JPS6218923B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control voltage generation circuit that outputs a control voltage with desired temperature characteristics.

Electronic circuits such as amplifiers and oscillators have characteristics such as gain and oscillation frequency that change due to changes in ambient temperature. Therefore, temperature compensation means can be added to prevent the characteristics from changing due to changes in ambient temperature. It is common practice to avoid this. Such a temperature compensation means may be configured with a thermistor, for example, and change a control voltage such as a bias voltage in response to temperature changes, but since the temperature characteristics of electronic circuits are not linear, Compensation was difficult.

In addition, when performing complete temperature compensation, the characteristics of the electronic circuit must be measured at various ambient temperatures, and control voltages such as bias voltages must be set so that the characteristics at the measurement temperature point are constant. For example, if you set the control voltage using room temperature as the reference temperature, and make adjustments to set the control voltage so that the characteristics at the reference temperature and the characteristics at other measured temperature points are equal, the previously set The control voltage at the reference temperature will change. That is, since it is not possible to independently set the control voltage at each adjustment temperature point, there is a drawback that the adjustment becomes complicated.

The present invention improves the above-mentioned conventional drawbacks by independently setting control voltages such as bias voltages at each adjustment temperature point, and making it possible to generate control voltages with desired temperature characteristics. The purpose is to Examples will be described in detail below.

FIG. 1 is a circuit diagram of an embodiment of the present invention,
R ₁ to _{R 8} are resistors, S is a negative temperature sensitive resistor or thermistor, P is a positive temperature sensitive resistor or positor, D ₁ ,
D ₂ is a diode, DFA ₁ and DFA ₂ are differential amplifiers,
RV ₁ to _{RV 3} are variable resistors, OPA is an operational amplifier,
OUT is a control voltage output terminal, and +V and -V are power supply voltages. A constant voltage divided by resistors R ₇ and R ₈ is applied to the positive input terminal of the operational amplifier OPA, and the voltage is adjusted by variable resistors RV ₁ to _{RV 3} via resistors R ₃ to _{R 5} to the negative input terminal. The added voltage is added to form an adder circuit.

Also, the outputs of differential amplifiers DFA ₁ and DFA ₂ are variable resistors.
The voltage applied to RV ₁ and RV ₃ and adjusted by variable resistors RV ₁ and RV ₃ is added to the voltage adjusted by variable resistor RV ₂ . For example, if room temperature is the reference temperature, and the resistance value of the thermistor S and the resistance R ₁ at the reference temperature are equal, and the resistance value of the POSISTOR P and the resistance R ₂ are equal, then points a and b have zero potential. , the outputs of the differential amplifiers DFA ₁ and DFA ₂ become zero. Therefore, a control voltage proportional to the voltage adjusted by variable resistor RV ₂ is output. That is, at the reference temperature, the control voltage can be set by the variable resistor _RV2 .

At a high temperature higher than the reference temperature, the resistance value of the thermistor S decreases and the potential at point a becomes negative to a certain extent, so the output of the differential amplifier DFA ₁ becomes a
It corresponds to the potential at the point. Therefore variable resistance
By adjusting RV ₁ , the output voltage of differential amplifier DFA ₁ is divided and added to the voltage adjusted by variable resistor RV ₂ . In other words, the control voltage at high temperatures can be set by the variable resistor _RV1 . Note that the resistance value of the posistor P increases and the potential at point b becomes positive to a certain extent, but this is blocked by the diode _D2 and the output of the differential amplifier _DFA2 remains zero.

Also, at a low temperature lower than the reference temperature, the resistance value of the thermistor S increases and the potential at point a becomes positive to a certain extent, but this is blocked by the diode _D1 and the output of the differential amplifier _DFA1 becomes zero. Since the resistance value of the POSISTOR P becomes small, the potential at point b becomes a certain negative magnitude, and the output voltage of the differential amplifier DFA ₂ becomes a magnitude corresponding to the potential at point b. Therefore, the voltage divided by variable resistor RV ₃ is applied to variable resistor RV ₂
Since it is added to the voltage regulated by , the control voltage can be set by the variable resistor RV ₃ at low temperatures.

