JPH0244405B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an amplifier circuit that makes it possible to extract an amplified output and a rectified output of a signal.

Conventionally, when a signal amplification system and a rectifier circuit that forms a control signal for level adjustment are installed together, such as an automatic level control circuit in the recording system of a tape recorder,
The amplifier circuit and rectifier circuit are configured separately. This has resulted in a disadvantage that the circuit configuration becomes complicated and the manufacturing cost increases. Another drawback was that it was difficult to control the amplified output and rectified output of the amplifier circuit, such as level control.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an amplifier circuit that can simultaneously amplify and rectify a signal using a common circuit.

That is, the amplifier circuit of the present invention includes first and second transistors 16 and 18 having a common emitter, a differential circuit 2 that amplifies an input signal applied to the base of the first transistor, and a constant current a constant current source 36 that generates a constant current, a first current inversion circuit ₆ that receives the constant current from the constant current source, generates a first current 1, and causes the first current to flow through the differential circuit; a second current inversion circuit 8 that takes out a second current ₂ flowing through the first transistor of the differential circuit; and a third current inverting circuit 8 that takes out a third current I ₃ that flows through the second transistor of the differential circuit. receives the second current from the second current inverting circuit 10 and the second current inverting circuit 10;
and the third current of the current inverting circuit,
Fourth current inversion circuit 12 that takes out an output current of ₀
and receives a fourth current ₀₂ corresponding to the constant current from the first current inversion circuit, and receives a fifth current ₀₁ corresponding to the second current from the second current inversion circuit. A current combining circuit 14 that combines both of them and takes out the sixth current ₀₃ , and a rectifier 62 that rectifies the sixth current obtained by this current combining circuit are installed on the base input side, and The circuit includes a third transistor 68 which receives the current at its base, and a rectifier circuit 4 which takes out a rectified output of the sixth current.

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings.

FIG. 1 shows an embodiment of the amplifier circuit of the present invention. This amplifier circuit includes a differential amplifier equipped with a differential circuit 2, and a rectifier circuit 4 installed on the subsequent stage side.
The differential circuit 2 is supplied with an operating current by the first current 1 through the first current inverting circuit ₆ , and its amplified output is supplied to the second current inverting circuit 8, the third current inverting circuit 10, and the fourth current inverting circuit 10. The constant current taken out by the current inverting circuit 12 and flowing through the current inverting circuit 6 and the output current of the current inverting circuit 8 are combined in the current combining circuit 14, and then rectified by the rectifier circuit 4, and the rectified output is is extracted separately from the amplified output.

The differential circuit 2 has a first and a second circuit that share a common emitter.
An input signal to be amplified is applied to the base of the transistor 16 through an input terminal 20, and a constant DC bias input applied to a bias input terminal 24 is applied through a resistor 22. Further, a feedback circuit 26 is formed between the base of the transistor 18 and the output side, that is, a resistor 28 is connected between the base of the transistor 18 and the output point, and a resistor 30 is connected to the base of the transistor 18. A bias input terminal 32 is formed through the bias input terminal 32, and a constant bias input is applied to this bias input terminal 32.

Further, between the emitters of the transistors 16 and 18 and the reference potential line on which the reference potential terminal 34 is formed, a transistor 38 of a constant current circuit 6 which supplies an operating current to each transistor 16 and 18 from a constant current source 36 has an emitter. is connected to the reference potential line side. The base and collector of a transistor 40 are commonly connected to the base of this transistor 38, and a constant current source 36 is connected between the base collector of the transistor 40 and a power line to which a drive voltage Vcc is applied from a power supply terminal 42. connected,
The emitter of transistor 40 is connected to a reference potential line.

The amplified output of the differential circuit 2 is the transistor 16,1
The current is taken out from the collector side of 8 by current inverting circuits 8 and 10. That is, between the collectors of the transistors 16 and 18 and the power supply line, transistors 44 and 46, which have a common base and collector and are configured as diodes, are individually connected with their emitters facing the power supply line. The base of a transistor 48 is connected to the base and collector of the transistor 46, the base of a transistor 50 is connected to the base and collector of the transistor 44, the emitters of each transistor 48 and 50 are commonly connected to a power supply line, and each transistor A transistor 5 is connected between the collectors of 48 and 50 and the reference potential line.
2 and 54 are connected with their emitters facing the reference potential line. The base and collector of transistor 52 and the base of transistor 54 are connected in common, and an output terminal 56 is formed at the collectors of transistors 50 and 54.

The current combining circuit 14 includes a transistor 58 whose base is shared with the base and collector of the transistor 40, and the transistor 44.
A transistor 60 having a common base and collector is connected in series between a power supply line and a reference line, with the collector being common.

