JPH0697765A - Phase temperature compensating circuit - Google Patents

Abstract

(57) [Abstract] [Purpose] An output phase temperature compensation circuit that compensates for fluctuations in the output phase of an electronic circuit due to temperature and keeps it constant, and compensates for nonlinear output phase temperature characteristics in which the relationship between temperature and output phase can be approximated by a broken line The purpose is to get out. A phase control circuit 6 in which a phase difference between an input signal and an output signal changes in proportion to a control voltage, and a temperature sense voltage VT having a linear relationship with temperature are input, and a specific limit temperature T0 or higher or At the following temperatures, it increases or decreases monotonically with respect to the temperature, and at other temperatures, the control voltage VC is constant.
The partial temperature compensating circuit 4 in combination with the control voltage generating circuit 5 for generating NT is constituted by one or a plurality of series connections. The control voltage generating circuit uses a transistor differential pair in which the reference voltage is input to one base and the temperature sense voltage is input to the other base, and the control voltage is output from the collector of either one of the bases. And the gain of the transistor differential pair are adjusted so that the limit temperature T
This is a configuration in which 0 and the rate of change of the control voltage with respect to temperature are set arbitrarily.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an output phase temperature compensating circuit for compensating fluctuations in the output phase of an electronic circuit due to temperature and keeping it constant.

In electronic circuits and the like for processing digital signals,
The phase of the output signal with respect to the input signal is required to be constant even when the operating temperature changes, and for this purpose, the output phase temperature compensation circuit is used.

[0003]

2. Description of the Related Art When an input signal is processed by an electronic circuit composed of semiconductor elements such as transistors to obtain an output signal, the phase difference of the output signal with respect to the input signal (hereinafter abbreviated as output phase) usually changes with temperature. Correspondingly changes monotonically. Therefore, for temperature compensation of the output phase, a phase control circuit in which the output phase changes linearly with the control voltage (that is, the control voltage and the phase shift characteristic have a linear relationship) is used as the output phase temperature compensation circuit. By directly controlling the phase control circuit with the temperature sensing voltage from the temperature sensing circuit, which is added after the electronic circuit and utilizes the fact that the forward voltage drop of the diode changes linearly with temperature, An opposite phase change is applied to the output signal to keep the phase of the output signal constant regardless of the temperature.

However, elements such as SAW filters (surface wave filters) do not have a linear change in phase characteristic due to temperature, and a circuit including such an element does not have a linear temperature characteristic of output phase. The temperature compensation method cannot sufficiently compensate the output phase.

For example, the clock extraction circuit shown in FIG.
Used in an optical receiver module in digital optical communication, it is a circuit for extracting a clock signal from a received data signal. This circuit includes a clock component extraction unit 1, a phase temperature compensation circuit 2, and a limiter amplifier 3. The clock component extraction unit 1 differentiates an NRZ input data signal to generate a pulse train at each level change point,
The SAW filter 12 extracts the sine wave of the clock frequency by filtering the pulse train. Phase temperature compensation circuit 2
Is a phase control circuit 21 that linearly changes the output phase with respect to a sine wave signal input by the control voltage VCNT, and a temperature that outputs a temperature sense voltage VT that rises in proportion to the temperature rise as the temperature rises, as a control voltage. It consists of a sense circuit 22. The limiter amplifier 3 limiter-amplifies the phase temperature compensated sine wave signal from the phase control circuit 21, pulse-shapes it, and outputs an output clock signal.

FIG. 9 is a diagram showing an output phase temperature characteristic of the clock component extracting section. As shown in FIG. 9, the phase temperature characteristic of the differentiating circuit 11 including only the semiconductor element is that the phase is delayed by the slope of −K2 ′ with respect to the temperature rise (one-dot chain line), and the SAW filter 12 which is the electromechanical conversion element Regarding the phase temperature characteristic, the phase is delayed (dotted line) regardless of whether the temperature rises or falls from the room temperature T0.

Therefore, the phase-temperature characteristics of the clock component extraction unit 1 in which these two circuits are connected in series are those in which the respective temperature-phase characteristics are combined, and the gradient K1 at low temperature → T0 and the gradient K2 at T0 → high temperature. The output phase temperature characteristics approximated by the broken line are shown.

On the other hand, the conventional phase temperature compensation circuit 2
Since the linear compensation with a constant slope with respect to temperature is performed, only the temperature-temperature characteristic of the differentiating circuit having a linear temperature-output phase characteristic can be canceled out.Therefore, the output phase of the clock extraction circuit with such a circuit configuration is at room temperature. On the other hand, both the low temperature and the high temperature are delayed, and the phase of the extracted clock varies according to the phase temperature characteristic of the SAW filter.

