JP3066803B2 - Bias power supply circuit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bias power supply for supplying a predetermined bias voltage, and particularly to a bias power supply having a predetermined temperature-dependent characteristic.

[Prior Art] There are many cases where a predetermined bias voltage is required in an integrated circuit inside an IC or the like. In such a case, the simplest method is a method using resistance division. That is, a method in which two resistors are connected in series between a power supply and an earth, and a predetermined voltage is output from the intermediate point to divide the power supply voltage and output it as a bias voltage. According to this method, a desired bias voltage can be obtained according to the ratio of the resistance values of the two resistors.

However, in the method using the resistance division, when the power supply voltage fluctuates, the bias voltage fluctuates. In a circuit that requires a bias voltage, the value of the bias voltage often greatly affects its characteristics, and there is a demand for minimizing the fluctuation.

Therefore, various constant voltage circuits are used. Among these, the bandgap constant voltage circuit is widely used as a constant voltage source because it can supply a constant voltage and its temperature dependence can be made substantially zero.

As a constant voltage source, a Zener diode that conducts at a predetermined breakdown voltage or more is also used. However, since the Zener diode has a relatively high breakdown voltage of about 5 to 6 V, the power supply voltage is low. Is used in cases where is relatively high. Since the Zener diode has a temperature-dependent characteristic, the output voltage depends on a temperature change as it is. Therefore, in many cases, diodes are connected in series to cancel the temperature-dependent characteristics.

FIG. 3A shows an example of these constant voltage circuits.
(B) and (C) show. FIG. 3 (A) is an example of a constant voltage circuit using resistance division, FIG. 3 (B) is an example of a band gap constant voltage circuit, and FIG. 3 (C) is an example of a constant voltage circuit using a Zener diode. It is.

[Problems to be Solved by the Invention] As described above, various types of constant voltage circuits have been conventionally proposed and used. As described above, in a normal case, it is often desirable to have no temperature-dependent characteristic.

However, depending on the circuit that requires the bias voltage,
In some cases, it is desirable to have a predetermined temperature-dependent characteristic.
In particular, in an integrated circuit such as an IC, since a circuit is often formed by a semiconductor element, the circuit itself operates according to a voltage that varies with temperature. Therefore, it is better for the voltage supplied here to have similar temperature-dependent characteristics.

For example, in a constant current circuit as shown in FIG.
It is preferable that the voltage _{VREF of the} bias source has a predetermined temperature-dependent characteristic.

That is, this circuit, a current mirror consisting of transistors Q _1, Q ₂ - flowing through the same current flowing through the transistor Q ₁ side current in the transistor Q ₂ side, it is intended to flow out a constant current from the electric circuit Ci .

The current I in this circuit is represented by I = (V _REF −2 · V _F ) / (R ₁ + R ₂ ). Here, V _F is the transistor Q _1, Q ₂ base - scan, an emitter voltage.

The transistor usually has a temperature dependence of about -1.8 mV / ° C. Transistor base - Suemitta voltage V _F is located approximately 0.7～0.8V, voltage change due to temperature change of 50 ° C. Since the 0.09 V, the change of the current I due to the temperature change becomes quite large . The electric circuit Ci responds to twice the voltage change ΔV _F (2 · V _F ) based on the temperature-dependent characteristics of the transistors Q ₁ and Q _2.
The current I flowing out of the device fluctuates. In such a case, it is desired to provide the bias voltage V _REF with a temperature characteristic that cancels the temperature-dependent characteristics of the transistors Q ₁ and Q ₂ .

FIG. 4 shows a configuration example of the differential amplifier. In this example, the input signal IN via the transistor Q _4, Q ₅ which forms an emitter follower, a pair of differential amplifier transistors Q _6, Q ₇ of base - but always supplied to the scan,
The potential at the connection point of the differential amplifier transistors Q _6, Q ₇ and the constant current source I0 will depend on the differential amplifier transistors _{Q 4, Q 5, Q 6} , Q 7 temperature characteristics.

