RU4874U1 - FREQUENCY-MODULATED QUARTZ GENERATOR - Google Patents

Abstract

A frequency-modulated quartz oscillator containing a series-connected resistor, one terminal of which is connected to the input terminal, a first quartz resonator with a first reactance connected in parallel and a second reactance connected to the active part of the generator, the other terminal of which is connected simultaneously with one terminal of the varicap and with input terminal, the other output of the varicap is connected to a common point of the resistor and quartz resonator, characterized in that the series-connected a second quartz resonator and a capacitor connected in parallel with the first quartz resonator.

Description

FREQUENCY QUANTIZED QUARTZ GENERATOR

The proposed useful model relates to the field of radio engineering and can be used in various radio equipment for creating frequency-modulated oscillators with quartz frequency stabilization with high electrical parameters (increased frequency deviation and a wide range of modulating frequencies).

Known crystal oscillators with direct frequency modulation by using a varicap as a control element, connected, as a rule, in series with a quartz resonator, described, for example, in the literature: A, D, Artym Theory and methods of frequency modulation M ,, Gosenergoizdat, I96I, GB Altshuller Frequency control of quartz oscillators M., Communication, 1975, GG Shitikov Stable oscillators of meter and decimeter waves M, Radio and communication, 1983.

However, the devices described in the literature do not allow a large frequency deviation and a large slope of the control characteristics with high frequency stability.

The closest in technical essence to the proposed device is the device described in the book of GB Altshuller Frequency control of crystal oscillators, M., Communication, 1975, p. 304, Fig. 12.1.1 on pL46.

An equivalent circuit of the FM quartz oscillator is shown in figure 1, where indicated;

1 - resistor

2,4,5 - reactance,

3 - varicap,

NIZV 5/32

The prototype device contains a resistor I connected in series, one output of which is connected to the input terminal, a quartz resonator 7, in parallel with which a reactance 4 and a reactance 5 are connected to the active part of the generator 6.

The common point of reactance 2, varicap 3 and the other output of the active part of the generator 6 are connected to another input terminal.

In this case, the other conclusions of reactance 2 and varicap 3 are connected to a common point of resistor I, crystal oscillator 7 and reactance 4.

The device operates as follows.

When applying the modulating voltage C through the resistor I to varicap 3, the capacitance, and, consequently, the frequency of the crystal oscillator with the modulation frequency Si, changes.

The reactive resistance 4 connected in parallel with the quartz resonator 7 serves to reduce non-linear distortions and obtain non-linear distortions and obtain a linear characteristic for controlling the frequency of the generator.

The reactance 5 serves to select the initial detuning of the quartz resonator. Often, the initial detuning of a frequency-modulated crystal oscillator is selected near the series resonance. The reactance is usually of an inductive nature to increase the steepness of the control characteristic, however, this increases the frequency instability and increases the loss in the crystal oscillator. Torah.

To eliminate this drawback, a device containing a series-connected resistor, one output of which is connected to the input terminal, a quartz resonator with a first reactance connected in parallel and a second reactance connected to the active part of the generator, one output of which is connected simultaneously to one output of the varicap and K the input terminal, the other output of the varicap is connected to the common point of the resistor and the quartz resonator, the second quartz resonance is connected in series op and a capacitor connected in parallel to the first crystal.

Figure 2 shows the proposed device, where indicated:

I is the resistor

Z is the capacitor

3 - varicap,

4,5 - the first and second reactance,

6- active part of the generator,

7 - the first quartz resonator,

8 second quartz resonator.

The proposed device contains a first quartz resonator 7, in parallel with which a first reactance 4 is connected and a second quartz resonator 8 and a capacitor 2 are connected in series. A second reactance 5 connected to the active part of the generator b is connected in series with this connection. The common terminal point of varicap 3 and the active part of the generator b is connected to the input terminal of the device. Another input terminal is connected through a resistor I to a common point of the varicap 3 and a parallel connection of the first reactance 4, the first quartz resonator 7 and a chain of series-connected second quartz

3. resonator 8 and capacitor 2,

The device works similarly to a zrototype generator. However, due to the fact that a second resonator 8 is connected in parallel with the first quartz resonator 7 with a capacitor 2 connected in series, the frequency deviation and the steepness of control increases by 2 times without compromising stability and reducing losses in the oscillatory circuit.

In the proposed device, the varicap 3 is not shunted by reactive (inductive nature) resistance. The quartz resonator 8 is selected so that its frequency is less than the frequency of the quartz resonator 7, The capacitance of the capacitor 2 is selected so as to increase the frequency of the quartz resonator 8 and to compare the frequencies of the resonators 7 and 8.

Patent holder - Voronezh ShI of communication.

Deputy Chief Engineer Yu.V. Snezhko

4.

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Claims (1)

A frequency-modulated quartz oscillator containing a series-connected resistor, one terminal of which is connected to the input terminal, a first quartz resonator with a first reactance connected in parallel and a second reactance connected to the active part of the generator, the other terminal of which is connected simultaneously with one terminal of the varicap and with input terminal, the other output of the varicap is connected to a common point of the resistor and quartz resonator, characterized in that the series-connected a second quartz resonator and a capacitor connected in parallel with the first quartz resonator.