JP3142704B2 - Amplifier circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an amplifier circuit. In recent years, electronic devices tend to require more and more accurate operations. Therefore, high-precision operation is required also in an amplifier circuit used in such an electronic device.

[0002]

2. Description of the Related Art FIG. 6 is a block circuit diagram of a conventional non-inverting amplifier circuit. An amplifier circuit 40 includes an input circuit section 41 and a feedback circuit section 42. Input circuit 41 inputs at its non-inverting input terminal signal V _in1, receives the input signal V _in2 to the inverting input terminal, and outputs a current corresponding to the input signal V _in1, V _in2 the feedback circuit unit 42. Feedback circuit section 4
2 generates and outputs an output signal _Vout based on the input current.

The amplification degree AV of the amplification circuit 40 is defined as the product of the amplification degree AVa and the amplification degree AVb (AVa · AVb), where AVa is the amplification degree of the input circuit section 41 and AVb is the amplification degree of the feedback circuit section 42. ).

In some cases, output signals V _out1 and V _out2 having the same amplification factor and the same or opposite phases are required. FIG. 7 shows the configuration of an amplifier circuit for obtaining an in-phase output. This amplifier circuit 43 uses two amplifier circuits 43a and 43b as a non-inverting amplifier circuit. That is, the amplifier circuits 43a,
The input circuit portions 41a and 41b of 43b both _{receive the} input signal _Vin1 at their non-inverting input terminals and the input signal Vin at their inverting input terminals.
Enter _in2 . Then, the amplifier circuits 43a and 43b output in-phase output signals V _out1 and V _out2 from the feedback circuit units 42a and 42b, respectively.

FIG. 8 shows a configuration of an amplifier circuit for obtaining an output of the opposite phase. This amplifying circuit 43 uses one amplifying circuit 43a as a non-inverting amplifying circuit and uses the other amplifying circuit 43b as an inverting amplifying circuit with respect to the two amplifying circuits 43a and 43b. That is, the input input circuit portion 41a of the amplifier circuit 43a is in its non-inverting input terminal signal V _{in 1}
And the input signal _Vin2 is input to the inverting input terminal. on the other hand,
The input signal V _in2 input circuit section 41b at its non-inverting input terminal of the amplifier circuit 43 b, an inverting input terminal signal V _in1
Enter Accordingly, the amplifier circuits 43a and 43b output output signals V _out1 and V _out2 having opposite phases from the feedback circuit sections 42a and 42b, respectively.

[0006]

However, the above-mentioned 2)
In order to obtain different types of output signals V _out1 and V _out2 , two amplifier circuits 43a and 43b, that is, two input circuit units 41a and 41b and two feedback circuit units 42a and 42b are required. Therefore, there is a problem that more elements are required and the circuit scale becomes large when viewed from the whole of the amplifier circuit 43.

Although it is assumed that the input circuit sections 41a and 41b and the feedback circuit sections 42a and 42b are formed identically, they cannot be formed identically in a manufacturing process. Variations were inevitable.

Accordingly, both the input circuit section 41a, 41b to each other relative error and both the feedback circuit 42a, that the relative error of 42b with each other is appearing in the output signal V _{ou t1,} V _out2 as a larger error by the product problem was there.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to reduce the number of constituent elements and to improve the relative accuracy of a plurality of outputs. Is to provide.

[0010]

FIG. 1 is a diagram illustrating the principle of the present invention. The amplifier circuit includes an input circuit unit 1 and a plurality of feedback circuit units 2 for the input circuit unit 1. Input circuit unit 1 includes first and second N with a pair of first and second collector of the NPN transistor Tr3, Tr6 are constant current driven through the first resistor R1 are connected to each other
The emitters of the PN transistors Tr3 and Tr6 are connected to a second resistor R
Via 2 connected to each other, the input signal V _in1 to the first and second PNP transistors Tr3, Tr6 emitter, V _in2
And output currents I _O1 and I _O1 , from both terminals of the first resistor R1.
Outputs I _O2 .

