistor, and a fixed resistor connected in series between a power supply and a ground, and using a combined voltage drop of the fixed resistor and the thermistor as a control voltage. 8. The gain adjusting circuit according to claim 7, wherein the signal is output. 11. A low-frequency signal circuit for inputting and amplifying a low-frequency signal, a multiplying circuit for converting the output of the low-frequency signal circuit with a local signal output from a local oscillator and outputting a high-frequency signal, 8. A frequency conversion circuit that receives the high-frequency signal, removes unnecessary signal components, amplifies the signal, and outputs a frequency-converted signal, wherein the low-frequency signal circuit includes the gain adjustment circuit according to claim 7. 12. A high-frequency signal circuit which receives a high-frequency signal and removes and amplifies an unnecessary signal component, and outputs a low-frequency signal by converting the output of the high-frequency signal circuit by a local signal output from a local oscillator. A frequency conversion circuit comprising: a multiplication circuit; and a circuit that amplifies the low-frequency signal and outputs a frequency-converted signal, wherein the low-frequency signal circuit includes the gain adjustment circuit according to claim 7.