SU1596430A1 - Mixer - Google Patents

Abstract

This invention relates to frequency converters. The purpose of the invention is to increase the degree of suppression of the combination side spectral components. The mixer is made in an annular circuit and contains transformers 1 and 3, diodes 8-11, signal source 2, local oscillator 5 and load 4. An oscillatory serial LC circuit 7 tuned to the frequency of the second harmonic of the local oscillator is introduced to increase the degree of suppression of the combinational side spectral components. (source 2). A mixer version has been approved, made on the basis of a balanced diode switching circuit. 2 Il.

Description

The invention relates to radio engineering, in particular to frequency converters, and can be used in exciters of radio transmitters, in radio receivers and in other devices.

The purpose of the invention is to increase the degree of suppression of the combination side spectral components.

FIG. 1 shows a schematic diagram of the mixer; Fig. 2 shows the same version using a balanced circuit for incorporating nonlinear elements (diodes).

The mixer, made according to the ring circuit and containing the first transformer.tor 1, the first signal source 2, the second transformer 3, the load 4, the second signal source 5 (heterodyne), block 6 of nonlinear elements, serial LC-coitur 7, the first diode 8 of block 6 , the second diode 9 of block 6, the third diode 10 of block 6, the fourth diode 11 of block 6.

The mixer contains the first transformer 1, the primary winding of which is connected to the output of the signal source 2, the second transformer 3, the secondary winding of which is connected to the load 4, the signal source 5, which is connected between the midpoint of the secondary winding of the first transformer 1 and the midpoint of the primary winding of the second transformer 3 nonlinear elements, for example, semiconductor diodes of block 6, which are connected between the ends of the secondary winding of the first transformer 1 and the ends of the primary winding of the second transformer 3. In addition, the mixer contains a series oscillating circuit 7, which is connected between the load 4 and the output of the signal source 2 and is tuned to the frequency of the second harmonic of the second signal from the signal source 5 and the common bus to which is connected, the anime end of the primary winding of the first transformer 1 , the secondary winding of the second transformer 3 and the load 4 ...

The mixer works as follows.

Two signals of different frequencies, different levels from the source of the second signal 5 and from the source of the first signal 2, respectively, are supplied to the middle terminals of the respective windings of transformers 1 and 3 and to the primary winding of transformer 1. Due to the nonlinearity of the nonlinear elements of the diodes 8-11, side oscillations occur in them under the action of signals, passing, although weakened, to the output of the mixer (to the load 4) along with the intermediate frequency signal

appearing on the primary winding of the transformer 3.

In a mixer with an annular circuit for switching on nonlinear elements (Fig. 1), theoretically, with ideal coincidence of the characteristics of nonlinear elements of block 6, an intermediate frequency signal is present at the mixer output and there are no combination side spectral components of the 5th order inclusive and components with input frequencies signals. In the balanced mixer (Fig. 2), there is no output signal at the output of the second signal and some of the combination side spectral components of even and odd order are weakened.

However, in reality, at the output of both mixers (Fig. 1, 2), all the combination side spectral components are present, although weakened. The highest level of side oscillations at the mixer output has the second harmonic of the strongest of the mixer input signals, which acts as a local oscillator signal for the mixer. If the second harmonic of the second signal (the signal of the local oscillator) is fed to the input of the mixer together with the input signal, which is done with the help of a serial LC circuit 7, then this harmonic will affect the level of the combination side odd order. This is due to the fact that the combination side oscillations of odd order, in the absence of a sequential LC circuit 7, are determined by odd powers of the polynomials in the decomposition of the currents of nonlinear elements by the powers of the voltages on these nonlinear elements. If there is a second harmonic at the input, the second and higher even degrees of the polynomials will also contribute to the value of the combination side spectral components of an odd order. And since usually the signs of the polynomial coefficients at 2nd: And 3rd degree of voltage and at 4th and 5th degrees x are opposite, the proposed mixer leads to a decrease in the level of combination side oscillations of an odd order of the form 2f2 ± fi; 3f2 ± 2f 1., etc., where f 1 is the frequency of the input (first) signal: f2 is the heterodyne frequency of the second signal).

Since, in the radio transmitter exciters, the frequency of the local oscillator in the output mixer is unchanged in a wide frequency range of the signal at the mixer output (in load 4), this compensation will be observed throughout this frequency range.

CE formula of invention

An annular circuit mixer, characterized in that, in order to

increase the degree of suppression of Raman side spectral components between the signal input and output

the mixer is a serial LC circuit with a resonant frequency equal to: 2 fr / where fr is the local oscillator frequency.

FIG. 2

T

Claims (1)

Claim The mixer is made according to the ring scheme, which is based on the fact that five 1596430 6 increase the degree of suppression of Raman side spectral components between the signal input and the output mixer entered a serial U circuit with a resonant frequency equal to; 2 T _g where T _g is the frequency of the local oscillator. ι 2