JPS5829533B2 - Ondo Hoshiyou Cairo - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a constant current type temperature compensation circuit that prevents output voltage from fluctuating due to temperature changes.

FIG. 1 shows an example of a conventional temperature compensation circuit using a diode, where the temperature coefficient is negative when viewed from the output end.

That is, a pair of NPN transistors Q1. In a differential amplifier circuit having transistor Q2, when the temperature rises for some reason and the collector current of transistor Q2 increases, the potential at the output terminal a1 of transistor Q2 decreases.

However, the forward voltage Vf of the n diodes D1 to Dn changes depending on the temperature, and as the temperature rises, Vf decreases, so the base voltage of the transistor Q3 is kept constant, and therefore the output voltage Vo is also kept constant. .

FIG. 2 shows an example of the same conventional temperature compensation circuit in which the temperature coefficient is positive when viewed from the output end.

That is, a pair of transistors Q1. In the differential amplifier circuit having transistor Q2, when the load current of transistor Q2 decreases due to an increase in temperature due to some reason, the potential at the output terminal a1 of transistor Q2 increases.

Then, the potential at point b1 of the emitter of transistor Q14 also rises, but the potential at the base of n PNPNPN transistors n increases.
Since the emitter voltage VBE becomes small, the transistor n
The base voltage of is made constant, and therefore the output voltage Vo is also made constant.

However, in conventional circuits such as those shown in FIGS. 1 and 2, the signal passes through the inserted temperature compensation circuit, resulting in poor circuit characteristics, particularly poor frequency characteristics and waveform distortion.

Furthermore, since temperature compensation is performed using the temperature dependence of Vf of a plurality of diodes or transistors, the temperature coefficient can only be selected in stages.

The present invention has been made in view of the above-mentioned circumstances, and its object is to provide a constant current type temperature compensation circuit which eliminates the above-mentioned drawbacks.

The present invention will be described in detail below with reference to the drawings.

FIG. 3 shows an embodiment in which the temperature coefficient is negative when viewed from the output end.

In the figure, Q31 and Q3□ are a pair of transistors included in the differential amplifier circuit 31, and the base of the transistor Q31 is connected to the input terminal 32 via the resistor R1.
The base of 3□ is connected to the input terminal 32 via a resistor R2 and is grounded via a capacitor C.

Transistor Q31. The emitters of Q3□ are commonly connected and grounded via resistor R3.

The collector of the transistor Q31 is connected to the power supply terminal 33 to which the power supply voltage Vc is supplied, and the collector of the transistor Q32 is connected to the power supply terminal 33 via the load resistor RA driven by the transistor Q3□, and the base of the transistor Q34. It is connected to the.

The collector of transistor Q34 is connected to power supply terminal 33, and the emitter of transistor Q34 is connected to output terminal 34 and grounded via resistor R4.

The circuit surrounded by the dotted line is a temperature compensation circuit, and the collector of the NPN transistor Q33 of this temperature compensation circuit 35 is connected to the output terminal of the driving transistor Q32 of the load resistor RA, that is, the point aat, and the emitter of the transistor Q33 is connected to the output terminal of the driving transistor Q32 of the load resistor RA. is grounded through resistor RB, and transistor Q3
The base of No. 3 is connected to the power supply terminal 33 via a resistor Rc, and is grounded via n diodes D31 to D3o connected in series in the forward direction.

In the circuit configured as described above, if we consider a case where the temperature rises for some reason and the collector current of the transistor Q32 increases, the rise in temperature causes the diode D to increase.
Since each forward voltage Vf of 31 to D3n also decreases, the base potential of transistor Q33 decreases.

Then, the current flowing between the collector and emitter of the transistor Q33 also decreases, so that the current flowing through the load resistor RA can be made constant, and the potential at the 833 points can be made constant, so that the output voltage at the output terminal 34 is reduced.

It is possible to prevent fluctuations due to temperature.

FIG. 4 shows another embodiment of the present invention, in which the temperature coefficient is positive, contrary to the case of FIG.

Regarding the configuration of this circuit, the diode D31 in FIG.
~D3n is replaced with bias resistor Ro, and diode D
31 to D3n are connected to the emitter of transistor Q33 and resistor R.
It is inserted between B and B, and only a part of the temperature compensation circuit 41 is different, and the other parts are the same as in FIG. 3, so corresponding parts are given the same symbols and explanations are omitted. do.

The operation of this circuit is such that when the temperature rises for some reason and the collector current of the transistor Q32 decreases, the forward voltage Vf of each of the diodes D3] to I)an also decreases due to the temperature rise. collector of
The current flowing between the emitters increases and therefore the load resistance RA
Since the current flowing through the output terminal 34 can be made constant, the output voltage of the output terminal 34 is constant.

It is possible to prevent fluctuations due to temperature.

In the circuit shown in FIGS. 3 and 4, the transistor Q
The impedance seen from the collector of 33 is very high (
(constant current type), the temperature compensation circuit has almost no effect on the load of transistor Q32.

Furthermore, since the signal passes directly from the collector of transistor Q32 to the base of transistor Q34, no signal passes through the temperature compensation circuit, and therefore the circuit characteristics are maintained well.

Further, the voltage at 331 points in FIG. 4 changes by JV when a temperature compensation circuit is inserted, and the change with respect to temperature is as follows. By changing the ratio of the resistors RA t RB, an arbitrary temperature coefficient can be obtained.

Therefore, if the voltage fluctuates by JV at 231 points, it is possible to compensate for the temperature by JV using the temperature compensation circuit.

FIG. 5 is a temperature T-JV relationship diagram of the circuits of FIGS. 3 and 4. FIG.

an NPN transistor whose collector side is connected between the output terminal of the load resistance driving element and the base of the transistor to which the output signal is input; and a resistor provided between the emitter of this transistor and a ground terminal; It is characterized by comprising a bias circuit that connects an impedance element and a diode in series between a power supply terminal and a ground terminal, and connects the impedance element and the diode to the base of the transistor, and also for driving a load resistance. an NPN transistor whose collector side is connected between the output terminal of the element and the base of the transistor to which the output signal is input; a diode and a resistor connected in series between the emitter of this transistor and the ground terminal; Since the device is characterized in that it includes a bias circuit connected to the base of the transistor, good circuit characteristics and an arbitrary temperature coefficient can be obtained.

Therefore, of course, the temperature coefficient of the output voltage ■o can be made zero, and for example, if a circuit with a temperature coefficient of Thus, a temperature compensation circuit can be provided which has advantages such as being able to arbitrarily adjust the temperature coefficient of the output voltage VO.

[Brief explanation of the drawing]

1 and 2 are conventional temperature compensation circuit diagrams, FIG. 3 is a circuit diagram of one embodiment of the present invention, FIG. 4 is a circuit diagram of another embodiment of the present invention, and FIG. 5 is a T- , is a JV relationship diagram. RA, Rn...Resistor, Q33...Transistor.

Claims (1)

[Claims] 1. An NPN transistor whose collector side is connected between the output terminal of a load resistance driving element and the base of a transistor into which the output signal is input, and between the emitter of this transistor and a ground terminal. and a bias circuit that connects an impedance element and a diode in series between a power supply terminal and a ground terminal, and connects the impedance element and the diode to the base of the transistor. Constant current type temperature compensation circuit. 2. An NPN transistor whose collector side is connected between the output terminal of the load resistance driving element and the base of the transistor into which the output signal is input, and a diode connected in series between the emitter of this transistor and the ground terminal. A constant current type temperature compensation circuit comprising: a resistor; and a bias circuit connected to the base of the transistor.