SU930573A1 - Frequency-modulated crystal oscillator - Google Patents

Description

(54) FREQUENCY MODULATED QUARTZ GENERATOR

The invention relates to radio engineering and can be used, in particular, in converting voltage to frequency, phase locked loop systems. A frequency-modulated 1 crystal oscillator is known, containing a first transistor connected according to a circuit with a common base, with a resistor in the emitter circuit and a resonant load in the collector circuit to which one electrode of the quartz resonator is connected through the second transistor 45, connected to the emitter follower circuit an inductance coil and a paraphase source of control of the "fl fl". However, in the known frequency-modulated crystal oscillator, the steepness of the frequency control characteristic is not high enough. The purpose of the invention is to increase the slope of the frequency control characteristic. For this purpose, a third transistor, connected according to a common base circuit, is inserted into a known frequency-modulated crystal oscillator; the collectors of the first and third transistors are directly connected, the emitters are connected through an inductance coil, the bases are connected to the corresponding outputs of a paraphase control source, and another electrode The quartz resonator is connected to the emitter of the third transistor. The drawing shows a circuit diagram of the device. The frequency-modulated crystal oscillator contains transistors 1-3, a quadrant resonator 4, a resistor 5, a resonant load 6, an inactivity coil 7, a paraphase control voltage source 8. The frequency-modulated quartz oscillator operates as follows. The CRN of the presence of a controlled voltage, the magnitude and polarity of which ensures the full opening of the transistor 1 of the cascade to the closing of the transistor 3, and the feedback signal from the emitter follower output of the transistor 2 passes through the series-connected crystal oscillator 4 and the inductance 7 to the emitter in this case) of the transistor 1. According to the expression for the relative frequency tuning of the crystal oscillator with a similar feedback circuit, the frequency of the generated oscillations is lower than the frequency of the crystal resonator 4. As the transistor 1 closes and the transistor 3 opens accordingly under the influence of a control voltage, the signal in the feedback circuit is redistributed between these transistors 1, 3 and the frequency of the generated oscillations increases. When transistor 3 is fully open and transistor 1 is closed, the signal in the feedback circuit passes the inductance 7 and the frequency of the generated oscillations reaches its upper limit. The magnitude of the differential control voltage and the pp applied to the bases of transistors 1 and 3 is usually not more than ten millivolts, even for the full switching of transistors 1 and 3 from the open state to the closed state. In this case, as shown by the experimental results, in the proposed quartz oscillator, a significant frequency tuning range is obtained, the average steepness of the control characteristic, obtained as the ratio of the electronic frequency tuning band to the control voltage value, in the proposed crystal oscillator is greater than preservation of other parameters - temperature, time, etc. frequency stability. The increased steepness of the control characteristics of the proposed quartz oscillator increases the sensitivity of, for example, FM demodulators made on the basis of the PLL, FM oscillators, voltage-frequency converters, and provides electronic frequency tuning at small control voltage amplitudes that allows to reduce the supply voltage of devices that produce a control voltage. In the proposed quartz oscillator, a high frequency stability is provided in the presence of an in-phase (parasitic) component in the control voltage due to interference in the control circuit and a change in the supply voltage. This is due to the fact that transistors 1 and 3 form a differential cascade, which, as is well known, is not very sensitive to common-mode noise. Formula of the Invention A frequency-modulated crystal oscillator containing a first transistor connected in a common base circuit, with a resistor in the emitter circuit and a junction load in the collector circuit to which one electrode is connected through the second transistor connected in the emitter follower circuit a quartz resonator, an inductance coil, and a paraphase control voltage source, characterized in that, in order to increase the steepness of the frequency control characteristic, a third transistor, connected in accordance with the circuit a common base, the collectors of the first and third transistors are connected directly, the emitters are connected through an inductance coil, the bases are connected to the corresponding outputs of a paraphase control voltage source, and the other electrode of the quartz resonator is connected to the emitter of the third transistor. Sources of information taken into account in the examination 1. US Patent No. 3302138, cl. 334-15, 1967 (prototype).

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Claims (1)

The claims “Frequency-modulated quartz oscillator containing the first transistor connected in accordance with a common base circuit, with a resistor in the emitter circuit and a resonant load in the collector circuit, to which one quartz resonator electrode is connected through the second transistor connected in accordance with the emitter follower circuit , an inductor and a paraphase source of control voltage, characterized in that, in order to increase the steepness of the frequency control characteristic, a third transistor is introduced, connected according to the scheme with a base, and the collectors of the first and third transistors are connected directly, the emitters are connected through an inductor, the bases are connected to the corresponding outputs of the paraphase control voltage source, and the other quartz resonator electrode is connected to the emitter of the third transistor.