SU959256A1 - Self-excited crystal oscillator - Google Patents

Description

(5th) QUARTZ AUTOGENERATOR

V. -

This invention relates to radio engineering and can be used as a source of high stability vibrations.

A quartz oscillator is known, containing a transistor of conduction pp, between the base and the collector of which the first resistor is connected, emitter: connected via a parallel connecting quartz resonator and the second resistor to the power supply bus and the base is connected to the collector via the junction-base. hp-n transistor transistor, / the emitter of which is connected to the drain of the field-effect transistor, the source of which is through the third resistor, and the drain through the first capacitor is connected to the common bus, but this device is not enough High stability 4acTotbi generated oscillations.

The purpose of the invention is to increase the frequency stability of the generated oscillations,

This goal is achieved by a quartz oscillator containing a transistor pp n conductivity, between the base and the collector of which the first resistor is connected, the emitter sub5: connected through a parallel connected crystal oscillator and the second resistor to the power supply bus at the base connected to the collector through the collector-base transition; torus pnp conductivity, the emitter of which is connected to the drain of the field-effect transistor, the source of which is through the third resistor, and the drain through the first capacitor is connected to the common bus-;

15 Not, the gate of the field-effect transistor — through the fourth resistor and through the second capacitor — is connected respectively to the amp and bus and to the base transis

2Q of the Torah pnp conductivity, and parallel to the third resistor is connected the third capacitor.

Claims (2)

The drawing shows an electrical circuit of a quartz oscillator. Quartz oscillator contains transistors 1 and 2 pp conductivity and pn conductivity, field effect transistor 3, crystal /, the first, second, third and fourth resistors, the first, second and third capacitors 9-11 Quartz auto-oscillator works as follows images. A two-pole device consisting of elements 1,2 and 5 (in which the output terminals - emitters of transistors 1 and 2 have an S-shaped characteristic. Field-effect transistor 3 sets the current through this two-terminal network. The current value must correspond to the position of the operating point on the falling part of the characteristic , defining a two-pole network, as a series connection of the negative resistance R (-) and some equivalent inductance. Thus, there is a closed secondary loop consisting of equivalent negative resistance R (-), a two-pole inductance, a quartz resonator 4 and a parallel RC circuit, where, C is the capacitance of the capacitor 9, and R is the output resistor of the field-effect transistor 3, for which the mode corresponding to the low output static characteristics is specified, satisfies a sufficiently large output impedance R and its unchanged with changes in voltage on the drain during the oscillation period.The condition | R (-) 7 RCJ where RO; is the resistance of the quartz resonator, leads to the appearance of a self-oscillating process in the circuit. In this case, the oscillating voltage on the drain of the field-effect transistor 3 or the emitter of the transistor 2 is in phase with the voltage on the base of transistor 2. The increase in voltage on the drain, which practically does not change the drain current, is accompanied by a similar change in the gate voltage, because a capacitor 10 with a base transistor 2. This corresponds to the fact that the operating point on the static output characteristic of the field-effect transistor 3 moves to another characteristic, corresponding to a higher gate voltage, as the drain voltage rises. In this way, the field effect transistor 3, with such a gate being turned on, has a much lower dynamic output resistance compared to the output resistance, determined eMfetM output static characteristics, which is used in the well-known circuit. Moreover, the dynamic output characteristic is non-linear, since the volt-ampere characteristic of direct transmission has a quadratic character. As the amplitude of oscillations in the drain increases, the average for the period the value of the output resistance decreases. This resistance through the capacitor 11 is connected in parallel to the capacitor 9 in the circuit of the oscillating system. As the cola increases, the decrease in the output resistance of the field-effect transistor 3, which shunt capacitor E, causes an increase in the resistance of losses in the oscillatory system, i.e. with the same initial modes with a sufficiently large factor of regeneration of the proposed generator and the known one, the first one establishes the self-oscillation mode with smaller amplitudes in comparison with the known one. This leads to a decrease in the frequency variation with respect to the frequency of the series resonance of the quartz resonator 4 due to the higher harmonics of the current and, consequently, to an increase in the frequency stability with variation of their values. The proposed generator allows to increase the frequency stability, reduce the parametric instability (due to the variation of the capacitance of the capacitor 9, which determines the excitation of the quartz resonator k at a given harmonic) - more than an order of magnitude and 3 times regime (due to the variation of the supply voltage). ). The proposed quartz oscillator has all the advantages of the well-known - efficiency, power dissipation on quartz in fractions of microwatts, suitability for micro-performance and has a higher frequency stability of the generated oscillations. The invention is a quartz oscillator containing a transistor ppr conductivity, between the base and the collector of which is included the first resistor, emitter