SU1739476A1 - Current amplifier - Google Patents

Abstract

This invention relates to a measurement technique. The purpose of the invention is to reduce power consumption. The goal is achieved by reducing the currents of current-generating elements made on current reflectors, тока 3 times. To increase the overload capacity of the input stage, two transistors and a bias resistor are introduced into the current amplifier. 1 il.

Description

The invention relates to measurement technology, automation and can be used in linear current amplification devices.

The purpose of the invention is to reduce power consumption.

The drawing shows an electrical circuit diagram of a current amplifier.

The current amplifier contains the first-tenth transistors 1-10, the first and second current reflectors on transistors 11-18. on the current supply element 19, the bias resistor 20, the power bus 21 and 22, and the common bus 23.

The current amplifier operates as follows.

When the power is turned on, cell 19 and transistors 5 and 6 receive a bias current UCM equal to

cm

 Tspit + Zgsht - (Zbe11 + Zbeb) + U & 312)

R19

where ipit +, Unm is the voltage on the power supply buses 21 and 22, respectively;

11e1,11b5, kbeb, U6312- base-emitter voltage of transistors 11, 5, 6 and 12, respectively;

Rig - the value of the resistor element 19.

Through the current sensor of the first and second current reflectors on the transistors 11 and 12, connected according to the diode circuit, the base current of the transistors 5 and 6 flows, respectively, i.e.

SP

with

1n

 cm

F

AND 2

Ic

w

where In, 112 is the current through transistors 11 and 12, respectively;

/ fe. - current gain (3 transistors 5 and 6, respectively.

The current amplifier must be implemented on pairs of transistors, made in the integrated design. This allows the reflection coefficient of all current reflectors to be practically equal to one. Consequently, a current of 1 cm // 5 and 1 cm // 3e, respectively, flows from the first, second and third outputs of the first and second current reflectors.

N

GO Yu VI | 0s

Through transistors 7 and 8, which are sensors of current reflectors implemented on transistors 1 and 2 of the input stage, current will flow

2 I

cm

W

and 8

2 1CM W

Through the input transistors 1 and 2 will flow the average current of the transistors 7 and 8, i.e.

AND 2

I7 + i8

Ј +

The base current of transistors 3 and 4 is equal to the algebraic sum of currents of transistors 15, 1 and 18, 2, respectively, i.e.

..ICM,,, I cm

1b-15-11.2 JЈ-l ™ ($ + - $ - fa. .ICM | / I i 1 h cm

.2-118 TE - «(Ј + $) 1bz, 1b4 - base current of transistors 3 and 4, respectively;

h, 2 - the average current through the transistors 1 and 2;

115, ITS is the current of the first outputs of the first and second current reflectors.

Then the currents through the transistors 3 and 4 will be respectively equal

1z 1bz Ts / J6

R

Taking into account that, a f $ 4, as transistors of the same conductivity in the integral performance, we get

Taking into account that the circuit is symmetrical with respect to the common bus 23 of zero potential, we consider the operation of only one half of the circuit, for example, the lower one, with a flowing input current. In this case, the input stage on the transistor 2, connected according to the common base circuit, creates a current gain equal to CKI. The amplifier stage on the transistor 4, connected according to the circuit with a common emitter, creates a current gain equal to

The operation of the second half of the device is similar to that considered, only with opposite increments.

The current gain of the device is

K1. ffl & + ffl & .g

wed

0

five

0

five

0

five

0

five

0

five

where "1, ar are the current gains of the circuits with the common base of the respective transistors;

Dz. current gains of transistors 3 and 4, respectively;

/ Zsr is the arithmetic average of the coefficients of the pnp and npn transistors.

Thus, the current amplifier can operate in a DC amplifier mode by reducing the influence of the spread on the / 3 transistors 3 and 4.

Claims (1)

Invention Formula The current amplifier containing the first and second transistors having a different structure, the emitters of which are connected and are the input of the current amplifier, the third and fourth transistors connected according to a common emitter circuit, the collectors of which are the output of the current amplifier, the bases are connected to the collectors of the first and The second transistors and the outputs, respectively, of the first and second current reflectors, the inputs of which are connected to the bases of the fifth and sixth transistors, respectively, whose collectors are connected to the corresponding buses power supply, the seventh and eighth transistors, the emitters of which are connected to a common bus, and the bases are connected to the bases of the first and second transistors, as well as the current supply element, while the structure of the fourth, fifth and seventh transistors corresponds to the structure of the first transistor, and The sixth, eighth transistor corresponds to the structure of the second transistor, characterized in that. In order to reduce power consumption, the first and second current reflectors are each made with the first and second additional outputs, and a bias resistor is introduced, the ninth and tenth transistors having the structure of the first and second transistors and the emitters of which are connected to the bases of the seventh and the eighth transistor and the bias resistor pins, while the base of the ninth transistor is connected to the collector of the seventh transistor and the first and second additional outputs of the first current reflector, and the base is The EU transistor is connected to the collector of the eighth transistor and the first and second additional outputs of the second reflector, the collectors of the ninth and ten transistors are connected to emitters with the third and fourth transients are between the emitters of the fifth and sixth transistors, and the current supply element is switched on.