RU2285331C2 - Broadband balanced mixer incorporating provision for mirror-channel phase suppression - Google Patents

Abstract

FIELD: radio engineering.

SUBSTANCE: proposed balanced mixer is designed for use in receiving equipment of VHF, SHF, and UHF communication lines to suppress mirror channel using 3 dB directional couplers. Data signal 21 and heterodyne signal 22 (Fig. 2) are supplied to mixer components 1-4 through broadband microwave-signal power splitter built around four directional couplers 23-26 and two matched loads 27. Signals 21 and 22 are applied to inputs of primary and secondary lines of directional coupler 23, respectively, and are uniformly distributed among four outputs of power splitter in triple frequency band. Integrated intermediate-frequency signals arriving from mixing components 1, 2 and 3, 4 are passed through low-pass filters 5, 6, and summed up in quadrature IF signal adder 7, and mirror conversion signals are subtracted.

EFFECT: ability of broadband mirror-channel suppression.

1 cl, 7 dwg

Description

The invention relates to the field of radio engineering and can be used in receiving communications equipment meter, decimeter and centimeter wavelength ranges.

The closest technical solution to the proposed mixer is a low-noise two-balanced mixer with phase suppression of the mirror channel, in which the local oscillator is fed through a quadrature divider, and the signal through a common-mode divider [1], figure 1 shows the structural diagram of the prototype, where:

21 - common mode power divider;

22, 23, 24 - directional 3 dB couplers as quadrature power dividers;

7 - directional 3 dB coupler as a quadrature adder of intermediate frequency signals;

1, 2, 3, 4 - mixing elements;

5, 6 - low-pass filters;

8, 25 - ballast loads;

26 - signal input;

27 - the input of the local oscillator.

The disadvantage of this mixer is the relatively narrow band of suppression of the mirror channel, limited by the working band of the quadrature and common mode dividers.

To obtain wideband suppression of the mirror channel according to known circuit solutions, it is necessary to use multi-stage quadrature and in-phase power dividers, which are distinguished by the complexity of implementation and unacceptable dimensions.

The aim of this invention is the construction of a broadband (up to triple overlap) balanced mixer with phase suppression of the mirror channel based on 3 dB directional couplers.

Figure 2 shows the structural diagram of the proposed mixer, where:

23, 24, 25, 26 - directional 3 dB couplers as quadrature power dividers;

1, 2, 3, 4 - mixing elements;

5, 6 - low-pass filters;

7 - directional coupler as a quadrature adder of intermediate frequency signals;

8, 27 - matched loads.

The mixer contains the first 1, second 2, third 3 and fourth 4 mixing elements, the first 5 and second 6 low-pass filters, an output directional coupler 7 and a balanced load 8, output 9 of the first 1 and output 10 of the second 2 mixing elements are connected in different phases to input 11 of the first low-pass filter 5, output 12 of the third 3 and output 13 of the fourth 4 mixing elements are connected in different phases to input 14 of the second low-pass filter 6, output 15 of the first low-pass filter 5 is connected to the input arm 16 of the primary output line is directed of the second coupler 7, the output 17 of the second low-pass filter 6 is connected to the input arm 18 of the secondary line of the output directional coupler 7, the output arm 19 of the primary line of the output directional coupler 7 is connected to the matched load 8, the output of the intermediate frequency signal of the mixer is the output arm 20 of the secondary output line directional coupler 7.

With the aim of broadband suppression of the mirror channel, the signal 21 and the local oscillator 22 are supplied to the mixing elements 1, 2, 3, 4 through a broadband microwave power divider [2]. The power divider contains the first 23, second 24, third 25 and fourth 26 directional couplers and matched loads 27. The input 28 of the first mixing element 1 is connected to the first output of the divider 29, the input 30 of the second mixing element 2 in the opposite phase is connected to the second output of the divider 31, the input 32 of the third mixing element 3 is connected to the third output of the divider 33, the input 34 of the fourth mixing element 4 in the opposite phase is connected to the fourth output of the divider 35. The input arm 21 of the primary line and the input arm 22 W the lines of the first directional coupler 23 are respectively the input of the signal and the input of the local oscillator of the mixer. The first output of the divider 29 is the output arm of the primary line of the second directional coupler 24, the third output of the divider 33 is the output arm of the secondary line of the fourth directional coupler 26, the fourth output of the divider 35 is the output arm of the primary line of the fourth directional coupler 26, the second output of the divider 31 is the output arm of the secondary the lines of the third coupler 25, to the input arms 36, 37 of the secondary lines of the second 24 and third 25 directional couplers connected matched loads 27, the input square The primary line fourth of the fourth directional coupler 26 is connected to the output arm 39 of the secondary line of the second directional coupler 24, the input arm 40 of the secondary line of the fourth directional coupler 26 is connected to the output arm 41 of the primary line of the third directional coupler 25, the input arm of the primary line of the third directional coupler 25 connected to the output arm 43 of the primary line of the first directional coupler 23, the output arm 44 of the secondary line of the first directional coupler 23 is connected to Khodnev shoulder 45 of the primary line of the second directional coupler 24.

To ensure the required phase ratio, the intermediate frequency signals of the first 1 and second 2 mixing elements connected to the first 28 and second 30 outputs of the divider are added together, as well as the intermediate frequency signals of the third 3 and fourth 4 mixing elements connected to the third 32 and fourth 34 outputs of the divider.

