SU1385240A1 - Crystal frequency modulator - Google Patents

Abstract

The invention relates to communication technology and can be. used to generate a frequency modulated signal. The purpose of the invention is to reduce spurious amplitude modulation (AMP). The quartz frequency modulator contains a transistor 1, resistors 2, 3, 4, phasing capacitors 5, 6, tunable frequency-setting circuit 7 with a quartz resonator, blocking capacitors 8, 9, buffer cascade 10, filter 11 lower frequencies, paraphase amplifier 12, additional ones resistors 13, 14. In the device entered varicaps (B) 15 ,. 16. The increase in capacitances B 15 and B 16, connected between the base and the emitter, the emitter and the collector of transistor 1, leads to a decrease in the amplitude output signal. The voltage arriving at 815 is phase shifted relative to the PAM envelope by 180, and the voltage going to B 16 is in phase with the PAM envelope. Therefore, when put, the half-wave of the PAM function of the capacitance B 15 and B 16 will increase, and with negative. - decrease, which will reduce the PAM of the output signal. 1 il. S (l

Description

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ABOUT

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The invention relates to a communication technique and can be used to generate a frequency modulated signal.

The purpose of the invention is to reduce spurious amplitude modulation (AMP).

The drawing shows a structural electrical circuit of the proposed quartz frequency modulator.

The quartz frequency modulator contains a transistor 1, resistors 2-4, first 5 and second 6 phasing capacitors, tunable frequency-to-close circuit 7 with a quartz resonator, first 8 and second 9 blocking capacitors, buffer cascade 10, low-pass filter 11, paraphase amplifier 12, additional resistors 13 and 14, the first 15 and the second 16 zarykapy.

Quartz frequency modulator works as follows.

When the harmonic modulating signal U (t signal at the output is

and (si.),

where Wj, is the main generation frequency; frequency deviation caused

exposure; L is the modulation frequency. The voltage of the modulating signal U (t, fl) applied to the control input modulates the frequency of the output signal. The output signal through the buffer stage 10 is fed to the input of the filter 11, the output of which allocates a low voltage modulation voltage

if .m costot -i / p,

where Vp is the amplitude of the output signal; Shd - depth PAM;

1 — phase shift between the PAM envelope and the cosine-frequency component of the frequency deviation; K, j, - conversion factor

filter 11.

Voltage U goes to para-phase amplifier 12, the antiphase voltages from the outputs of which are fed through additional resistors 13 and 14 to the cathodes of the first 15 and second 16 varicaps, which causes a change in their capacitances between the base and the emitter and also between the emitter and the collector

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rum transistor 1. Experimental studies have shown that a change in capacitances connected between the base and emitter, emitter and collector of transistor 1 leads to a change in the amplitude of the output signal. Increasing these capacitances leads to a decrease in the amplitude of the output signal. The voltage supplied from the outputs of the paraphase amplifier 12 to the first varicap 15 through the additional resistor 13 is phase shifted relative to the PAM envelope by 180, and the voltage to the second varicap 16 through the second additional resistor 14 is in phase with the PAM envelope . Consequently, at a positive half-wave, the PAM function of the capacity of the first 15 and second 16 varicaps increases, while at a negative one, they decrease, which leads to a decrease in the PAM output signal.

Resistors 2–4 provide the constant current mode of transistor 1. The first 8 and second 9 block capacitors connect the high frequency circuit 7 to the collector circuit of the transistor 1 over high frequency. The frequency base circuit 7 is tunable, the first 5 and the second 6 Phasing capacitors and the first 15 and second 16 varicaps provide a phase balance condition at the generation frequency.

Claims (1)

Invention Formula A quartz frequency modulator containing a transistor whose collector is connected to the power bus, and whose base and emitter through appropriate resistors are connected to the power bus and the common bus, the first and second phasing capacitors, the first steps of which are connected respectively to the transistor and the emitter of the transistor , tunable frequency circuit with a quartz resonator, the first output of which is connected to the Tpansii base; the second output of which is connected to the bias bus directly and through the first blocking capacitor - to the common bus, and the third input of which is the control input of the quartz frequency modulator, the second blocking capacitor, which is connected between the collector of the transistor and the common bus, is a series-connected buffer stage. 13852404 a low-pass filter and an amplifier, which is connected between the second level, the input of the buffer stage is connected to the second condenser capacitor to the emitter of the transistor, which is connected to the power supply bus, and the amplifier is subtracted by the fact that, in order to complete it, in the form of a paraphase amplifier, reducing the parasitic amplitude mono-inverse and inverse ko-modulation outputs, introduced the first varicap, which through the appropriate additional connected between the second output resistors connected to the first phased-in capacitor and the original conclusions of the first and the emitter of the transistor, the second one of the second phasing capacitors.