While the constant current source I ₀ is intended supplies a constant current regardless of the potential change of the upstream side, it is preferable that the potential of the upstream side does not change. In particular, when the potential on the upstream side falls below a predetermined constant voltage, the constant voltage circuit may not function properly. In many cases, the bias voltage V _REF must be suppressed to a relatively low level in relation to the power supply voltage. In such a case, the transistors Q ₄ , Q ₅ , Q ₆ , Q ₇
It is desired to provide such a temperature-dependent characteristic that cancels out the temperature-dependent characteristic.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and provides a bias power supply circuit for supplying a bias voltage having a predetermined temperature-dependent characteristic, and a constant current circuit and an amplifier using the bias voltage. It is intended to realize a circuit.

Means for Solving the Problems In order to achieve the above object, according to a first aspect of the present invention, a current mirror circuit provided on a substrate of an integrated circuit and a current mirror circuit provided on the same substrate as the current mirror circuit are provided. A bias voltage circuit for supplying a predetermined bias voltage to the current mirror circuit, wherein the bias voltage circuit outputs a constant voltage having substantially no temperature-dependent characteristics. A constant voltage circuit, a voltage dividing means connected to the output side of the constant voltage circuit and comprising two resistors connected in series, and a base connected to an intermediate point between the two resistors of the voltage dividing means. The collector is connected to the ground and the emitter is connected to the power supply.
A PNP transistor, and an output terminal connected to the emitter side of the PNP transistor and outputting a bias voltage, wherein a temperature characteristic of the PNP transistor and a temperature characteristic of the current mirror circuit cancel each other. It is a characteristic constant current circuit.

According to a second aspect of the present invention, there is provided a differential amplifier circuit provided on a substrate of an integrated circuit, and a bias voltage circuit provided on the same substrate as the differential amplifier circuit. A bias voltage circuit for supplying a predetermined bias voltage, wherein the bias voltage circuit outputs a constant voltage having substantially no temperature-dependent characteristics, and an output side of the low voltage circuit. And a voltage dividing means composed of two resistors connected in series,
The base is connected to the midpoint between the two resistors, and the collector is grounded.
A PNP transistor for temperature characteristics imparting, the emitter of which is connected to a power supply, and an output terminal connected to the emitter side of the PNP transistor for outputting a bias voltage, wherein the differential amplifier circuit Is an amplifier circuit including an NPN transistor, wherein a temperature characteristic of the PNP transistor and a temperature characteristic of the differential amplifier circuit cancel each other.

According to a third aspect of the present invention, in the constant current circuit according to the first aspect of the present invention, the voltage dividing means includes a first diode connected in series with the two resistors, A constant current circuit, wherein a temperature characteristic of the first diode and a temperature characteristic of the current mirror circuit cancel each other.

According to a fourth aspect of the present invention, in the amplifier circuit according to the second aspect of the present invention, the voltage dividing means includes a first diode connected in series with the two resistors, and the PNP transistor and the first Wherein the temperature characteristics of the diode and the temperature characteristics of the differential amplifier circuit cancel each other.

According to a fifth aspect of the present invention, in the constant current circuit according to the first or third aspect of the present invention, a second diode connected between the emitter of the PNP transistor and the output terminal is further provided. A temperature characteristic of one of the temperature characteristics of the PNP transistor and the first and second diodes, or a temperature characteristic of the PNP transistor and the first and second diodes; and the current mirror circuit. The constant current circuit is characterized in that the temperature characteristics of the constant current circuit cancel each other.

A sixth aspect of the present invention is the amplifier circuit according to the second or fourth aspect, further comprising a second diode connected between the emitter of the PNP transistor and the output terminal. , The PNP transistor and the first
And that the temperature characteristics of any one of the temperature characteristics of the PNP transistor and the first and second diodes and the temperature characteristics of the differential amplifier circuit cancel each other. It is a characteristic amplifier circuit.