The plurality of feedback circuit units 2 input the output currents I _O1 and I _O2 to the emitters of a pair of first and second PNP transistors Tr11 and Tr13, respectively, and output the first and second PNP transistors Tr11 and Tr11. The collector of Tr13 is connected to the collectors of a pair of third and fourth NPN transistors Tr12 and Tr14 forming a current mirror circuit, respectively. The reference voltage _Vref1 is input to the base of the first PNP transistor Tr11. PNP transistor Tr11
Connect the operational amplifier OP1 to the collector of the connection is between the outputs the output signal V _out1 from the operational amplifier circuit OP1, the output signal V _out1 and the reference voltage V _ref1
And the connection point is the second PNP transistor Tr13
And fifth resistors R11 and R13 connected to the base of the
And a fourth resistor connected between the connection point and the ground.
Anti-R12 .

[0012]

Therefore, according to the present invention, a plurality of feedback circuit sections 2 are connected to the input circuit section 1 and the first
And a second PNP transistor Tr11, Tr 13 of the output current I _O1 of the input circuit section 1 to the emitter, since the I _O2 to enter each of the two phase with the pair of the input signal V _in1, V _in2 output The signal V _out1 can be obtained. Moreover, an increase in the number of elements in the amplifier circuit can be suppressed. Further, since the input circuit unit 1 is common to the plurality of feedback circuit units 2, the relative error of the output signal V _out1 output from each feedback circuit unit 2 can be reduced, and the relative accuracy can be improved. it can.

[0013]

FIG. 2 shows an embodiment of the present invention.
This will be described with reference to FIG. FIG. 2 is a block diagram of the amplifier circuit 10. The amplifier circuit 10 includes an input circuit section 11 and feedback circuit sections 12a and 12b.

[0014] The input signal V _in1 at the input circuit section 11 includes the non-inverting input terminal, inverting the input signal V _in2 at the input terminal, on the basis of the preset amplification factor of both the input signal V _in1, V _in2 The signal is amplified and output to the feedback circuit units 12a and 12b, respectively.

One feedback circuit 12a is connected to the input circuit 11
, And generates and outputs an output signal V _out1 obtained by amplifying the input based on a preset amplification factor.

The other feedback circuit 12b is connected to the input circuit 11
And outputs an output signal _Vout2 obtained by amplifying the input based on a preset amplification factor. The feedback circuit unit 12b outputs the output signal V
_out2 is connected so that the output of the output signal V _out1 and phase of the other of the feedback circuit portion 12a.

Next, the input circuit section 11 and the feedback circuit section 12
The detailed configuration of a and 12b will be described with reference to FIG. FIG.
Is an input circuit section 11 and a feedback circuit section 12 of the amplifier circuit 10.
It is a circuit diagram which materialized a and 12b, respectively. The input circuit section 11 includes PNP transistors Tr1 and Tr4, NPN transistors Tr2, Tr3, Tr5 and Tr6, resistors R1 and R2, and constant current sources S1 to S6. The base of the PNP transistor Tr1 receives an input signal _Vin1 input to the input circuit unit 11 via the non-inverting input terminal.
The emitter of the transistor Tr1 is an NPN transistor T
The collector of the transistor Tr1 is connected to the ground GND.

The collector of the transistor Tr2 is supplied with a collector current from a power supply Vcc via a constant current source S1. An NPN transistor T is connected to the constant current source S1.
The base of r3 is connected to supply a base current from the identification current source S1, and the collector of the transistor Tr3 has a power supply V
A collector current is supplied from cc via a constant current source S2. The emitter of the transistor Tr3 is connected to the base of the transistor Tr2 and to the ground GND via a constant current source S3.

On the other hand, the base of the PNP transistor Tr4 inputs an input signal _Vin2 input through an inverting input terminal. The emitter of the transistor Tr4 is connected to the emitter of an NPN transistor Tr5.
The collector of r4 is connected to the ground GND.