FIG. 2 is an explanatory diagram of the setting range of the control voltage,
If the reference temperature is tb, by setting the control voltage to V _G1 at the reference temperature tb, the low temperature ta and high temperature can be changed.
In the temperature range tc, the control voltage setting range is obtained as shown by the solid line, and when the control voltage at the reference temperature tb is set to V _G2 , the control voltage setting range is obtained as shown by the dotted line. The control voltage at each adjustment temperature point can be set independently.

FIG. 3 is a circuit diagram of another embodiment of the present invention,
This corresponds to the configuration in which the POSISTOR P in Fig. 1 is replaced with a resistor R ₁₂ , and the resistor R ₂ is replaced with a thermistor S ₂ .
S ₁ and S ₂ may have the same resistance temperature characteristics. In this embodiment as well, since the potentials at points a and b change depending on the temperature, the control voltage at the reference temperature is set by the variable resistor RV ₂ , and then the control voltage at the high temperature is set by the variable resistor RV2. The control voltage at low temperatures can be set by means of RV ₁ and by variable resistor RV ₃ respectively.

It is also possible to connect a POSISTOR in place of the thermistors S ₁ and S _2. In that case, the control voltage at high temperatures is controlled by variable resistor RV ₃ , and the control voltage at low temperatures is controlled by variable resistor RV _1. Each can be set. In addition, the variable resistor RV ₂ that sets the control voltage at the reference temperature is a fixed voltage divider circuit, and the positive input terminal of the operational amplifier OPA is connected to a variable voltage divider circuit with a variable resistor to set the control voltage at the reference temperature. It is also possible to configure a configuration in which .
If the connection polarities of the diodes D ₁ and D ₂ are reversed, the relationship between the adjusted temperature points is reversed so that the setting at a high temperature becomes the setting at a low temperature. It is also possible to omit the diodes D ₁ and D ₂ depending on the resistance-temperature characteristics of the thermistor and posistor.

FIG. 4 is a circuit diagram of still another embodiment of the present invention, and while each of the embodiments described above has three adjustment temperature points: a reference temperature, a low temperature, and a high temperature, this embodiment has a reference temperature and three adjustment temperature points. It has five adjustment temperature points: first and second low temperatures and first and second high temperatures. In the figure, S ₁₁ and S ₁₂ are thermistors, P ₁₁ and P ₁₂ are posistors, R ₁₃ to _{R 24} are resistors, DFA ₁₁ to DFA ₁₄ are differential amplifiers, RV ₁₁ to _{RV 15} are variable resistors, and OPA ₁ is operational amplifier, OUT is control voltage output terminal, +V, -V
is the power supply voltage. The thermistors S ₁₁ and S ₁₂ have different resistance-temperature characteristics, or if they have the same resistance-temperature characteristics, the values of the combined resistors R ₁₃ and R ₁₄ are different. Similarly, for POSISTORs P ₁₁ and P ₁₂ , the resistance temperature characteristics are different or the resistances are combined.
Let the values of R ₁₅ and R ₁₆ be different. Therefore a~d
The potentials at the points are different at each adjustment temperature point, and for example, the temperature-dependent changes in the differential output voltages of the differential amplifiers DFA ₁₁ to _{DFA 14} are selected as shown in Va to Vd in FIG.

If the temperature t ₃ in FIG. 5 is the reference temperature, the control voltage at the reference temperature can be set by the variable resistor RV ₁₃ , and at the first high temperature t ₄ higher than the reference temperature t ₃ . The control voltage can be set by variable resistor RV ₁₂ and, at a second higher temperature t ₅ , by variable resistor RV ₁₁ respectively. Also, at the first low temperature _t2 lower than the reference temperature _t3 , the variable resistance
The control voltage can be set by means of RV ₁₄ or, at a lower second temperature t ₁ , by means of variable resistor RV ₁₅ .

FIG. 6 is an explanatory diagram of the control voltage setting range,
For the control voltage at the reference temperature _t3 , each temperature
Since the positive or negative voltages at t ₁ , t ₂ , t ₄ , and t ₅ are added, for example, at the first high temperature t ₄ , a control voltage higher than the control voltage at the reference temperature t ₃ is applied. It is also possible to output a control voltage that is smaller than the control voltage at the reference temperature t ₃ at the second high temperature t ₅ .

