SU650214A1 - Filter on acoustic surface waves - Google Patents

Description

one

The invention relates to radio engineering and can be used to build functional units of radio equipment and spectrum analyzers.

A filter on acoustic surface waves is known, in which the average frequency is controlled by a complex control unit in the form of an electron gun with a focusing system 1.

The closest technical solution to the invention is an acoustic surface wave filter containing a piezoelectric acoustic duct, radiating and receiving transducers, as well as an interdigital non-equidistant transducer for the operating frequency of the acoustic surface wave located on the acoustic duct between the radiating and receiving transducers 2.

However, the known filters have high insertion losses and the complexity of restructuring the average frequency of the filter.

The purpose of the invention is to eliminate the insertion loss and simplify the tuning of the average frequency of the filter.

The goal is achieved by the fact that the filter on acoustic surface waves, containing a piezoelectric acoustic conductor, emitting and receiving transducers, as well as counter-non-equidistant transducer for extracting the operating frequency of the acoustic surface wave, placed on the acoustic conduit between the emitting and receiving transducers, is additionally equipped with series-connected tunable a generator of sinusoidal oscillations, a phase matching unit and a varicap, with the output of the varicap nonequidistant union of a converter.

The drawing shows a functional electrical circuit of the proposed filter on acoustic surface waves.

The acoustic surface wave filter contains a piezoelectric acoustic conduit 1, radiating 2 and receiving 3 transducers, as well as a counter-non-equidistant transducer 4 dedicated to the operating frequency of the acoustic surface wave, placed on the sound conductor 1 between the radiating 2 and iriem 3 transducers, sequentially connected sinusoidal generator 5

oscillations, phase matching unit 6 and varicap 7, the output of the varicap is connected to an equivalent 1 by converter.

The filter on acoustic surface waves works as follows.

When an electrical signal of frequency / s is applied to the radiating transducer, the acoustic surface wave is emitted in the direction of the non-equidistant transducer 4. From the generator of 5 sinusoidal oscillations, through the phase matching unit 6, the variable signal 7 is fed to the frequency control fr. Under the following conditions: a) / s / g; b) coordination of the phases of the control signal of the generator of 5 sinusoidal oscillations and the signal of the acoustic surface wave is ensured; c) the frequency / s corresponds to the period of the electrodes of the section of the non-equidistant 4 transducer, a parametric amplification of the acoustic surface wave with a frequency of / s occurs. The amplified signal of the acoustic surface wave reaches the broadband receiving transducer from which the electrical signal of frequency / s is removed.

When changing the oscillator frequency 5 sinusoidal oscillations, conditions a, b are violated, and there is no parametric amplification of the acoustic surface wave. If the signal frequency changes, if the conditions a, b, are met, then the third condition will be met for the corresponding section of the non-equidistant converter, and amplification occurs at the frequency corresponding to this section. Thus, the average frequency of the amplitude-frequency characteristic of the filter on the acoustic surface waves is within the range defined by

amplitude-frequency; shea characteristic non-equidistant converter.

The proposed filter on acoustic surface waves has a simpler design due to the fact that there are no reflective structures, an absorbing element with unique properties, an electron gun and a focusing system.

Claims (2)

1. Patent of France No. 2244301, cl. N OZN 9/14, 1975. 2. Kariisky S.S. Signal processing devices on ultrasonic surface waves. M., “Owls. radio, 1975, p. 82