The collector of the transistor Tr5 is supplied with a collector current from a power supply Vcc via a constant current source S4. The constant current source S4 has an NPN transistor T
The base of the transistor Tr6 is connected to supply a base current from the identification current source S4.
A collector current is supplied from cc via a constant current source S5.

The emitter of the transistor Tr6 is connected to the base of the transistor Tr5 and to the ground GND via a constant current source S6. The collectors of the transistors Tr3 and Tr6 are connected via a resistor R1, and the emitters of the transistors Tr3 and Tr6 are connected via a resistor R2.

[0022] Then, output the current I _O1, I _O2 based from both ends to the input signal V _in1, V _in2 of said resistor R1 feedback circuit portion 12a, the 12b. First, the feedback circuit section 12a will be described in detail. The feedback circuit unit 12a is a PNP
Transistors Tr11, Tr13, Tr15, Tr16, NPN
Transistors Tr12 and Tr14, diodes D11 and D12,
Resistors R11 to R13, operational amplifier circuit OP1, and constant current source S
11 and S12. Then, the input circuit unit 1
The current _IO1 output from ₁ is a PNP transistor Tr11
Is input to the emitter, current I _O2 is input to the emitter of the PNP transistor Tr 13.

The base of the PNP transistor Tr11 is connected to the anode of the diode D11. Diode D
A forward current is supplied to the anode of the diode D11 from a power supply Vcc via a constant current source S11.
It is connected to the emitter of the NP transistor Tr15.
The reference voltage _Vref1 is input to the base of the transistor Tr15, and the collector is connected to the ground GND.

The base of the PNP transistor Tr13 is connected to the anode of the diode D12. A forward current is supplied to the anode of the diode D12 from the power supply Vcc via the constant current source S12, and the cathode of the diode D12 is connected to the emitter of the PNP transistor Tr16.

A voltage V _ref2 from a reference voltage V _ref1 via a resistor R 11 is input to the base of the transistor Tr 16, and the collector of the transistor Tr 16 is connected to the ground GND.
It is connected to the. The collectors of the transistors Tr11 and Tr13 are respectively connected to the collectors of a pair of NPN transistors Tr12 and Tr14 forming a current mirror.

The collector of the transistor Tr12 is connected to the inverting input terminal of the operational amplifier OP1, and the non-inverting input terminal is connected to the ground GND. An output signal V _out1 is output from an output terminal of the operational amplifier circuit OP1,
The output terminal is connected to the transistor Tr16 via a resistor R13.
Connected to the base. A resistor R12 is connected between the connection point of the resistors R11 and R13 and the ground GND.

Next, the configuration of the feedback circuit section 12b will be described.
I will tell. The feedback circuit section 12b includes a PNP transistor Tr2
1, Tr23, Tr25, Tr26, NPN transistor Tr2
2, Tr24, diodes D21, D22, resistors R21 to R23,
It comprises an operational amplifier circuit OP2 and constant current sources S21 and S22.
Has been established. Current I output from input circuit section 11 _O1
Is input to the emitter of the PNP transistor Tr21,
Style I_O2Is input to the emitter of the PNP transistor Tr23.
Have been.

The feedback circuit section 12b has the same circuit configuration as the feedback circuit section 12a, and uses the same elements. That is, the base of the PNP transistor Tr21 is connected to the anode of the diode D21. A forward current is supplied to the anode of the diode D21 from the power supply Vcc via the constant current source S21, and the cathode of the diode D21 is connected to the emitter of the PNP transistor Tr25. The reference voltage _Vref1 is input to the base of the transistor Tr25, and the collector is connected to the ground GND.

The base of the PNP transistor Tr23 is connected to the anode of the diode D22. A forward current is supplied to the anode of the diode D22 from the power supply Vcc via the constant current source S22, and the cathode of the diode D22 is connected to the emitter of the PNP transistor Tr26.