[0009]

As described above, a circuit having a non-linear phase temperature characteristic cannot be sufficiently compensated by a conventional temperature compensating circuit, so that a clock extracting circuit using a SAW filter or the like outputs an output depending on temperature. The phase change is large,
There is a problem that the error rate of the data identification reproduction is deteriorated when the received data is identified by the extracted clock because the margin is reduced due to the phase variation due to the temperature.

The present invention was created in view of the above problems, and an object of the present invention is to provide a phase temperature compensating circuit capable of temperature compensating an electronic circuit having a non-linear output phase temperature characteristic.

[0011]

FIG. 1 is a principle block diagram of a phase temperature compensating circuit of the present invention, and FIG. 4 is a detailed diagram of a control voltage generating circuit.

In order to solve the above problems, the phase temperature compensating circuit of the present invention is, as shown in FIG. 1, a compensated electronic circuit 1 having an arbitrary output phase temperature characteristic in which the relationship between temperature and output phase can be approximated by a broken line. An output phase temperature compensation circuit for compensating an output phase, the phase control circuit 6 having a phase difference between an input signal and an output signal that changes in proportion to a control voltage, and a temperature sense voltage VT having a linear relationship with temperature. Is input, and monotonically increases or decreases with respect to the temperature above or below a specific limit temperature T0, and has a constant control voltage V at other temperatures.
The partial temperature compensating circuit 4 in combination with the control voltage generating circuit 5 for generating CNT is composed of one or a plurality of series connections, and the control voltage generating circuit of the partial temperature compensating circuit is as shown in FIG. , The emitters are commonly connected, the reference voltage is input to one base, the temperature sense voltage is input to the other base, and the control voltage is output from one of the collectors, and Dynamic
The current source 52 supplies a constant current to the common emitter of 51, and the reference voltage VREF and the gain of the transistor differential pair 51 are adjusted to arbitrarily set the limit temperature T0 and the rate of change of the control voltage with respect to the temperature. This is the configuration to be set.

[0013]

[Function] In the phase compensation for a sine wave, the arithmetic sum of the phase temperature characteristics of a plurality of partial temperature compensation circuits becomes the entire phase characteristic. Therefore, connect a plurality of partial temperature compensation circuits with different characteristics in series. As a result, temperature compensation of an output signal having a phase temperature characteristic approximated by a polygonal line can be realized with high accuracy.

To this end, each of the plurality of partial temperature compensating circuits sets the limit temperature and the temperature-control voltage gradient so as to compensate for one broken line portion of the phase temperature characteristic of the compensated electronic circuit.

The limit temperature and the temperature-phase shift characteristic gradient can be set in each partial temperature compensation circuit as follows. Assuming that the input temperature sense voltage has a proportional relationship that increases linearly with increasing temperature, the difference between the reference voltage applied to the base of the transistor differential pair of the control voltage generation circuit and the temperature sense voltage at the limit temperature. The reference voltage is set so that the dynamic input cuts off one transistor of the differential pair. As a result, a control voltage that is constant with respect to the temperature on the high temperature side or the low temperature side of the limit temperature and has a predetermined gradient on the low temperature side or the high temperature side can be obtained.

Further, when the control voltage is taken out from the transistor to which the temperature sense voltage VT0 is applied to the base,
Since the current shunted to the transistor increases due to the temperature rise, a control voltage having a negative slope with respect to the temperature is obtained, and when the control voltage is taken out from the transistor to which the reference voltage VREFF is applied to the base, the temperature rises. Since the current in the transistor decreases, a control voltage with a positive slope with respect to temperature is obtained. That is, the positive / negative of the gradient of the control voltage with respect to the temperature can be set depending on which side of the transistor of the differential pair the control voltage is taken out from. Then, the absolute value of the gradient of VCNT can be arbitrarily adjusted by setting the voltage gain of the differential pair to an appropriate value.

As described above, the limit temperature and the temperature-control voltage gradient of each control voltage generation circuit can be set in accordance with each part of the polygonal line of the phase temperature characteristic of the compensated circuit. By connecting the combined partial temperature compensation circuits in series, the compensated circuit can be compensated with high accuracy.

