SU1653129A1 - Composite transistor - Google Patents

Abstract

The invention relates to analog technology and may be used in integrated circuits containing amplifier stages. The purpose of the invention is to reduce the current flow, increase the current coefficient and decrease the input capacitance of the composite transistor. The composite transistor includes first and second transistors of the first conductivity type and third and fourth transistors of the second conductivity type. The introduction of new connections allows the use of the first transistor as a current amplifier, the base current of the first transistor is compensated by the current generated by the current transducer on the second transistor. The compensating current is transmitted to the base of the first transistor by means of a current reflector built on the third and fourth transistors. 1 il. (L

Description

The invention relates to an analog technique and can be used in integrated circuits containing amplifying K1SCEDA.

The purpose of the invention is to reduce the current consumption, increase the current gain and decrease the input capacitance of the composite transistor.

The drawing shows the electrical circuit of the proposed composite transistor.

The composite transistor contains the first transistor 1 of the first conductivity type, the emitter of which is the emitter 2 of the composite transistor, the second transistor 3 of the first conductivity type 3, the third and fourth transistors 4.5 of the second conductivity type, the emitters of which are connected and connected to the reference potential bus 6, the base 7 of the fourth transistor 5 and the base and collector of the third transistor 4. Are connected and connected to the base of the second transistor 3, the emitter of the second transistor 3 is connected to the collector of the first transistor 1, the collector of the second t the razistor 3 is the collector of the composite transistor, and the base of the first transistor 1 and the collector of the fourth transistor b are connected and are the base 8 of the compound transistor.

The invention consists in compensating the base current of the first transistor 1 used as a current amplifier by the current generated by the current converter. The second transistor 3 is used as a current transducer, which together with the first transistor 1 forms

O5

ate

with

Yo

turning on. The compensating current is transmitted to the base of the first transistor 1 by means of a current reflector built on the third and fourth transistor 4.5 o.

In order to clarify the invention, let us consider the operation of the proposed composite transistor in the switching circuit with a common emitter, where the emitter 2 is connected to the zero potential bus, and the collector is connected to the positive power bus Un through the load resistor 9. For normal operation of the proposed composite transistor, pa-coupled emitters 4 and 5 are fed with a positive reference pot Uon.

The magnitude of the reference potential must satisfy the relation

.

zi

Be

(t)

where U BE is the base-emitter transition voltage in forward bias (U gy 0, TB) .25 in order to ensure the linear operation of the transistor 1 used as a current amplifier.

As follows from the drawing, the linear mode of operation, in which the composite transistor amplifies the input signal, is provided by the magnitude of the base-bias voltage 8, equal to the value of the direct voltage across the emitter junction of the transistor. - At the same time, the transistor 1 operates as a current amplifier, in the base circuit of which the current Ig flows, in the collector circuit - 1К1, and Nm | i Npw I61, where I urn is the transistor gain factor of 1.3. Current 1K, flows through the transistor 3, which serves as a current transducer Ik4, to the base current of the transistor 3 16g-. In this case, the load current of the composite transistor is equal to the current of the collector of the transistor 3 and

 K2 KI

BGV turn, the base current of the transistor 50 1g serves as the input current of the current reflector, the output current of which I v compensates the base current of transistor 1.

Thus, the input current i & ig-i-- is equal to

.t

and the gain coefficient is

3 .. 1 I6 le, Since IKZ-IM - 162,

R.RN - P-,

4t

and Ijc - 1 $ g - 6t (with equal areas of emitter transitions of transistor 4 and 5) due to the practical identity of their operating modes, then fi 0МРМMore, a more rigorous analysis of the operation gives

PNPM

passion

R

i j. a Np NPN 1 PMW K () + T

where (Lrmp is the gain of transistor 4, 5; K 85/84, a 8 and 84 are the emitter junction areas of transistors 4 and 5, respectively. It should be noted that the proposed composite transistor, unlike the Darlington pair, allows using the corresponding coefficient K, realize an arbitrarily large coefficient / 3 regardless of specific values (iNpN, ft pup used, transistors.

Claims (1)

Invention Formula The composite transistor contains the first transistor of the first conductivity type, the emitter of which is the emitter of the composite transistor, the second transistor of the first conductivity type, the emitter of which is connected to the collector of the first transistor, the third transistor of the second conductivity type, whose base connected to the base of the second transistor and the fourth transistor of the second conductivity type, which differs by that, in order to reduce the current consumption, to increase the coefficient y ylene-current and reduce the input capacitance of the composite transistor, the fourth base and the collector of the third transistor connected to the third base, the emitters of the third and fourth transistors, either directly or through 51653129 The resistors connected to the reference bus are the base of the composite transistor potential, the base of the first and the collector. fourth transistors are combined and X