The base of the transistor Tr26 has a voltage Vref3 (= Vref3) from a reference voltage _Vref1 via a resistor R21.
_ref2 ) is input, and the collector of the transistor Tr26 is connected to the ground GND. Transistor Tr21
, Tr23 are connected to the collectors of a pair of NPN transistors Tr22, Tr24 forming a current mirror, respectively.

The collector of the transistor Tr22 is connected to the inverting input terminal of the operational amplifier OP2, and the non-inverting input terminal is connected to the ground GND. An output signal V _out2 is output from the output terminal of the operational amplifier circuit OP2,
The output terminal is connected to the base of the transistor Tr26 via a resistor R23. A resistor R22 is connected between the connection point of the resistors R21 and R23 and the ground GND.

As described above, the feedback circuit section 12a and the feedback circuit section 12b have the same circuit configuration. That is, the transistors Tr11 to Tr16 of the feedback circuit 12a
And the transistors Tr21 to Tr26 of the feedback circuit section 12b are formed in the same size and have the same electrical characteristics. Also,
Diodes D11, D12 and D2 of both circuit sections 12a, 12b
1 and D22 have the same size and the same electrical characteristics. The currents supplied from the constant current sources S11 and S12 are the same as the currents supplied from the constant current sources S21 and S22, and the operational amplifier circuit OP1 and the operational amplifier circuit OP
The amplification factors of 2 are the same. Further, the resistance values of the resistors R11 to R13 and the resistors R21 to R23 are formed to be the same. Therefore, the characteristics of the feedback circuit unit 12a and the feedback circuit unit 12b are also the same.

Next, the amplification circuit 1 configured as described above
The operation of 0 will be described. First, an output signal V _out1 output from the feedback circuit unit 12a with respect to the input signals V _in1 and V _in2 .
Will be described.

Each of the transistors Tr1 to Tr6, Tr11 to Tr11
The voltage drop between the base and emitter of Tr16 is VBET1 to VBET.
6, VBET11 to VBET16, and the forward voltage drops of the diodes D11 and D12 are VBED11 to VBED12.

The base potential of the transistor Tr2 is Va.
And then, when the potential difference between the input signal V _in1, V _in2 and _{ΔV in, Va = ΔV in +} V BET1 + V BET2 ─────────── (1) , and the base potential of the transistor Tr5 Vb Then, Vb = V _BET4 + V _BET5 ─────────── (2)

Further, the voltage between the two terminals of the resistor _{R2, Va -Vb = ΔV in ─────────── (} 3) , and therefore, the current flowing through the resistor R2 [Delta] I2 is, [Delta] I2 = [Delta] V _in / R2─────────── (4).

The emitter current of the transistor Tr3 is represented by IET3, and the current flowing through the constant current sources S3 and S6 is represented by IET3.
If it is set to 1, I _ET3 = I 1 + ΔI 2 ─────────── (5).

Here, the difference between the base current flowing through the transistor Tr2 and the base current flowing through the transistor Tr3 is sufficiently smaller than the emitter current IET3 of the transistor Tr3, so that the emitter current IEt3 of the transistor Tr3 and the transistor Tr3 _Are assumed to be equal, and I _ET3 = I _CT3 ─────────── (6).

On the other hand, the current output from the input circuit section 11, that is, the PNP transistor Tr1 of the feedback circuit section 12a
Current I _O1 flowing through the first emitter, a current flowing through the resistor R1 and .DELTA.I1, and the current does not flow to the transistor Tr3 of the output current I2 of the constant current source S2, and _{Ia, I a = I O1 -ΔI} 1 ─ ────────── (7) Then, I _ET3 + I _a = (I 1 + ΔI ₂ ) + (I _O1 −ΔI ₁ ) = I 2 ─────────── (8) Similarly, the emitter current I _{ET6 of the} transistor Tr6 becomes I _ET6 = I ₁ −ΔI ₂ ─────────── (9), and the current output from the input circuit section 11, that is, the current I _O2 flowing to the emitter of the PNP transistor Tr13 of the feedback circuit section 12a is When a current does not flow in the transistor Tr6 of the output current I2 of the constant current source S5, and Ib, the _{I b = I O2 + ΔI 1} ────────── (10). Then, I _ET6 + I _b = (I ₁ −ΔI ₂ ) + (I _O2 + ΔI ₁ ) = I 2 ────────── (11) The currents I _O1 , I flowing through the emitters of the transistors Tr11, Tr13 _O2 is given by I _O1 = I _O2 ────────── (12) by the feedback circuit section 12a.