[0018]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 2 is a configuration diagram of an embodiment of the present invention, FIG. 3 is a diagram showing an example of a phase control circuit, FIG. 4 is a detailed diagram of a control voltage generation circuit, FIG. 5 is an operation explanatory diagram of FIG. 4, and FIG. FIG. 7 is a classification diagram of circuit types of circuits, and FIG. 7 is a diagram of an example of compensation of a complicated phase temperature characteristic. Note that the same reference numeral represents the same object throughout the drawings.

FIG. 2 shows an embodiment in which the output phase temperature compensating circuit of the present invention is applied to the clock extracting circuit having the output phase temperature characteristic described above with reference to FIGS. In FIG. 2, the phase temperature compensating circuit of the present invention includes a low temperature compensating circuit (4a) and a high temperature compensating circuit (4b) which are inserted in series between the clock component extracting section 1 and the limiter amplifier 3. It is composed of two partial temperature compensation circuits and a temperature sensing circuit 7 which supplies a temperature sense voltage VT proportional to the temperature to the partial temperature compensation circuits.

As shown in FIG. 9, the phase of the sine wave of the extracted clock frequency output by the clock component extraction unit 1 has an arbitrary temperature T0 (limit temperature) within the operating temperature range (T1 to T2).
It is assumed that the gradient of the phase-temperature characteristic changes.

Therefore, in this embodiment, the temperature compensation of the output phase is performed by the two partial temperature compensation circuits which respectively compensate the high temperature side and the low temperature side with the limit temperature T0 as the boundary. That is, when T1 → T0, the temperature gradient is K1, and when T0 → T2, the gradient is 0.
With the partial temperature compensation circuit 4a having the phase characteristic of
The phase temperature characteristic of K1 is constant from T1 to T0, and
Partial temperature compensation circuit 4b having a phase characteristic of gradient K from 0 to T2
Thus, the phase temperature characteristic of the gradient -K2 on the high temperature side is shared and compensated.

The temperature sensing circuit 7 is constructed by connecting a diode 71, a potentiometer 72, and a constant current source 73 in series, and connecting the diode side to GRND and the constant current source side to a-power source. The voltage from the terminal is used as the sense voltage VT. This voltage becomes a temperature sense voltage VT that changes with a positive slope, that is, +2 mv / ° C, with respect to a temperature rise due to a temperature change (−2 mv / ° C) in the forward characteristic of the diode. The potentiometer is provided for adjusting the absolute level of the sense voltage to set the operating point of the differential amplifier described later.

The partial temperature compensating circuits 4a and 4b are supplied with control voltages VCNT1 and VCNT2 from the control voltage generating circuits 5a and 5b and the control voltage generating circuits 5a and 5b, respectively, and output phases are linear with respect to the control voltage. And a phase control circuit 6 that changes.

First, an example of the phase control circuit will be described with reference to FIG. The phase control circuit is a circuit to which a sine wave signal is input and in which the output phase of the output signal with respect to the input is advanced or delayed in proportion to the increase / decrease amount of the control voltage VCNT. The phase control circuit is composed of three pairs of transistor differential pairs 61, 62, 63, a 90 ° phase shift circuit 64, and a constant current source 65, and the first differential pair 61 supplies a constant current from the constant current source 65. Is shunted according to the control voltage VCNT. Then, the 0-phase input signal and the 90-degree phase-shifted input signal from the 90-degree phase shift circuit 54 are input to the two pairs of differential pairs 62 and 63 that use the two divided currents as common emitter currents, respectively. It inputs the signals, amplifies each signal, and obtains the sum of the outputs. When the shunting ratio of the collector current of the first differential pair 61 is changed by the control voltage VCNT, the gains of the two differential pairs 62 and 63 are changed in the opposite directions, so that the 0 phase signal and the 90 ° phase signal are changed. The mixing ratio changes, and the output phase can be changed in the range of 0 to 90 °.

In this embodiment, when the control voltage VCNT rises, the output phase advances at a predetermined rate. Next, the details of the control voltage generation circuit will be described with reference to FIG.

The control voltage generation circuits 5a and 5b are supplied with a temperature sense voltage VT which is linear with respect to the temperature from the temperature sense circuit, and exhibit a polygonal line characteristic at a predetermined limit temperature, and one of the polygonal lines is horizontal and the other is desired. Control voltage VC with a temperature gradient of
NT1 and VCNT2 are generated respectively,
The control voltage generating circuit 5 of FIG. 4 is commonly used for both the low temperature side and the high temperature side, and the setting value of the limit temperature and the setting of the temperature gradient are made different.