[Operation] A constant voltage having substantially no temperature-dependent characteristic is converted into a predetermined voltage by a voltage dividing resistor and supplied to a PNP transistor for providing a temperature characteristic. Then, a bias voltage is output from the emitter side of the PNP transistor. For this reason, the output bias voltage is set to a predetermined voltage by the voltage dividing resistor, and is provided with a temperature characteristic required for an electric circuit on the same substrate corresponding to the PNP transistor. Further, since a PNP transistor is used, an unnecessary current does not flow into the voltage dividing resistor, and a predetermined bias voltage can be output.

If a diode or the like is further added to this circuit,
Temperature dependent characteristics can be changed.

Then, a constant current circuit is formed by supplying the above-described predetermined bias voltage to the current mirror circuit. With such a configuration, the temperature characteristics of the bias voltage and the temperature characteristics of the current mirror cancel each other. The temperature characteristics of the current mirror (final characteristics including the temperature characteristics of the bias voltage) can be freely adjusted by the resistance ratio, the type of the current mirror, and the like.

The amplifier circuit is configured by supplying the predetermined bias voltage to the difference amplifier circuit. According to this configuration, the temperature characteristics of the PNP transistor and the NPN transistor cancel each other due to the circuit configuration. Further, according to the configuration of the present invention, the dynamic range (maximum allowable amplitude) is improved.

Hereinafter, a bias power supply circuit according to the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram showing a bias power supply circuit according to one embodiment of the present invention.

Substantially band gap constant voltage circuit 10 is independent of temperature characteristics constant voltage source outputting a constant voltage V _00. The output side of this band gap constant voltage circuit 10 is a transistor
It is connected to 12 bases. The emitter of the transistor 12 is connected to the ground via a constant current source 16 together with the emitter of the transistor 14 disposed so as to face the transistor 12. The collectors of the transistors 12 and 14 current mirror - is connected to a power supply V _CC through a transistor 18 and 20 constituting the.

The base of the transistor 14 is connected to the base of the transistor 24 via the capacitor 22.
The collector of 24 is connected to the power supply V _CC , and the emitter is connected to the ground via two series-connected resistors 26 and 28. The connection point between the collectors of the transistors 20 and 14 is connected to the connection point between the base of the transistor 24 and the capacitor 22, and the connection point between the resistors 26 and 28, the transistor 14 and the capacitor.
22 connection points are connected.

Connection point b of the transistor 24 and the resistor 26 and outputs a voltage V _0, this is the connection point b die - anode de 30 - De is connected, the diode - de 30 cathode - de partial pressure Resistance 3
It is grounded via 2,34.

The connection point of these voltage dividing resistors 32 and 34 is a PNP transistor 3
6 PNP type transistor 36
The collector is grounded, and the emitter is connected to a power supply V _CC via a diode 38 and a resistor 40. The bias voltage _VREF is output from between the resistor 40 and the diode 38.

In such a circuit, a band gap constant voltage circuit
10 predetermined constant voltage V ₀₀ does not vary with variations and temperature variations of the power supply voltage V _CC from is output. This constant voltage V ₀₀
Is determined by the transistors, resistors, and the like constituting the bandgap constant voltage circuit. In order to remove the temperature-dependent characteristics, these combinations must be set to a predetermined value, and the output voltage V _CC is limited to about 1.2V.

The constant voltage _V00 is output as a voltage V _O which is higher than the point b after receiving a predetermined boosting action. Transistor 12
Receives a constant voltage _{V00 and} passes a constant current therethrough. In response, the same current flows through transistors 18 and 20 forming a current mirror disposed upstream thereof.

Then, the current flowing through the transistor 14 is
The sum of the currents flowing through 12 is kept constant by the constant current source 16. Here, the collector side of the transistor 20 is connected to the base of the transistor 24, and the potentials of both are equal. Further, the base potential of the transistor 14 is
And is maintained at the potential here.

Therefore, it is possible to determine the voltage V ₀ at the connection point b according to the size ratio of resistors 26 and 28. Then, the voltage V ₀ is lower than the power supply voltage V _CC, it can be a predetermined high voltage.