Therefore, from equations (8), (11) and (12), ΔI ₂ = ΔI ₁ ────────── (13).

Here, the voltage between both terminals of the resistor R1 is ΔV _O
Then, ΔV _O = R1 · ΔI ₁ ────────── (14)

Therefore, from the equations (4) and (13), ΔV _O = R1 · ΔI ₂ = (R1 / R2) · ΔV _in ────────── (15) The gain AV11 of No. 11 is as follows: AV11 = ΔV _O / ΔV _in = R1 / R2────────── (16)

Therefore, since the gain AV11 of the input circuit section 11 is determined only by the resistance values of the resistors R1 and R2, its input / output characteristics are excellent in linearity. In addition, the reference voltages V _ref1 , V
relationship _ref2 becomes _{V ref1 + V BET15 + V BED11} + V BET11 + ΔV O -V BET13 -V BED12 -V BET16 = V ref2 ──────── (17).

Here, if V _BET15 = V _BET16 V _BED11 = V _BED22 V _BET11 = V _BET13 (18), V _ref2 = V _ref1 + ΔV _O ───── ───── (19) Here, when ΔVo = 0, the output signal V _out1
Becomes an output signal V _out1 (DC) which is a DC voltage, and V _ref1 =
V _ref2 . Therefore, V _ref1 / R 12 = (V _out1 (DC) −V _ref1 ) / R13──── (20). As a result, V _out1 (DC) = V _ref1 · (R12 + R13) / R12──── (21)

Next, the gain AV12a of the feedback circuit section 12a is obtained. First, when the variation amount of the output signal V _out1 and _{ΔV out1, ΔV O / R11 +} ΔV O / R12 = (ΔV out1 -ΔV O) / R13 ────────── (22) Thus, [Delta] V _{out1 / R13 = ΔV O · (1} / R11 + 1 / R12 + 1 / R13) ────────── (23) , and the gain AV12a of the feedback circuit portion 12a _{AV12a = ΔV out1 / ΔV O =} R13 · (1 / R11 + 1 / R12 + 1 / R13) = 1 + R13 · (R11 + R12) / (R11 · R12) ────────── (24)

Therefore, the output signals V _in1 and V _in2 input to the amplifier circuit 10 are output signals V in
_From the equations (16) and (24), the gain AV1 of _out1 is given by AV1 = ΔV _out1 / ΔV _in = (ΔV _O / ΔV _in ) · (ΔV _out / ΔV _O ) = AV 11 · AV 12a = (R 1 / R 2) · (1 + R 13・ (R11 + R12) / (R11 · R12)) ────────── (25)

Next, the gain AV12b of the feedback circuit section 12b is obtained. Since the feedback circuit section 12a has the same circuit configuration as the feedback circuit section 12a, the gain AV12b can be similarly obtained. That is, the variation of the output signal V _out2 is ΔV
_{Assuming out2} , ΔV _O / R 21 + ΔV _O / R 22 = (ΔV _out2 −ΔV _O ) / R 23 (26) Therefore, ΔV _out2 / R 23 = ΔV _O · (1 / R 21 +1) / R22 + 1 / R23) (27), and the gain AV12b of the feedback circuit section 12b is as follows: AV12b = 1 + R23 · (R21 + R22) / (R21 · R22) ─────── ─── (28)

Therefore, the output signal V in ₁ output with respect to the input signals V _in1 and V _in2 input to the amplifier circuit 10
_From the equations (16) and (28), the gain AV2 of _out2 is given by: AV2 = AV11 · AV12b = (R1 / R2) · (1 + R23 · (R21 + R22) / (R21 · R22))) ( 29)

The variation of the output signal V _out1 is represented by ΔV
When _out1, of the input signal V _in1, V _{in 2} potential difference ΔV _in
Variation [Delta] V _out1 for _{the, ΔV out1 = ΔV in · (} R1 / R2) · (1 + R13 · (R11 + R12) / (R11 · R12)) ────────── become (30).

