RU1807555C - Band-pass piezoelectric filter - Google Patents

Abstract

Usage: electronics, communication technology, measurement technology. SUMMARY OF THE INVENTION: a piezoelectric bandpass filter comprises an input phase splitter, resonators, a resistor, a capacitor, an expansion inductor. The device provides a reduction in the noise level, since the input phase splitter and the expansion inductor are made on operational amplifiers. 1 ill. .

Description

 The invention relates to electronics and can be used in communication technology and in measurement technology.

The purpose of the invention is to reduce the level of introduced noise and increase the manufacturability of production, reduce the overall dimensions of the device.

The drawing shows an electrical diagram of the proposed filter. The band-pass filter consists of an input phase splitter 1, piezoresonators 2 and 3, a load resistor 4, a capacitor 5 and an expansion inductance 6. The input phase splitter 1 is made on non-inverting 7 and inverting 8 amplifiers and a voltage divider on resistors 9. In this case, the input the inverting amplifier 8 and the input of the resistive divider 9 are combined and are the input of the filter, and the outputs of the non-inerting amplifier 7 and the inverting amplifier 8 are connected to the first terminals of piezoresistors 2 and 3, respectively, the second conclusions are piezoelectric resistors 2 and 3 are connected and connected to the output terminal of the filter, and the load resistor 4, the capacitor 5 and the expansion inductance b

are connected parallel to the output of the filter, the Inductor is made in the form of an inductance simulator containing operational amplifiers 10 and 11, between the output and the inverting input of each of the operational amplifiers 10 and 11, resistors 12 and are included. 13, respectively, an additional resistor 14 is connected between the output of the operational amplifier 10 and the non-inverting input of the operational amplifier 11, a capacitor 15 is connected between the output of the operational amplifier 11 and a non-inverting input of the operational amplifier 10, a second additional resistor 16 is connected to the non-inverting input of the operational amplifier 10 and a common bus, wherein the non-inverting input of the operational amplifier 11 is the input of an inductance simulator.

 The filter works as follows. Signal E is applied to the input terminal of the filter and. the passage through the input phase splitter 1, at points A and B becomes equal, respectively:

Eeyore E; UB-K E; Ua - UB,

Joint venture

with

00

about

and

eaten eaten

where k is the gain of operational amplifiers 7 and 8. On the summing device (in t. C), these two voltages will have values, respectively:

Ua

Ha + Z

V2

UB

Xv + Z

where Xa and Xb are the resistances of the piezoelectric resonators 2 and 3, respectively;

Z is the resistance of the adder formed by the parallel connection of the load resistor 4. capacitor 5 and the inductance simulator 6.

The value of the resulting voltage at the filter output will be equal to the sum of the voltage values Vi and V2, and will be:

V3

Ua Z Ua Z Xa + .Z Xb + Z

transfer function of the filter as a whole

t Uz Ha - XB E (Xa + Z) XB + Z)

corresponds to the transfer function of a symmetric bridge containing a piezoelectric resonator in each arm with a parallel circuit connected to it (formed by an inductance simulator 6 and a capacity of 5). The proposed device provides the operation of two piezoelectric resonators with just one (common) inductance simulator. Therefore, the proposed circuit has the following positive properties: the complexity of filter tuning is reduced by eliminating the winding and preparation of inductance coils: the temperature stability of the filter as a whole is improved by reducing the number of elements affecting the frequency response, the use of operational amplifiers instead of differential transformers and expansion coils extends the dynamic range

filter, which is equivalent to reducing the level of introduced noise. Using the proposed device can improve linearity up to 110 dB with test signals up to 2 V and thereby improve the signal-to-noise ratio,

Claims (1)

SUMMARY OF THE INVENTION A strip piezoelectric filter, made according to the differential-bridge circuit, in two shoulders of which the input phase shifter is turned on, and in the other two - the first and second resonators, respectively, and also including an expansion an inductor, a capacitor and a resistor, characterized in that, in order to reduce the noise level, an expansion inductor, a capacitor and a resistor are connected in parallel with the output a differential-bridge circuit, and the input phase shifter is made on a non-inverting and inverting amplifiers and a resistive voltage divider included at the input of a non-inverting power body, while the input of the inverting amplifier and the input res, the voltage divider are combined and are the input n of the input phase splitter and the inductor is made in the form of a simulator an inductance containing the first and second operational amplifiers, between the input and the inverting input of each of the operational amplifiers there is a corresponding resistor, a first additional resistor connected between the output of the first operational amplifier and a non-inverting input of the second operational amplifier, a capacitor connected between the output of the second operational an amplifier and a non-inverting input of the first operational amplifier, and a second additional resistor connected to the non-inverting input of the first operational amplifier, with a different conclusion a second additional resistor and a non-biasing input of the second operational amplifier are outputs of an inductance simulator.