SU1561189A1 - Crystal oscillator - Google Patents

Abstract

The invention relates to radio engineering. The purpose of the invention is to increase the stability of two-frequency generation. The quartz gd contains a quartz resonator 1, transistors 2 and 3, resistors 4-7, capacitors 8-11 and voltage dividers 12 and 13, consisting of resistors 14-17. The goal is achieved by introducing a series circuit from resistor 7 and capacitor 11 The junction point of which is the switching point of one output of the quartz resonator 1, the other output of which is connected to the base of transistor 2. This leads to the realization of g-r with quartz resonator 1 in the feedback circuit and to the occurrence of stable signal generation at two frequencies of the same quartz 1st resonator 1. 1 Il.

Description

The invention relates to radio engineering and can be used in synthesizers often *.

The purpose of the invention is to increase the stability of two-frequency generation.

The drawing shows a circuit diagram of a crystal oscillator.

The crystal oscillator contains a quartz-emitter resonator 1, first and second transistors 2 and 3, first to fourth resistors 4-7, first to fourth capacitors 8-11, first and second voltage divider 12 and 13. 15 The first voltage divider contains the fifth and sixth resistors 14 and 15, the second, the voltage divider - the seventh and eighth resistors 16 and 17.

The crystal oscillator works barely-j 20 blowing way.

The fifth and eighth resistors 14-17 create a corresponding voltage drop at the bases of the first and second transistors 2 and 3. 25

A quartz oscillator is a self-oscillator of the frequencies fj and f ^ ,. where f, is the fundamental frequency of the quartz resonator G; fg is the frequency of the third harmonic of the quartz resonator-ed pa 1. Frequency is generated in a three-point capacitive circuit made on quartz resonator I, second and third capacitors 9 and 10, transistor 2. The frequency of quartz oscillator 1 is excited in the circuit, which is performed on the first • transistor 2, which is an emitter follower (for frequency fj), the emitter of which is connected to an amplifier on the second • transistor 3, made according to the scheme with a common base. The collectors of the first and second transistors 2 and 3 are connected in series, the fourth resistor 7 is the fourth capacitor 11. 45 The connection point of the fourth resistor 4 and the fourth capacitor 11 is the point of connection of one terminal of the quartz resonator 1, the other terminal of which is connected to the base of the first transistor 2, forming a positive feedback circuit at a frequency f, i.e. a crystal oscillator with a quartz crystal is implemented. resonator in the feedback circuit.

So, in the capacitive three-point circuit made on the first transistor 2, and in the circuit with quartz resonators and the feedback circuit on the first and second transistors 2 and 3, the excitation conditions are simultaneously satisfied, respectively, at frequencies f _J;

those. balance conditions of phases and amplitudes, which leads to the emergence of stable generation of signals at two frequencies f, and f _{3 of} one quartz resonator 1.

The first capacitor 8 at the generation frequency connects the base of the second transistor 3 to a common bus.

The transmission coefficient of amplifiers made on the first and second transistors 2 and 3 is established by selecting the resistances of the first and third resistors 4-6.

Claims (1)

Claim A quartz oscillator containing the first and second transistors, the emitters of which are combined and connected via the first resistor to a common bus, whose bases through the first and second voltage dividers respectively are connected to a power source, and the collectors are respectively connected through the second and third resistors to the power bus , the first output of which is connected to the base of the first transistor, the first capacitor, which is connected between the base of the second transistor and the common bus, the second and third capacitors, the first pins s are connected respectively to the base and the collector of the first. transistor, in contrast to the fact that, in order to increase the stability of dual-frequency generation, a fourth resistor is inserted, the first terminal of which is connected to the collector of the first transistor, and a fourth capacitor, the first terminal of which is connected to the collector of the second transistor, while the second terminals of the fourth a resistor, a fourth capacitor, and a crystal resonator are combined; the second terminals of the second and third capacitors are connected to the emitter of the first transistor.