The variation of the output signal V _out2 is represented by ΔV _out2
When the variation amount [Delta] V _out2 for the potential difference [Delta] V _in the input signal V _in1, V _{in2 is, ΔV out2 = ΔV in · (} R1 / R2) · (1 + R23 · (R21 + R22) / (R21 · R22)) ──── ────── (31)

Here, the feedback circuit section 12a and the feedback circuit section 1
2b has the same configuration and characteristics. Therefore, from equations (30) and (31), ΔV _out1 = ΔV _out2 ────────── (32).

As described above, in this embodiment, the amplification circuit 10
And the feedback circuit sections 12a and 12b formed to have the same circuit configuration and characteristics as the input circuit section 11. Both feedback circuit sections 12a and 12b are connected to the input circuit section 11, respectively, and the output signals in phase with each other. and to obtain the V _{ou t1,} V _out2. As a result, since only one input circuit section 11 is provided for the output signals V _out1 and V _out2 , an increase in the number of elements constituting the amplifier circuit 10 can be suppressed.

Since the feedback circuits 12a and 12b are formed to have the same circuit configuration and the same characteristics, the output signals V _out1 and V _out
The amplification factor of _out2 can be made the same, and the relative accuracy of the output signal can be improved. On the other hand, the feedback circuit 12
a, even variation occurs in the gain of the 12b, since the input circuit section 11 to the output signal V _out1, V _out2 is common, to reduce the difference in gain of the output signal V _out1, V _out2 Therefore, the relative accuracy can be improved as compared with the conventional amplifier circuit 43.

The present invention is not limited to the above embodiment. For example, in the above embodiment, the output signal V having the same phase is used.
_out1, V _out2 feedback circuit portion 12a to the input circuit section 11 so as to obtain, but connects 12b, as shown in FIGS. 4 and 5, the output signal V _out3 is opposite phases with respect to the output signal V _out1 As described above, the present invention may be implemented in the amplifier circuit 20 to which the feedback circuit unit 12b is connected. The connection will be described in detail. The current I _O1 output from the input circuit section 11 is input to the emitter of the PNP transistor Tr23 opposite to the above-described embodiment, and the current I _O2 is similarly input to the PNP transistor opposite to the above-described embodiment.
The signal is input to the emitter of the transistor Tr21.

In this amplifier circuit 20, the output signal V
_{Assuming that} the fluctuation amount of _out3 is ΔV _out3 , the input signals V _in1 , V
_The variation ΔV _out3 of the _in2 with respect to the potential difference ΔV _in is ΔV _out3 = −ΔV _in · (R1 / R2) · (1 + R23 · (R21 + R22) / (R21 · R22)) ────────── (33) ).

Here, the feedback circuit section 12a and the feedback circuit section 1
2b has the same configuration and characteristics. Therefore, from Expressions (30) and (33), ΔV _out1 = −ΔV _out3 ────────── (34), and the output signals V having the same amplification factor and mutually opposite phases are obtained.
_out1 and _Vout3 can be obtained. Also in this case, the input circuit unit 11 is common even if the amplification factors of the feedback circuit units 12a and 12b vary as in the above-described embodiment.
The relative accuracy of the output signals V _out1 and V _out3 can be improved as compared with the related art.

Further, the number of feedback circuit units connected to the input circuit unit 11 may be changed as appropriate. At this time, all the other output signal of the output signal output from the amplification circuit 10 to the output signal V _{ou t1} may also be connected to the same phase. Also, the connection may be made such that all the other output signals have the opposite phase to the output signal V _out1 . Furthermore,
The amplification circuit 10 may be formed by arbitrarily setting the ratio of the output signal having the same phase and the output signal having the opposite phase.

