SU1388975A1 - Frequency converter - Google Patents

Abstract

The invention relates to radio engineering. The purpose of the invention is to expand the dynamic. range. The frequency converter contains differential. y-l, consisting of transistors (T) 1 and 2, source of current (IT) 3, resistors () 4 and 5, ring diode bridge, made on diodes 6-9, T 10 and P, P 12, 13, IT 14. IT 15 was introduced. There is no voltage overload in the converter, since The bridge diagonal, connected to the emitters T 10 and 11, is supplied with the same amplitude common-mode voltage. The junction points of the diodes are equipotential in the signal and the opening voltage on the open diodes is zero. Thus, the overload threshold of a device for voltage does not depend on the parameters of the diodes, but is determined by the operating mode of the amplifier stages on T 10 and II. 1 il. with SS

Description

(L

with

00 00

with SP

one

The invention relates to radio engineering and can be used in receiving devices.

The purpose of the invention is to expand the dynamic range.

The drawing shows a block diagram of the frequency converter.

The frequency converter contains a differential amplifier consisting of the first 1 and second 2 transistors, the first current source 3, the first 4 and second 5 resistors, a ring diode bridge made on four diodes 6-9, the third 10 and fourth 11 transistors, the third 12 and fourth 13 resistors, second

14 and third 15 current sources. Frequency converter running

in the following way.

Suppose that, on the basis of the first 1 and second 2 transistors, oscillations of the local oscillator are applied, and the input signal is fed to the bases of the third 10 and fourth four transistors.

When the oscillation of the local oscillator is turned off, the diodes 6-9 are closed, and in the emitters of the transistors 10 and 11, only sources 14 and

15 current with a large internal resistance significantly exceeding the value of resistors 12 and 13. Therefore, the gain of the cascade on these transistors 10 and 11 is negligible and there is no signal at the output of the frequency converter. When switching on the oscillator, for example, in its first half period, the polarity of the voltage

on the collectors T1) of the anzistors 1 and 2, the diodes 7 and 8 open and the diodes 6 and 9 remain closed. As a result, the resistors 4 and 5 through the open diodes 7 and 8 are connected in parallel and reach the emitter of the transistor 10, which leads to an increase in amplifying the cascade on the transistor 10 by decreasing the yi depth of its negative feedback. On resistor 12, select-amplified input signal, which is then fed to the output of the frequency converter. In the second half-period, oscillator oscillations open diodes 6 and 9, and diodes 7 and 8 close, disconnecting resistors 4 and 5 from the emitter of the transistor 10, Resistors 4 and 5 are connected through open diodes 6 and 9 to the emitter of the transistor

15

889752

11, thereby reducing the depth of the negative feedback and increasing the gain of the stage J on the transistor 11. Now the amplified signal is released on the resistor 13, and on the resistor 12 it becomes preliminarily small,

, Q Thus, at the symmetric output of the frequency converter, a voltage is formed that is proportional to the product of oscillations of the input signal and the signal of the local oscillator, the spectrum of which contains the components of the converted frequencies. In the frequency converter, there is no voltage overload, since the diagonal of the ring diode bridge is connected to Q Transistors 10 and 11 with emitters, common amplitude signal voltages are applied in amplitude. As a result, the junction points of the diodes are equipotential 25 The voltage and unlocking voltage on closed diodes is zero.

Thus, the overload threshold of the frequency converter over voltage does not depend on the parameters of the diodes, but is determined by the mode of operation of the amplifier stages on transistors 10 and 11,

Claims (1)

Invention Formula A frequency converter containing a differential amplifier, implemented on the first and second transistors, the emitters of which are combined and connected via the first current source to the common bus, collectors through the first and second resistors respectively connected to the power supply bus, and the bases are from convert # 11x signals. ring diode bridge, made on four according to the included diodes, one of the diagonals of which is connected between the collectors of the first and the second transistor of the differential amplifier, the third and fourth transistors, the bases of which are the input of another convertible signal, the third and fourth resistors, The first terminals of which are connected to the collectors of the third and fourth transistors, respectively, as well as the second current source, the output of which is 13889754 connected to the emitter of the third power supply bus, the second transistor, differing in the third and fourth resistors the fact that, in order to expand the dynamics connected to a common bus, a friend of the dyal range, the third reference gond of the ring diode bridge was introduced the current point connected between the bus is connected between the emitters of the third power supply and collector of the fourth and fourth transistors, a collector transistor, the inputs of which are the output of the second current source connected to the user frequency.