FIG. 7 is a circuit diagram of still another embodiment of the present invention, in which each posistor P ₂₁ has different resistance-temperature characteristics.
~ _P23 and thermistors _S21 ~ _S23 are connected in series to form a temperature sensing circuit, where _D21 ~ _D23 are diodes, _DFA21 ~ _DFA23 are differential amplifiers, and _R25 ~ _R33
is a resistor, RV ₂₁ to _{RV 23} are variable resistors, OPA ₂ is an operational amplifier, OUT is a control voltage output terminal, and +V and -V are power supply voltages. The characteristics of each temperature sensing circuit are, for example,
As shown by curves A, B, and C in the figure, the temperatures at which the combined resistance value becomes minimum are different. DFA ₂₁ at this time ~
The input voltage of the differential amplifier of DFA ₂₃ is shown in Fig. 9A',
B′, C′ and at temperature t ₁ , the differential amplifier
At DFA ₂₁ and t ₂ , the output of the differential amplifier DFA ₂₂ and at t ₃ the output of the differential amplifier DFA ₂₃ becomes maximum, respectively, and at temperatures t ₁ , t ₂ , and t ₃ , the output of the variable resistor RV ₂₁ ,
RV ₂₂ and RV ₂₃ allow each control voltage to be set independently.

As explained above, the present invention inputs a voltage divided by a resistor and a temperature-sensitive resistor such as a thermistor or a posistor, and outputs a differential output voltage to the variable resistor RV ₁ ,
Differential amplifier DFA 1 , DFA _{2 ,} DFA ₁₁ to be added to RV ₃ , RV ₁₁ , RV ₁₂ , RV ₁₄ , RV ₁₅ , RV ₂₁ to _{RV 23}
DFA ₁₄ , DFA ₂₁ to DFA ₂₃ , and an operational amplifier that synthesizes the differential output voltage adjusted by a variable resistor.
It is equipped with OPA, OPA ₁ and OPA ₂ , and has the advantage that the control voltage at each adjustment temperature point can be set independently. Therefore, the control voltage for desired temperature characteristics can be easily set.

Note that it is also possible to connect an amplifier for converting the output impedance or for expanding the range of change of the control voltage to the output terminal OUT, and it is also possible to adopt a configuration in which the control voltage is output via a photocoupler or the like. That is, it is possible to provide a control voltage output circuit corresponding to the configuration of the circuit to which the control voltage is applied.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an embodiment of the present invention, FIG. 2 is an explanatory diagram of a control voltage setting range, FIGS. 3, 4, and 7 are circuit diagrams of different embodiments of the present invention, Figure 5 is a relationship curve between the differential output voltage and temperature of the differential amplifier in Figure 4, Figure 6 is an explanatory diagram of the setting range of the control voltage in Figure 4, and Figure 8 is the thermistor in Figure 7. FIG. 2 is a diagram showing the temperature characteristic curve of the combined resistance value of a thermosensing circuit connected in series with a POSISTOR. FIG. 9 is a temperature characteristic curve diagram of the input voltage of the differential amplifier in FIG. 7. DFA ₁ , DFA ₂ , DFA ₁₁ ~ DFA ₁₄ , DFA ₂₁ ~
DFA ₂₃ is a differential amplifier, RV ₁ ~ RV ₃ , RV ₁₁ ~ _{RV 15} ,
RV ₂₁ to _{RV 23} are variable resistors, OPA, OPA ₁ , OPA ₂ are operational amplifiers, D ₁ , D ₂ , D ₂₁ to _{D 23} are diodes,
S, S ₁ , S ₁₁ , S ₁₂ , S ₂₁ to _{S 23} are thermistors, P,
P ₁₁ , P ₁₂ , P ₂₁ to _{P 23} are posistors, and OUT is an output terminal.

Claims (1)

[Claims] 1. A plurality of differential amplifiers that input a voltage divided by a resistor and a temperature-sensitive resistor and apply a differential output voltage to a variable resistor, and an arithmetic circuit that synthesizes the voltage adjusted by the variable resistor to obtain a control voltage. A control voltage generation circuit comprising: