RU1776U1 - EMITTER REPEATER ON COMPLETE TRANSISTORS - Google Patents

Abstract

EMITTER REPEATER ON COMPLETE TRANSISTORS, the emitters of which are connected and connected to the output of the repeater, and the collectors are respectively to the positive and negative terminals of the power supply, the first and second resistors of the base divider are connected between the collector and the base of the first and second transistor, characterized in that the base of the transistors interconnected using a third resistor, and with the input of the repeater - using the first and second capacitor.

Description

Emitter follower on complementary transistors.

The alleged invention relates to the field of semiconductor amplification technology, in particular, to emitter followers.

The main purpose of emitter followers is to amplify the signal power without increasing the voltage amplitude. Figure 1 shows a diagram of the most common emitter follower with a typical load in the form of parallel connected resistor K4 and capacitor C4. The disadvantage of this device is the uneven transmission of the positive and negative. Fronts of the pulse signal: for pnp transistors, the negative front is transmitted worse than the positive one / I.P. Stepanenko Fundamentals of the theory of transistors and transistor circuits, ed. Energia, Moscow, 1973, pp. .368, Fig. 9-6 /.

The reason for this negative phenomenon is that: during the positive edge of the signal, the capacitor C3 is charged through the relatively small output resistance of the opening transistor T1, and during the negative, it is discharged through the internal resistance of the underground transistor and parallel connected resistors EZ and K4, which are on. one or two more order.

A slight improvement in the development of the negative front is possible due to a decrease in the resistance of the EZ resistor, however, the power dissipated by the transistor yT1 increases, which adversely affects the reliability and efficiency of the equipment as a whole.

A radical solution to this problem is to build an emitter follower on complementary transistors, i.e. p-p-p and p-p-p-type / A.G. Alekseev and G.V. Voishvillo Operational amplifiers and their application Ser. Mass radio library, production of fine arts. M .: Radio and communications, 1989, p. 91, fig. 9.35 / - (prototype

Schematic diagram of the emitter follower prototype shown in figure 2. The emitter follower consists of two series-connected transistors VTI (npn type) and VT2 (pnp type), the emitters of which are connected and connected to the output of the emitter follower, and the collectors, respectively, to the positive and negative terminals of the power supply and the base divider voltage, consisting of series-connected resistor RI, diodes VD1, VD2 and resistor E2, while the base VT1 is connected to the connection point of the resistor R1 and the anode VDI g base VT2 is connected to the connection point of the resistor R2 and cathode 2, and cathode 1 and anode VD2, united in They are connected to the input of the emitter follower.

The emitter repeater operates as follows. When you turn on the supply voltage between the anode VDI method 2, a potential difference is formed, sufficient for a preliminary small erase of both transistors. The positive half-wave of the input sinusoidal signal or the positive feedback of the pulse is transmitted to the base VT1 through a small dynamic resistance of the diode VD1 and increases the conductivity of the VTI, while the conductivity of the VT2 decreases, so all the current flowing through VTi goes to the load. A similar process occurs when -; ..

let go of the output of the negative half-wave and the negative frint sEgkala. In this case, the entire load current flows through the trans

ZISTOR VT2.

As authors A.G. Alekseev and G.V. Boyshvrshlo write on p. 92 of the book Operational amplifiers and their application, the most suitable for this device are diodes 223, and the divider current in the absence of a signal is, When the voltage of the power supply is plus and Menus 15 2 emitter followers can work out the input signal input circuit of not more than 10 V, At large amplitudes, obviously, nonlinear distortions occur.

From the data presented by the authors, it can be seen that the linear dynamic range of the prototype repeater does not exceed 66 E, while the current through the auxiliary circuit, the basic divider, in the absence of a signal is 5-10 times higher than the current through the main circuit, i.e. transistors VTi and VT2,

The reason for these shortcomings is the use of VDI and VD2 diodes for preliminary wiping off of VTi and VT2 transistors and, as a result, it is necessary to transmit the input signal to VTI bases and through the dynamic resistance of these diodes. / When bypassing the diodes, the output characteristic of the prototype repeater acquires a pronounced dead band /.

The technical task of the proposed invention is to increase the linear dynamic range, save energy and reduce the cost of the device.

The problem is solved in that in the emitter follower on complementary transistors, the emitters of which are connected and connected to the output of the emitter follower, and the collectors, respectively, to the positive and negative terminals of the power supply, and the first and second resistors of the base divider are connected respectively to the collector mead and base of the first and collector and base

of the second transistor, a third resistor is introduced between the bases of both transistors and two capacitors, one of which is connected

to the input of the emitter follower, and the other to the corresponding base of the first and second transistor.

Schematic diagram of the proposed emitter follower shown in Fig.Z. The emitter follower consists of two transistors UT1 pnp-type and ut2 pnp-type, the emitters of which are connected and connected to the output of the repeater, and the collectors

from

respectively, to the positive and negative terminals of the power supply Up of the base voltage divider of three resistors, of which the first RI and second R2 are connected between the collector and the base of the corresponding transistor, and the third R3 is the mead with the bases of the transistors, and two capacitors 01 and 02, one of which connected to the input of the repeater, and the second to the base of the corresponding transistor VTlH VT2.

The proposed emitter follower works as follows: When the supply voltage is turned on, a potential difference appears on resistor R3, which is necessary for preliminary unlocking of both transistors VT1 and VT2.The signal arriving at the input of the repeater through capacitors CI and C2 directly goes to the base of the transistors. In this case, for one of them, the signal is unlocking, and for the other it is locked. As a result, the entire current of the opening transistor is output to the load. When the polarity of the input signal changes, the entire load current passes through another transistor. In the case of a pulsed signal, both of its edges are processed equally, because The charge and discharge of the load capacitance and the mounting capacitance occurs first through one, and then through another opening transistor.

In the basic circuit of the proposed emitter follower there are no elements (diodes) that can exit the mode with low dynamic resistance with increasing signal amplitude, therefore the dynamic linear range for positive, for example, half-wave

is equal to:

UJJP's - UK9 15V - 0.5V 14.5V

j 0.96, i.e., 96, where Ujjjj is the dynamic range. IN;

fU is the voltage of the half-light source with bipolar

power supply or half the voltage of the source with unipolar power, V; tf9 - voltage across the collector and emitter of the transistor

VT1 at saturation, V;

 - the dynamic range in relative units, The combined use in the proposed repeater of the above-mentioned known and distinctive features will allow to obtain a new technical result, which consists in increasing the linear dynamic range, as well as the base circuit of the proposed emitter repeater consumes 50-100 times less current compared to the base prototype circuit, therefore, its total current consumption is at least 5 times less.

The proposed repeater is cheaper than the prototype repeater, because two capacitors and one resistor are less than two diodes.

The proposed emitter follower was manufactured in at least ten copies for amplifiers of both radio and I / O signals, as well as for audio frequency amplifiers.

The proposed repeater can be widely used in equipment for various purposes.

- m

Claims (1)

EMITTER REPEATER ON COMPLETE TRANSISTORS, the emitters of which are connected and connected to the output of the repeater, and the collectors are respectively to the positive and negative terminals of the power supply, the first and second resistors of the base divider are connected between the collector and the base of the first and second transistor, characterized in that the base of the transistors interconnected using a third resistor, and with the input of the repeater - using the first and second capacitor.