The output of this current combining circuit 14 is the transistor 5
8 and 30, and a rectifier 62 is connected between this collector and the reference potential line.
and a resistor 64 are connected. The rectifier 62 is composed of a diode, and since it is composed of a semiconductor integrated circuit in this embodiment, it is composed of a transistor 66 having a common base and collector.
The base and collector of this transistor 66 are
The base of transistor 68 is connected, the collector of transistor 68 is connected to a power supply line, and an output terminal 70 is formed at its emitter. A resistor 72 and a capacitor 74 are connected in parallel between the output terminal 70 and the reference potential line, forming a smoothing circuit that converts the rectified output into DC.

The operation will be explained based on the above configuration. The input signal voltage applied to the input terminal 20 is V _IN , its fluctuation component is ΔV _IN , the first current flowing as an operating current to the differential circuit 2 through the transistor 38 _{is 1} , and the second current flowing to each transistor 16 and 18 is ΔV IN . Assuming that the current is ₂ , the third current is ₃ , and the constant current flowing through the constant current source 36 is ₄ , an output current of ₀ flows through the transistor 50 due to the fluctuation component ΔV _IN .

That is, V _OUT, which is an amplified output of the input signal voltage, can be taken out from this output terminal 56.

Assuming that the fifth current flowing through the transistor 60 in relation to the current inverting circuit 8 _{is 01} , and the fourth current flowing in the transistor 58 in relation to the constant current circuit 6 is ₀₂ , the current combining circuit 14 combines the two. A sixth current ₀₃ flows through the rectifier 62 as the combined current. That is, as a result of this rectification, V _ODET is taken out at the output terminal 70. Therefore, if the resistance value of the resistor 72 is R, then this
V _ODET is given by V _ODET = R· ₀₃ (1), where current ₀₃ is given by the following equation. That is, ₀₃ = ₀₁ + Δ ₀₁ − ₀₂ = ₂ + Δ ₂ − ₀₂ = ₁ / 2 + Δ ₂ − ₀₂ = ₄ + Δ ₂ − ₄ = Δ ₂ ...(2) In equation (2), Δ ₂ is the signal voltage V _IN The fluctuation component of is given by ΔV _IN . Therefore, V _ODET shown in equation (1) becomes as shown in the following equation. That is, V _ODET =R·Δ ₂ (3), and this output is obtained at the output terminal 56.

According to such an amplifier circuit, it is possible to extract the signal component which is the normal amplified output from the differential amplifier on the front stage side, and also to rectify the amplified output obtained in this amplification operation and take it out from the output terminal 70. can. That is, one set of circuits can have both an amplification function and a rectification function and can selectively take out the functions, or it is also possible to use both at the same time. Therefore, the circuit configuration is simplified and manufacturing costs can be reduced.

Further, by controlling the operation of the constant current source 36 using the constant current ₄ , output extraction can be controlled.

FIG. 2 shows another embodiment of the amplifier circuit of the present invention, in which a resistor 76 is inserted on the emitter side of the transistor 60. By adjusting this resistance value or the value of the constant current source 36, the value of the output voltage can be adjusted.

As described above, according to the present invention, the amplified output of the signal voltage and the rectified output thereof can be output simultaneously or selectively, and the circuit configuration can be simplified and the manufacturing cost can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the amplifier circuit of the invention, and FIG. 2 is a circuit diagram showing another embodiment of the amplifier circuit of the invention. 2... Differential circuit, 4... Rectifier circuit, 6... First current inversion circuit, 8... Second current inversion circuit, 10... Third
current inversion circuit, 12... fourth current inversion circuit, 1
4... Current combining circuit, 16... First transistor,
18... Second transistor, 36... Constant current source, 6
2... Rectifier, 68... Third transistor, ₁ ...
First current, ₂ ...Second current, ₃ ...Third current, ₄ ...Constant current, ₀₁ ...Fifth current, ₀₂ ...Fourth current
current, ₀₃ ...sixth current.

Claims (1)

[Claims] 1. A differential circuit configured with first and second transistors having a common emitter and amplifying an input signal applied to the base of the first transistor, and a constant current source generating a constant current. a first current inversion circuit that receives the constant current from the constant current source, generates a first current, and causes the first current to flow through the differential circuit; a second current inversion circuit that takes out a second current flowing through the transistor; a third current inversion circuit that takes out a third current flowing in the second transistor of the differential circuit; and the second current inversion circuit. a fourth current inversion circuit that receives the second current from the circuit, combines the second current with the third current of the third current inversion circuit, and extracts an output current; A fourth current corresponding to the constant current is received from the inverting circuit, and a fifth current corresponding to the second current is received from the second current inverting circuit and both are combined to generate a sixth current. A current combining circuit for taking out a current, and a third transistor having a rectifier for rectifying the sixth current obtained by the current combining circuit on the base input side and receiving the sixth current at the base, and a third transistor for receiving the sixth current at the base. 6. An amplifier circuit characterized by comprising: a rectifier circuit that takes out a rectified output of the current of 6;