Next, a voltage dividing resistor 3 is connected to the connection point b through a diode 30.
2, 34 is connected, in accordance with these values, base of the PNP transistor - supplying the predetermined to the scan voltage V _1. That is, the voltages V ₁ is diode - voltage de 30 drop V _F and the resistor 32,
According to the resistance values R32 and R34 of 34, it becomes as follows.

_{V 1 = (V 0 -V F} ) · R 34 / (R 32 + R 34) For example, if V ₀ is 4V, V _F is 0.75 V, the resistance value of R ₃₂ and R ₃₄ are the same, the V ₁ becomes 1.625V.

The base of the PNP transistor 36 - so the ground potential is V _1, this of the PNP transistor 36 base - Suemitta voltage V _F and diode - bias voltage the voltage drop V _F of the de 38 is summed voltage V _REF Is output as

Here, characteristic feature in this embodiment, the bias voltage V _REF to be output PNP transistor 36 and diode - it is to have a one corresponding to V _F of the de 30, 38. Therefore, the bias voltage V _REF becomes possible to vary according to the temperature dependence of V _F of these semiconductor devices.

That is, V _REF = V ₁ + 2V _F , and V ₁ includes V _F as described above. Therefore, when the resistance values of the resistors 32 and 34 are 1: 1, the bias voltage V _REF is , 1.5V _F. Therefore, a temperature characteristic corresponding to the 1.5 V _F is applied to the bias voltage V _REF . Such temperature characteristics can be arbitrarily adjusted according to the number of diodes 30 and 38 to be inserted and arranged.

Further, since it arbitrarily adjust the V ₁ by adjusting the value of the resistor 32 and 34, it is possible to set the bias voltage V _REF to a desired value. In the normal case, the diode
If 30 is omitted, the temperature characteristics are not changed by the resistors 32 and 34. Therefore, it is preferable to omit this and adjust the temperature characteristics by the number of diodes 38.

Here, in the above description, diodes 30, 38,
Describing the V _F of the transistor 36 as the same value. This is because, in an integrated circuit, these semiconductor elements are formed on the same substrate and have the same value unless their specifications are significantly different.

The circuit for requesting other bias voltage formed on the same substrate also has a similar semiconductor device, the temperature characteristics are also required in many cases to be those corresponding to the same V _F. Therefore, by increasing or decreasing the number of diodes 38 connected in series, it is possible to meet the demand for providing temperature characteristics in many cases.

Note that diodes in such integrated circuit - de Baie - scan, may utilize transistors shorted connection between the collector more usually base - Suemitta voltage becomes the voltage drop V _F.

The reason why the PNP transistor is adopted as the transistor 36 is to prevent a current flowing from the diode 38 from flowing into the resistor 34. That is, if a PNP transistor is used, the current flowing through the resistor 34 can be limited to a base current or a predetermined small current, and a desired bias voltage _VREF can be obtained.

FIG. 2 shows a modification of the bias voltage output unit. In this example, a diode 50 is arranged on the emitter side of the PNP transistor 36 in addition to the diode 38. Therefore, the point c on the upstream side of the diode 50
Are the PNP transistor 36, diodes 38, 5
It corresponds to a voltage drop of 3V _{F of} 0. Therefore, the voltage at this point c has a temperature-dependent characteristic corresponding to 3V _F.

However, this point c is connected to the base of a transistor 52 forming an emitter follower, the collector of this transistor 52 is connected to the power supply _VCC , and the emitter is grounded via a constant current source 54. The bias power supply V _REF is taken out from the upstream side of the constant current source. Therefore, the bias voltage V _REF is composed of the potential at the point c and minus the V _F of the transistor 52. Accordingly, the bias voltage V _REF in this example has a temperature characteristic corresponding to 2V _F.

The addition of the emitter follower can increase the current supply capability of the bias power supply V _REF, and is particularly suitable for increasing the current supply.

Further, a plurality of such circuits can be connected to point b in FIG. By connecting a plurality of circuits, a bias power supply having a plurality of types of temperature characteristics can be obtained, and a bias voltage of a desired voltage having a desired temperature characteristic of a plurality of electric circuits can be supplied.

