JPS63276307A - Amplifier circuit - Google Patents

Abstract

PURPOSE:To prevent the deterioration in the AC characteristic and the production of an error by adopting a common emitter or common source connection to a complementary transistor (TR) to an emitter or source of a TR of common base or common gate connection so as to decrease number of components and reduce the power current. CONSTITUTION:Differential pair TRs 17, 18 driven by a current source 7 amplify the signal given from input terminals 3, 4 together with active loads 5, 6 and the amplified output is given to an emitter of a TR 10 and a base of a TR 11 via an emitter follower comprising a TR 8. A common base input resistance R1 is expressed in equation I, where alpha10 is a common base current amplification factor of the TR 10 and gm10 is the mutual conductance. Then equation II is established, where gm11 is the mutual conductance of a TR 11 itself and Gm is the overall mutual conductance of the resistor Ri and the TR 11. Then equation III is established, and equation V is given under the assumption of the establishment of equation IV, and the mutual conductance is a half the conventional circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an amplifier circuit, and more particularly to an amplifier circuit having a single input and two types of outputs, a sink and a source.

[Conventional technology]

Conventionally, this type of amplifier circuit, as shown in FIG.
One collector of the multi-collector transistor 14 was used as the source output 13, and the other collector was turned back by a current mirror circuit composed of transistors 15 and 16 to generate the sink output 12.

[Problem that the invention seeks to solve]

The above-mentioned conventional amplifier circuit generates a folded output using a current mirror circuit, etc., which increases the number of elements, which has the disadvantage of increasing power supply current, deteriorating AC characteristics, and generating errors. .

In particular, when an error occurs, an additional circuit element for error compensation is required, and in terms of AC characteristics, the difference in the frequency characteristics and phase characteristics of the two outputs is a significant constraint in circuit design.

[Means for solving problems]

The amplifier circuit of the present invention includes a first transistor whose base or gate is grounded, and a second transistor which is complementary to the first transistor and whose emitter or source is connected to the emitter or source of the first transistor. and is configured to input a signal to the base or gate of the second transistor and output the signal from the collector or drain of the first and second transistors.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a circuit diagram of an embodiment of the present invention.

1 is a power supply terminal, and 2 is a terminal with the lowest potential. Differential pair transistors 17 and 18 driven by current source 7 amplify the signal input from input terminal 3.4 together with active loads 5 and 6, and the amplified output is passed through the emitter follower of transistor 8 and then connected to the base. grounded transistor 10
and the base of the transistor 11 whose emitter is grounded, and the output is branched here.

Here, the transistor 11 has a grounded emitter with the grounded base input resistance Ri of the transistor 10 serving as an emitter generation resistance.

If the common base current amplification factor of the transistor 10 is α10° and the mutual conductance is g m IQ, then Ri =
a 10 / g m 1o --(1), so the mutual conductance of transistor 11 alone is gml
t, and the total mutual conductance of the emitter generation resistor Ri and the transistor 11 is Gm, then Gm'=gm+t/ (1st gm llRi
) −・”t2). Therefore, G m ′ g m 11/ (1± gml
l α to/ g m to)・・・・・・(
3) becomes (210= l, g m 10= g
Assuming m 11, G m = g m t 1/2 -- G41, and a transconductance that is about half of that in a conventional amplifier is obtained.

Although the embodiment shown in FIG. 1 is composed of bipolar transistors, the same effect described below can be obtained even if the transistors 10 and 11 are replaced with two mutually complementary field effect transistors.

〔Effect of the invention〕

As explained above, according to the present invention, by grounding the emitter (or source) of a complementary transistor to the emitter (or source) of a transistor whose base is grounded (or gate grounded), the number of elements is small. Accordingly, the power supply current is small, and there is an effect that it is possible to easily realize an amplifier circuit that can obtain two types of good outputs, sink and source, with little difference in AC characteristics and little error.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIG. 2 is a circuit diagram showing an example of a conventional amplifier circuit. 1... Power supply terminal, 2... Lowest potential terminal, 3, 4...
・Input terminal, 5, 6...active load, 7...current source,
8... Emitter follower transistor, 9... Resistor,
10...Transistor, 11...Transistor, 1
2.13 Ishimo 1 Sekimo 215! J

Claims (1)

[Claims] a first transistor whose base or gate is grounded;
The first transistor has a complementary second transistor whose emitter or source is connected to the emitter or source of the first transistor.
Input a signal to the base or gate of the transistor,
An amplifier circuit characterized in that a signal is output from the collectors or drains of the first and second transistors.