JPS58213510A - Amplifying circuit - Google Patents

Abstract

PURPOSE:To obtain a low distortion amplifying circuit having no negative feedback of an open loop by composing an input circuit of an emitter earthing type amplification transistor (TR) having emittor resistance, coupling a load to the input circuit through a current mirror and connecting a resistor having a resistance value (n) times the emitter resistance in series to (n) forward diodes. CONSTITUTION:An input terminal 1 is connected to the base of an npn amplification transistor TR1 having high hFE, the emitter of the TR1 is earthed through an emitter resistor R1 and the collector of the TR1 is connected to the collector of a pnp TR2 which is one component of the current mirror. Although the collector of a TR3 has the same characteristics as that of the TR1, the collector is earthed through series connection consisting of (n) TR4-TRn+3 each of which is short-circuited between its collector and base and a resistor R2. The voltage taken out from an output terminal 3 is (n) times the voltage applied to the input terminal 1. Namely, the circuit shown in figure is an (n) times amplifier.

Description

[Detailed description of the invention] The present invention relates to an amplifier circuit using transistors.

It was customary to apply negative feedback in the loop. Although this method certainly has advantages, it has been pointed out that it has drawbacks such as instability in the high frequency range, especially in audio 77p.

It is therefore an object of the invention to provide a low distortion amplifier circuit without open loose negative feedback.

In order to achieve the above object, an amplifier circuit according to the present invention includes:
The input circuit is a common emitter type amplification transistor having an emitter resistor, and the load is coupled to the input circuit via a current mirror, and the resistor has a resistance value n times that of the emitter resistor, and the n number of diagonal directions. The idea is to connect diodes in series.

In an advantageous embodiment of the invention, the forward diode is the same base-collector short-connected transistor as the amplification transistor. The above-mentioned vine resistance may be zero. In this case, the present invention will be explained in more detail with reference to the accompanying drawings below in series with the above-mentioned diode, but these are merely illustrative and there are various connections without going beyond the scope of the present invention. Of course, significant improvements and modifications are possible.

FIG. 1 is a circuit diagram of an amplifier circuit according to the present invention.

Input terminal l has high hF! c', the emitter of the transistor Trl is grounded through an emitter resistance ratio of 1, and the collector of the pnp transistor Tr2 forms a current mirror. It is connected to the. Transistor T r 2 base and current
The other pnp transistor T forming the mirror
The paces of r3 are both connected to the collectors of transistors Tr2 and their transistors Tr2 and T
Both emitters of r3 are supplied with current from Il'c power supply terminal 2. The collector of the transistor Tr3 has the same characteristics as the transistor Tr1.
n short-connected transistors Tr4. ...
It is grounded through the series connection of TrH+3 and resistor R2. The output is taken out from the output terminal 3 connected to the collector of the transistor Tr3.

The circuit shown in FIG. 1 operates as follows. Transistor Tr2 and transistor Tr3 have the same characteristics,
The currents flowing through them respectively] and 1' are equal in phase.

Ichiriki, Trl and Tr4. ...Tr n+3 also has the same characteristics, so their base-emitter voltage ■Bll w ■BF! 4 * “” BF! y
l+3 is the same 0 If this is written as VBK, the voltage vxn applied to input terminal 1 and the voltage appearing at output terminal 3 are ■. The relationship between is expressed as follows.

VIN=VBIC+R1x 1=-(1)■
o -nVBB + R2X I'... (2) I
= 1', so equation (2) can be written as Vo = nVBll, -1-R2I ・-(25. If 1 is deleted from equation (1) and both equations, it becomes. Here, in R2-nR1 If so, equation (3) becomes V(, = n
VBll++ n (VIN'VBE)"'nV
zn - (4), and the voltage appearing at the output terminal 3 is n times the voltage applied to the input terminal 1. That is, the circuit shown in FIG. 1 represents an n-fold increaser.

As is clear from the above explanation, the eminter resistor 1 may be zero. At this time, of course, the resistance ratio 2 is also zero.

As explained above, according to the present invention, a low distortion amplifier circuit can be realized in a highly integrated circuit without oven loop negative feedback, and a low distortion amplifier circuit with excellent stability in the high frequency range can be realized.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of an amplifier circuit according to the present invention. 1... Input terminal, 2... Power supply terminal, 3... Output terminal, Tr1# Tr41 ``'TI'n+3'''
npn) transistor, 'rr2゜Ill r3...
・pnp) transistor, 1. ■1.2...Resistance. Patent Applicant Clarion Co., Ltd. Agent Patent Attorney Nagai 1) Takeshi Part 3 Figure 1

Claims (3)

[Claims] (1) The input circuit is a common emitter type amplification transistor having an emitter resistor, and the load is a resistor having a resistance value n times the emitter resistor, which is coupled to the input circuit via a current mirror, and n number of resistors. An amplifier circuit characterized by a series connection of forward diodes. (2) The amplifier circuit according to claim 1, wherein the forward diode is the same base-collector short-connected transistor as the amplifier transistor. (3) The amplifier circuit according to claim 1, wherein the emitter resistance is zero.