[0058]

As described in detail above, according to the present invention,
It is possible to reduce the size of the device itself by suppressing an increase in the number of constituent elements, and to provide an excellent effect that the relative accuracy of a plurality of outputs can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is a block circuit diagram showing an amplifier circuit configured for an in-phase output according to one embodiment of the present invention.

FIG. 3 is a circuit diagram illustrating an amplifier circuit configured for an in-phase output according to one embodiment.

FIG. 4 is a block circuit diagram showing another example of an amplifier circuit configured to have an inverted-phase output.

FIG. 5 is a circuit diagram illustrating another example of an amplifier circuit configured to have an inverted-phase output.

FIG. 6 is a block circuit diagram illustrating a conventional amplifier circuit.

FIG. 7 is a block circuit diagram of a conventional in-phase output amplifier circuit.

FIG. 8 is a block circuit diagram of a conventional anti-phase output amplifier circuit.

[Explanation of symbols]

1 input circuit section 2 feedback circuit portion I _O1 output current I _O2 output current OP1 operational amplifier circuit R1 and the resistor R2 resistors R11 R12 resistor R13 resistor Tr3 NPN transistor Tr6 NPN transistor Tr11 PNP transistor Tr12 NPN transistor Tr 13 PNP transistor Tr14 NPN transistor V _in1 input Signal _Vin2 input signal _Vout1 output signal _Vref1 reference voltage _Vref2 voltage

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Yoshihiro Suzumura 2-1844-2 Kozoji-cho, Kasugai-shi, Aichi Fujitsu VSI Co., Ltd. (56) References JP-A-2-257709 (JP, A) (58) Field surveyed (Int.Cl. ⁷ , DB name) H03F 1/00-3/72

Claims (2)

(57) [Claims] 1. The collectors of a pair of first and second NPN transistors (Tr3, Tr6) driven by a constant current are connected to each other via a first resistor (R1).
And an emitter of the second NPN transistor (Tr3, Tr6) via a second resistor (R2) connected to each other, the emitter to the input signal of the first and second NPN transistors (Tr3, Tr6) (V _in1 , V _in2 ), and inputs the first
An input circuit section (1) for outputting output currents (I _O1 , I _O2 ) from both terminals of a resistor (R1) of the first circuit and a pair of first and second PNP transistors (Tr11, T11).
r13) are connected to the output currents (I _O1 ,
I _O2 ), and the collectors of the first and second PNP transistors (Tr11, Tr13) are connected to the collectors of a pair of third and fourth NPN transistors (Tr12, Tr14) constituting a current mirror circuit, respectively. A reference voltage (V _ref1 ) is input to the base of the first PNP transistor (Tr11), and an operational amplifier circuit (OP1) is connected to the collector of the first PNP transistor (Tr11).
To output an output signal (V _out1 ) from the operational amplifier circuit (OP1), and output the output signal (V _out1 ).
It is connected between said reference voltage (V _ref1)
Third and fifth resistors (R11, R13) whose connection points are connected to the base of the second PNP transistor (Tr13 ).
And a fourth resistor connected between the connection point and the ground.
An amplifier circuit comprising a feedback circuit section (2) provided with a resistance (R12) , wherein a plurality of feedback circuit sections (2) are provided for the input circuit section (1), and each feedback circuit section (2) is provided. The first and second
PNP transistor (Tr11, Tr 13) of the amplifier circuit, characterized in that so as to respectively input the output current (I _O1, I _O2) of the input circuit section to the emitter (1) of. 2. The amplifier circuit according to claim 1, wherein a plurality of feedback circuit sections are provided for the input circuit section, and at least one of the feedback circuit sections is provided. Regarding (2), the input currents (I _O1 , I _O2 ) input to the emitters of the first and second PNP transistors (Tr 11, Tr 13) are opposite to those of the other feedback circuit (2). An amplifier circuit connected to the circuit section (1).