The control voltage generating circuit 5 shown in FIG. 4 is composed of a differential amplifier including a transistor differential pair 51 and a constant current source 52. The transistor differential pair 51 has load resistors RL1 and RL2 at the collectors thereof respectively, a reference voltage VREF and a temperature sense voltage VT are input to the respective bases thereof, and a pair of transistors TR1 and T1 having emitters commonly connected thereto.
It consists of R2. The constant current source 52 is a transistor differential pair 51
A constant current I ₀ is supplied to the common emitter of.

Generally, when the reference voltage and the input voltage are appropriately set, the output voltage of each transistor of the differential pair is 1 / 2I ₀ to both transistors when the input voltage VT is equal to the reference voltage VREF as shown in FIG. Since the same current flows in the input voltage, it linearly increases / decreases with respect to the input voltage around the operating point in a certain input range, and otherwise, the total current I ₀ from the constant current source increases.
Power supply voltage V
It is a constant value of CC or VCC-RL × I ₀ .

Therefore, in the linear operation range, the collector current of the transistor TR2 to which the sense voltage is input to the base increases as the input increases (that is, the temperature increases).
The voltage drop due to the load resistor RL2 increases and the output voltage decreases. That is, the control voltage VCNT1 having a negative slope with respect to the temperature change is obtained. Further, since the collector current of the transistor TR1 to which the reference voltage is input to the base decreases as the input voltage increases, the collector output voltage by the load resistor RL1 increases. That is, the control voltage VCNT2 having a positive slope with respect to the temperature rise is obtained.

Then, the reference voltage VREF is set to the limited temperature T0.
If it is set higher than the temperature sense voltage VT0 by 1/2 of the input dynamic range (range in which the differential pair operates linearly), the input voltage VT is within the linear range on the higher temperature side than the limited temperature T0, so that the output voltage changes with temperature. On the other hand, the output voltage (control voltage) becomes constant because the difference between the input voltage and the reference voltage becomes large on the temperature lower side than the limited temperature and exceeds the linear operation range of the differential pair, since the output voltage (control voltage) becomes constant.

When the reference voltage VREF is set smaller than the limited temperature sense voltage VT0 by 1/2 of the input dynamic range, the temperature range lower than the limited temperature T0 becomes the linear operation range of the differential pair, and the control voltage has a linear gradient with respect to temperature. It has a constant value on the high temperature side.

As described above, the positive / negative of the gradient of the control voltage with respect to the temperature depends on which output of the differential pair transistor is used, and the temperature range in which the control voltage is constant has a limit temperature T.
It can be selected to be 0 or more or less than 0 depending on whether the reference voltage VREF is set to a higher temperature side or a lower temperature side than the sense voltage VT0 at the limit temperature. Therefore, the relationship between temperature and control voltage is divided into four cases. This combination is shown in FIG. 6 in circuit formats (A) to (D). In the circuit shown in the figure, an emitter feedback resistor is inserted on the emitter side of the differential pair transistor, and this is varied to set the temperature-control voltage gradient to a value that can cancel the phase-temperature characteristic of the compensated circuit. To do.

Now, the temperature sense voltage VT output from the temperature sense circuit is T1 which is the lower limit temperature of the target temperature range.
It is assumed that the temperature sensing circuit is set so that VT1 is obtained at (for example, −40 ° C.) and VT2 is obtained at the upper limit temperature T2 (for example, 85 ° C.). At this time, the clock component extraction unit having the phase temperature characteristic shown in FIG. A phase temperature compensation circuit that performs temperature compensation of the output signal over the entire temperature range will be described.

For this purpose, two partial compensating circuits are connected in series so that the amount of phase lead is equal to the limit temperature T0 (for example, 20 °).
In C, the temperature sense voltage at this time is VT0).
On the higher temperature side, the temperature may increase with a constant gradient as the temperature rises.

Therefore, as the control voltage generating circuit 5a of the partial compensating circuit 4a on the low temperature side for compensating the phase delay which increases with the temperature drop on the temperature lower side than the limit temperature T0, the limit temperature T
A circuit type (A) in which the output voltage is constant on the higher temperature side than 0 and the output increases with the temperature drop on the lower temperature side is used.

Further, as the control voltage generating circuit 5b of the high temperature side partial compensating circuit 4b for compensating for the phase delay which increases with the temperature increase on the higher temperature side than the limit temperature, the output is constant on the lower temperature side than the limit temperature T0, and the high temperature side is obtained. On the side, a circuit type (C) whose output increases with temperature rise is used.

