SU1381686A1 - Differential amplifier - Google Patents

Abstract

The invention of m. used in operations. yhl. The purpose of the invention is to increase the stability of the coefficients. gain and increase coefficients. common mode suppression. The cell contains four transistors (T) 1-4, three grs 5-7 currents, four resistors 8-11, a bias voltage source 12, and power supply buses 15 and 16. Mr. 5 is made on T 13, diode 14. Because of the presence of resistors 8-11, a high degree of stabilization is achieved. gain The increase in collector currents T 1,2 leads to a decrease in the same value of currents of emitters T 3 and 4, because the total values of collector and emitter currents T 1.3 and 2.4 are stabilized by g-rms 6 and 7. A decrease in the currents of emitters T 3 and 4 leads to a decrease in their collector currents and, consequently, to a decrease in the collector current T 13 and an increase in the coefficient common mode suppression. 1 il. (L

Description

00 OS

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This invention relates to radio engineering and can be used in operational amplifiers.

The purpose of the invention is to increase the stability of the gain and increase the common mode rejection ratio.

The drawing shows a circuit diagram of a differential amplifier.

The differential amplifier contains the first - fourth transistors 1-4, the first - the third current generators 5-7, the first - the fourth resistors 8-11, the bias voltage source 12, the first current generator 5 being made on a transistor 13, a diode 14, and also the first and second power supply tires 15.16.

Differential amplifier works as follows.

The paraphase signal supplied to the inputs of the differential amplifier is amplified by transistors 1.2 and is allocated to their collector loads consisting of resistors 8.9, current generators 6.7 and transistors 3.4. Under the influence of destabilizing factors, such as temporary aging, temperature and process instability, the parameters of both transistors 1, 2 and transistors 3,4 change. At the same time, the presence of the first to fourth resistors 8-11 causes a simultaneous change in the parameters of transistors 1-4 to cause an opposite change in the gain of the differential amplifier, for example, if a decrease in the transfer coefficient of the base current of transistors 1.2 leads to a decrease in the gain, This. simultaneous reduction of the base current transfer coefficient of the transistors 3.4 results from the introduction of the third and fourth resistors 10.11 to an increase in the resistance of the transistors .3.4 with s emitter, and hence to increase the gain. The presence of the first and second resistors 8.9 makes it possible to optimize the process of compensating for the gain instabilities. Thus, due to the presence of resistors 8-11, a high degree of stabilization of the gain factor is achieved.

Combining the collectors of transistors 3, 4 and connecting them to the base of transistor 13 of current generator 5 and simultaneously through (directly shifted) diode 14 to the first power supply line 13 causes the common mode to enter 1.2 in-phase signal at the input of transistor

0 of the current generator 5, made on the transistor 13, the collector currents of the transistors 1.2 begin to change, for example, to increase. Increased collector current transistors

5 1.2 will lead to the fact that the emitter currents of transistors are 3.4 by 3.4, because the total values of collector and emitter currents of transistors are 1.3 and 2.4

0 stabilized by 6.7 current generators respectively. In turn, a decrease in the emitter currents of the transistors 3, 4 leads to a decrease in their collector currents, and the investigator5 also reduces the collector current of the transistor 13 and increases the common-mode suppression factor.

Claims (1)

0 Formula from Bren A differential amplifier containing the first and second transistors having the same structure, the emitters of which are combined and connected to the first power supply bus through the first current generator, and the bases are the corresponding inputs of the differential amplifier, the third 0 and the fourth transistors connected by cxt; Me with a common base, having a different structure, the emitters of which are connected to the second through the second and third current generators respectively 5 bus power supply, and through the first and second resistors to the collectors of the first and second transistors, as well as the source of the bias voltage, characterized in that Q what, with: the purpose of increasing the stability of the gain factor and increasing the suppression factor of the common mode signal, the first current generator is controlled, to the control input of which the collectors of the third and fourth transistors are connected, the bases of which are connected to the output of the source through respectively 313816864 the bias voltages, and the collectors are the corresponding outputs of the differential first and second transistors - a power amplifier.