The high-frequency band of the piezoelectric filter

 

The invention relates to electronics and can be used for frequency selection signals. The technical result consists in providing a wider bandwidth and improving the Squareness of the amplitude-frequency characteristics of the filter with the low-frequency side. Filter (f) contains piezoresonator (PR) 1, 2, 6, 7, the coil windings connection (S) 8, 9, capacitors (C) 3, 5, 10, 11. The signal comes through matching To 10, 3 to the winding KEY 8 and PR 1. With winding connection CI 8 signal, shifted in phase by 180 degrees, comes to PR 6. Currents flowing through PR 1 and 6 are on nagruzochnom To 4. The outcome is the transfer function of a circuit equivalent to the bridge, each arm of which is included ETC. Another part of the circuit works similarly. Scheme F. in General equivalent to a two-tier bridge circuit bandpass filter of the fourth order. Maximum bandwidth equal to twice the frequency interval used ETC. In the schema to be consistent with the load impedance used two capacitive divider of 10, 3 and 5, 11. 1 Il.

The present invention relates to electronics and can be used for frequency villages is s, the first output of the first piezoresonator through the first capacitor is connected to a common bus, a second output of the first piezoresonator is connected to the first output of the second piezoresonator and simultaneously through the second capacitor with a common bus, a second output of the second piezoresonator through the third capacitor is connected to a common bus.

A disadvantage of the known device is that it implements the attenuation pole located only a high-frequency side of the filter bandwidth, and bandwidth does not exceed 15-20% of the width of the frequency interval of piezoresonator:

F=fp-fg,

where fpthe frequency of parallel resonance of piezoresonator;

fgthe frequency of the series resonance of piezoresonator.

The objective of the invention is to provide an implementation of wider bandwidth and better Squareness of the amplitude-frequency characteristics of the filter with the low-frequency side.

The problem is solved in that in the filter circuit entered an additional third and fourth piezoresonator, the first conclusions of which is connected to the second output of the first piezoresonator, the first and second inductor windings connection, and the fourth and the first output of the first inductor, the first output winding of the first inductor is connected with the second output of the third piezoresonator, the first output of the fifth capacitor is the output of the filter, and the second output is connected with the first output of the second inductor, the first output winding connection of the second inductor is connected with the second output of the fourth of piezoresonator, main conclusions of the first and second inductors, and the second leads of windings connection of the first and second inductors connected to a common bus.

Comparative analysis shows that the proposed solution differs from the prototype in that scheme we have introduced the third and fourth piezoresonator, the first conclusions of which is connected to the second output of the first piezoresonator, the first and second inductor windings connection, and the fourth and fifth capacitors, the first output of the fourth capacitor is the input of the filter, and the second is connected to the first output of the first inductor, the first output winding of the first inductor is connected with the second output of the third piezoresonator, the first output of the fifth capacitor is the output of the filter, and his second output coactively connected with the second output of the fourth of piezoresonator, second, the conclusions of the first and second inductors, and the second leads of windings connection of the first and second inductors connected to a common bus.

When comparing the proposed solutions not only prototype, but also with other known technical solutions in science and technology not found solutions with similar characteristics.

The drawing shows an electric diagram of the proposed device. The device comprises a first 1 and second 2 piezoresonator, the first output of the first piezoresonator through the first capacitor 3 is connected with a common bus, a second output of the first piezoresonator is connected to the first output of the second piezoresonator and through the second capacitor 4 with a common bus, a second output of the second piezoresonator through the third capacitor 5 is connected with a common bus, in addition, the device includes a third 6 and fourth 7 piezoresonator first conclusions which are interconnected and connected to the second output of the first piezoresonator 1, the first 8 and second 9 to the coil windings connection, and the fourth 10 and 11 fifth capacitors, moreover, the first output of the fourth capacitor is a filter input and the second output connected to the first output of the first inductor, the first conclusion oblock what is the output of the filter, and its second output is connected with the first output of the second inductor 9, the first output winding connection which is connected with the second output of the fourth of piezoresonator 7, main conclusions of the first and second inductors, and the second their conclusions windings connection connected to a common bus.

The device operates as follows.

The signal is fed to the input of the filter and through matching capacitors 10 and 3 is supplied to the coil of the first inductor and at the same time on piezoresonator 1. From a winding of a communication signal, shifted in phase by 180comes on piezoresonator 6. Currents flowing through piezoresonator 1 and 6, are deducted on the load capacitor 4. As a result, when the corresponding selection of the values of the circuit elements of this part of the circuit implements the transfer function of a circuit equivalent to a symmetric bridge, each arm of which included piezoresonator. Another part of the circuit works the same way. Thus, the circuit of the device as a whole is equivalent to a two-tier bridge circuit bandpass filter of the fourth order, the maximum bandwidth which is equal to twice the frequency interval used piezoresonator in which to negotiate Noe device has been pilot-tested, released a full set of design documentation, which made the samples for a number of professional receivers.

The source of information

1. Piezoelectric filters. I. I. Velikin, H. J. Gelmont, E. C. Zeljah. M: Communications, 1966, page 177, PL. 3.12.

Claims

The high-frequency band of the piezoelectric filter containing the first and second piezoresonator, the first output of the first piezoresonator through the first capacitor is connected to a common bus, a second output of the first piezoresonator is connected to the first output of the second piezoresonator and simultaneously through the second capacitor with a common bus, a second output of the second piezoresonator through the third capacitor is connected to a shared bus, characterized in that the filter circuit entered an additional third and fourth piezoresonator, the first conclusions of which is connected to the second output of the first piezoresonator, the first and second inductor windings connection, and the fourth and fifth capacitors, the first output of the fourth capacitor is the input of the filter, and the second is connected to the first output of the first inductor, the first output winding of the first coil induct the house filter and its second output is connected with the first output of the second inductor, the first output winding connection of the second inductor is connected with the second output of the fourth of piezoresonator, main conclusions of the first and second inductors, and the second leads of windings connection of the first and second inductors connected to a common bus.

 

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FIELD: radio engineering, possible use in radiolocation stations working with two multi-frequency generators.

SUBSTANCE: directional filter contains two low-and-high-pass filters, a T-joint and two two-channel commutators. Channels of commutator rotors are coupled with shoulders of T-joint, which amount to λ/4 or λ/2 respectively with consideration of rotor channel lengths, where λ - wave length on shoulders of the T-joint.

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