By inputting the control voltages VCNT1 and VCNT2 from the respective control voltage generating circuits to the phase control circuit 6a which shares the low temperature side and the phase control circuit 6b which shares the high temperature side, two phase control is performed. Since the circuit performs temperature compensation by dividing the signal having the output phase temperature characteristic shown in FIG. 9 from the clock extraction unit into the low temperature side and the high temperature side, the sine wave corresponding to the clock signal having the constant phase characteristic over the target temperature range. Is obtained. By passing this through a limiter amplifier 3, a clock signal in which the phase fluctuation due to temperature is compensated can be obtained.

Next, a temperature compensation circuit in the case where the compensated electronic circuit has a phase temperature characteristic approximated by a polygonal line having two or more inflection points will be described with reference to FIG. Now, the temperature-phase characteristic of the output signal of the compensated electronic circuit 1'is shown in FIG.
As shown in, the limit temperatures T1 and T
At 2, T3, the gradient showing the relationship between temperature and phase is k1 → k
It can be approximated by a polygonal line changing from 2 → k3 → k4. In this case, four partial temperature compensation circuits 4-1 to 4-4
, And the first partial temperature compensation circuit 4-1 has a phase shift amount / temperature gradient K1 = −k1 over the entire temperature range,
The second partial temperature compensating circuit 4-2 is constant up to T1 and has a gradient K2 =-(k1-K2) on the higher temperature side than T1, and the third partial compensating circuit 4-3 is constant up to T2 and is higher than T2. Gradient K on high temperature side
3 = − (k3−k1−k2), the fourth partial compensation circuit 4-4 is constant up to T3 and has a gradient K4 = − (k4-k1) on the higher temperature side than T3.
-K2-k3) so that each of the control voltage generation circuits 5-1 to 5-4 has a limit temperature and a gradient of the control voltages VCNT1 to 4 to compensate the phase temperature over the entire operating temperature range. Is possible.

[0039]

As described above, according to the phase temperature compensating circuit of the present invention, in the electronic circuit including the element whose temperature gradient of the output phase changes within the operating temperature range, the temperature gradient of the output phase is canceled. This makes it possible to obtain a signal whose output phase is stable with respect to temperature. Particularly, in a high-speed optical module or the like, the output phase of the reference clock can be compensated with high accuracy, so that optical digital communication with stable transmission characteristics can be realized.

[Brief description of drawings]

FIG. 1 is a principle configuration diagram of a phase temperature characteristic compensation circuit of the present invention.

FIG. 2 is a block diagram of an embodiment of the present invention.

FIG. 3 is a diagram showing an example of a phase control circuit.

FIG. 4 is a detailed diagram of a control voltage generation circuit.

5 is an explanatory diagram of the operation of FIG.

FIG. 6 is a classification diagram of the circuit form of the control voltage generation circuit.

FIG. 7 is a diagram showing an example of compensating a complicated phase temperature characteristic.

FIG. 8 is a diagram of a clock extraction circuit using a conventional output phase temperature characteristic compensation circuit.

FIG. 9: Output phase temperature characteristic of clock component extraction unit

[Explanation of symbols]

1 ... Clock component extraction unit (compensated electronic circuit), 3 ... Limiter amplifier, 4, 4a, 4b, 4-1 to 4-4 ... Partial temperature compensation circuit,
5,5a, 5b ... Control voltage generation circuit, 6 ... Phase control circuit, 7 ...
Temperature sensing circuit

Claims (2)

[Claims] 1. A compensated electronic circuit (1) having an arbitrary output phase temperature characteristic in which the relationship between temperature and output phase can be approximated by a broken line.
An output phase temperature compensation circuit that compensates the output phase of the phase control circuit (6) in which the phase difference between the input signal and the output signal changes in proportion to the control voltage, and the temperature that has a linear relationship with the temperature. A control voltage generation circuit (5a, 5b) to which the sense voltage VT is input and which monotonically increases or decreases with respect to a temperature above or below a specific limit temperature T0 and generates a constant control voltage VCNT at other temperatures. A phase temperature compensation circuit characterized by comprising one or a plurality of partial temperature compensation circuits (4a, 4b) connected in series. 2. The control voltage generation circuit (5) of the partial temperature compensation circuit (4a, 4b) has emitters connected in common, a reference voltage is input to one base, and a temperature sense voltage is input to the other base. A transistor differential pair (51) configured to output a control voltage from one of the collectors, and the differential pair (51)
Current source (52) that supplies a constant current to the common emitter of, and by adjusting the reference voltage VREF and the gain of the transistor differential pair (51), the limit temperature T0 and the rate of change of the control voltage with respect to the temperature 2. The phase temperature compensating circuit according to claim 1, wherein is set arbitrarily.