The combined intermediate frequency signals from the first 1 and second 2 mixing elements, as well as from the third 3 and fourth 4 are added together in the quadrature adder of the intermediate frequency signals, and the mirror signals are subtracted.

Figure 3 shows the phase relationships at the outputs of the power divider.

Figure 4 shows the electric circuit diagram of the proposed mixer.

Figure 5-7 shows the experimental characteristics of the proposed mixer.

The mixer operates as follows.

The signal supplied to the input 21 of the power divider is divided evenly into four outputs of the divider in the triple frequency band [2] and has the phase relationships shown in Fig.3. The local oscillator supplied to the input 22 of the power divider is divided evenly into four outputs of the divider in the triple frequency band and has the phase relationships shown in Fig.3.

Taking into account that the phase of the intermediate frequency signal is defined as the phase difference between the local oscillator and the signal (with f _pc = f _g -f _s ), and taking into account the polarity of the switching of the mixing elements 1 ... 4, we determine the phase value of the intermediate frequency signals at outputs 9, 10, 12, 13 as follows:

φ _be9 = 180 ° -90 ° = 90 ° - phase of the intermediate frequency signal (IF) at output 9;

φ _pc10 = 0 ° -90 ° + 180 ° = 90 ° - phase of the IF signal at output 10;

φ _be12 = 135 ° -315 ° = -180 ° - phase of the IF signal at output 12;

φ _be13 = 135 ° -135 ° + 180 ° = 180 ° - phase of the IF signal at output 13,

those. the phase shift of the IF signals at the input 18 of the quadrature adder relative to the IF signal at the input 16 is:

φ _pc18 -φ _pc16 = 90 °,

provided that the low-pass filters 5.6 are identical. The IF signals, after summing in the quadrature adder, are allocated at the output of the intermediate frequency 20.

For the case of a mirror transformation (f _pch = f _sk -f _g ),

the phase of the IF signal of the mirror channel (RF) at the outputs 9, 10, 12, 13 is defined as follows:

φ _{pch zk9} = 90 ° -180 ° = -90 ° - phase of the inverter signal zk at output 9;

φ _{pch zk10} = 90 ° -0 ° + 180 ° = 270 ° - phase of the inverter signal zk at output 10;

φ _{pch zk12} = 315 ° -135 ° = 180 ° - phase of the inverter signal zk at output 12;

φ _{pch zk13} = 135 ° -135 ° + 180 ° = 180 ° - phase of the inverter signal zk at output 13.

And the phase shift of the IF signal zk at the output of the 18 quadrature adder is equal to:

φ _{pk zk18} -φ _{pk zk16} = -90 °.

PChz signals after summing in the quadrature adder are allocated in the load resistor 8.

On Fig 5, 6, 7 shows graphs of the dependence of the parameters of the mixer on the frequency, where:

K _P - power conversion coefficient;

K _N - noise figure;

σ _zk - suppression of the mirror channel.

INFORMATION SOURCES

1. Design of radio receivers. Ed. A.P. Siversa: M., Sov. radio, 1976

2. USSR author's certificate No. 1467622, IPC ⁴ N 01 P 5/12, publ. 1989.

Claims (1)

A broadband balanced mixer with phase suppression of the mirror channel, containing the first, second, third and fourth mixing elements, two low-pass filters, an output directional coupler and a balanced load, the outputs of the first and second mixing elements are connected in different phases to the input of the first low-pass filter, outputs the third and fourth mixing elements are connected in different phases to the input of the second low-pass filter, the output of the first low-pass filter is connected to the input arm of the primary line the output directional coupler, the output of the second low-pass filter is connected to the input arm of the secondary line of the output directional coupler, the output arm of the primary line of the output directional coupler is connected to the matched load, the output arm of the secondary line of the output directional coupler is the signal output of the mixer intermediate frequency, characterized in that, in order to broadband suppression of the mirror channel, the signal and the local oscillator are fed to the mixing elements through the broadband A microwave signal power splitter consisting of four directional couplers and two matched loads, the input of the first mixing element is connected to the first output of the divider, the input of the second mixing element in the opposite phase is connected to the second output of the divider, the input of the third mixing element is connected to the third output of the divider, the input of the fourth the mixing element in the opposite phase is connected to the fourth output of the divider, the input arm of the primary line of the first directional coupler is the input mixer needle, the input arm of the secondary line of the first directional coupler is the input of the mixer oscillator, the first output of the divider is the output arm of the primary line of the second directional coupler, the third output of the divider is the output arm of the secondary line of the fourth directional coupler, the fourth output of the divider is the output arm of the primary line of the fourth directional coupler , the second output of the divider is the output arm of the secondary line of the third directional coupler, to the input coordinated loads are connected to the shoulders of the secondary lines of the second and third directional couplers, the input arm of the primary line of the fourth directional coupler is connected to the output arm of the secondary line of the second directional coupler connected to the output arm of the fourth line of the third directional coupler, the input arm of the primary line the third directional coupler is connected to the output arm of the primary line of the first directional tvetvitelya, the secondary side output port of the first directional coupler connected to the input line of the second primary shoulder directional coupler.

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