Further, the bias circuit according to the present invention is not limited to the above-described example, and can be suitably applied to all circuits requiring a constant voltage source having temperature characteristics. Further, as a constant voltage circuit having substantially no temperature characteristic, a circuit using a Zener diode shown in FIG. 3C can be employed.

[Effects of the Invention] As described above, according to the bias circuit of the present invention, the bias power supply can be set to a desired voltage and a desired temperature-dependent characteristic can be imparted thereto. Therefore, a desired temperature characteristic according to the temperature characteristic of the semiconductor element required in the electric circuit on the same integrated circuit can be given to the bias voltage.

As a result, a constant current circuit with improved temperature characteristics and an amplifier circuit with improved dynamic range can be provided.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a bias power supply circuit according to one embodiment of the present invention, FIG. 2 is a circuit diagram showing another embodiment, FIG. 3 is a circuit diagram showing a constant voltage circuit, FIG. FIG. 5 is a circuit diagram showing an example of an electric circuit requiring a temperature characteristic. 10 …… Band gap constant voltage circuit 32,34 …… Division resistor 36 …… PNP transistor

Claims (6)

(57) [Claims] A current mirror circuit provided on a substrate of an integrated circuit; and a bias voltage circuit provided on the same substrate as the current mirror circuit, wherein a predetermined bias voltage is supplied to the current mirror circuit. A bias voltage circuit, comprising: a constant voltage circuit that outputs a constant voltage having substantially no temperature-dependent characteristics; a constant voltage circuit that is connected to an output side of the constant voltage circuit, and is connected in series. Done 2
A voltage dividing means composed of two resistors, a base connected to an intermediate point between the two resistors of the voltage dividing means, a collector connected to the ground, and an emitter connected to the power supply for providing a temperature characteristic PNP. And an output terminal connected to the emitter side of the PNP transistor and outputting a bias voltage, wherein a temperature characteristic of the PNP transistor and a temperature characteristic of the current mirror circuit cancel each other. Constant current circuit. 2. A differential amplifier circuit provided on a substrate of an integrated circuit, and a bias voltage circuit provided on the same substrate as the differential amplifier circuit, wherein a predetermined bias voltage is applied to the differential amplifier circuit. And a bias voltage circuit that supplies a constant voltage circuit that outputs a constant voltage having substantially no temperature-dependent characteristic; and a bias voltage circuit that is connected to an output side of the constant voltage circuit. 2 connected in series
A voltage dividing means comprising two resistors, a base connected to an intermediate point between the two resistors of the voltage dividing means, a collector connected to the ground, and an emitter connected to the power supply; An output terminal connected to the emitter side of the PNP transistor and outputting a bias voltage.The differential amplifier circuit includes an NPN transistor, and a temperature characteristic of the PNP transistor; An amplifier circuit characterized in that the temperature characteristics of the differential amplifier circuit cancel each other. 3. The constant current circuit according to claim 1, wherein said voltage dividing means includes a first diode connected in series with said two resistors, wherein said PNP transistor and said second diode are connected in series. A temperature characteristic of the diode and a temperature characteristic of the current mirror circuit cancel each other. 4. The amplifier circuit according to claim 2, wherein said voltage dividing means includes a first diode connected in series with said two resistors, said PNP transistor and said first diode. Wherein the temperature characteristic of the diode and the temperature characteristic of the differential amplifier circuit cancel each other. 5. The constant current circuit according to claim 1, further comprising: a second diode connected between an emitter side of said PNP transistor and said output terminal. Temperature characteristics of either the PNP transistor and the first and second diodes, or the temperature characteristics of the PNP transistor and the first and second diodes, and the current mirror A constant current circuit characterized by canceling out the temperature characteristics of the circuit. 6. The amplifier circuit according to claim 2, further comprising: a second diode connected between an emitter of said PNP transistor and said output terminal. Temperature characteristics of either the PNP transistor and the first and second diodes, or the temperature characteristics of the PNP transistor and the first and second diodes, and the differential amplification An amplifier circuit wherein the temperature characteristics of the circuit cancel each other.