SU1656659A1 - Shf self-excited oscillator - Google Patents

Abstract

The invention relates to radio engineering. The purpose of the invention is to reduce the level of phase noise. The oscillator contains a bipolar transistor 1, resistors 2, 3, and 4, sources 5 and 6 of the power supply, a varicap 7, segments 8, 9, and 10 of the microstrip line, as well as isolation and blocking capacitors 1114. and positive feedback circuit 15. A change in the DC component of the collector current of transistor 1, proportional to the change in the generated power, is released at resistor 4. This voltage through the decoupling filter formed by segment 10 and capacitor 13 goes to varicap 7 and, by changing the frequency of the parallel circuit, gives an additional phase a shift that compensates for the initial phase increase due to the change in generated power. By selecting the voltage source 6 and the polarity of switching on the varicap 7, you can reduce the slope of the resulting phase-amplitude x-ki circuit with varicap 7 and transistor 1. Thus, the level of phase noise converted from amplitude noise is reduced. 1 silt (L S

Description

The invention relates to radio engineering. namely, microwave generators, and can be used in various radio systems to generate microwave oscillations.

The purpose of the invention is to reduce the level of phase noise.

The drawing shows the microwave oscillator.

 The auto-generator contains a bipolar transistor 1, the first 2, the second 3 and the third 4 resistors, the first 5 and second 6 power sources, varicap 7, the first (A / 4 length), 8, the second 9 and the third (I / 4 length) 10 segments microstrip line, separation capacitor 11, the first 12, the second 13 and the third 14 block capacitors and a positive feedback circuit. The bipolar transistor 1 collector is connected through the first section 8 of the microstrip line and the third resistor 4 to the first power source 5, the emitter to the common bus, and the base to the base divider formed by the first 2 and second 3 resistors and connected to the common point of the first segment 8 the microstrip line, and the third resistor 4, which is connected via a blocking capacitor 12 to the common bus; the collector of the transistor 1 is connected via the positive feedback circuit 15 and the separation capacitor 11 to the base The torus 1 is also connected via a coupling capacitor 11 to a parallel circuit formed by the varicap 7 and the second segment 9 of the microstrip line, the other end of which is connected to the second power source b and through the blocking capacitor 14 with a common bus.

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a capacitor 13 to a common bus and through the third (A / 4 length) segment 10 microstrip line to the common point of the first segment 8 microstrip line and the third resistor 4.

The device works as follows.

At the initial moment, free oscillations arise in the autogenerator circuit, due to the inclusion of power sources, electrical fluctuations. Due to the positive feedback circuit, these initial vibrations are amplified. As the amplitude of the oscillations increases, the nonlinearity of the transistor begins to manifest and the gain decreases to a level at which only the attenuation of the oscillations in the load is compensated. Due to the nonlinearity of the transistor, its phaeo-amplitude characteristic has a certain steepness, as a result of which the amplitude noise is converted to phase noise in the autogenerator. To eliminate such a transformation and accordingly minimize phase noise, feedback is introduced to reduce the steepness of the phase-amplitude characteristic of the transistor at the operating point. The change in the current component of the collector current, proportional to the change in the generated power, is released on the third resistor 4, and this voltage through the decoupling filter formed by the microstrip line section 10 and the blocking capacitor 13 goes to the varicap 7 and, changing the frequency of the parallel circuit , gives an additional phase shift, compensating for the initial phase increment, due to the change in generated power. By selecting the voltage of the power source 6 and the polarity of switching on the varicap 7, it is possible to reduce the slope of the resulting phase-amplitude characteristic of the circuit with the varicap and the transistor and, thus, reduce the level of phase noise from amplitude.

Claims (1)

Invention Formula The microwave oscillator, containing a bipolar transistor, the base of which is connected to one of the first and second resistors, the other of the second of which is connected to the common bus, collector through the positive feedback circuit to the base, and the emitter to the common bus, and the first power source, while the other output of the first resistor is connected to the collector through the first length of the microstrip line, characterized in that the goal of reducing phase noise varicap is entered into it, the second segment microstrip line, the third segment microstrip line length LH4. separation capacitor, the first, second and third blocking capacitors, the third resistor and the second power source, the connection point of the first resistor and the first segment of the microstrip line connected through the third resistor to the first power source, through the first blocking capacitor to the common bus, and through the third segment of the microstrip line to the single varicap electrode, which through the second blocking capacitor is connected to the common bus; the other electrode of the varicap is connected to the second power source through the second section of the microstrip line; a capacitor is connected to a common bus, the positive feedback circuit includes a coupling capacitor, one output of which is connected to a common point of the first and second resistors, the other to 0 the junction point of the varicap and the second segment of the microstrip line, with the varicap and the second segment of the microstrip line forming a parallel. five