SU1749928A1 - Variable capacitor on varicaps - Google Patents

Abstract

The invention relates to radio engineering and can be used in tunable frequency selective circuits of radio electronic equipment. SUMMARY OF THE INVENTION: A variable capacitor capacitance on a vacuum circuit contains two varicaps and two capacitors. The successive inclusion of the varicap increases the quality factor of the capacitor by a factor of b. 2 Il.

Description

The invention relates to radio engineering and can be used in tunable frequency selective circuits of electronic equipment.

The purpose of the invention is to increase the quality factor of the capacitor.

Fig. 1 is a diagram of a variable capacitor (circled in dashed line) when turned on in a parallel oscillating circuit with a source of alternating voltage and load; Fig. 2 is a circuit for incorporating a variable capacitor into a series oscillating circuit.

The capacitor contains two varicaps 1 and 2 (or groups of n parallel-connected varicaps), capacitors 3 and 4 of large capacity, inductance 5, a source of alternating voltage b, resistors 7-9, capacitors 10 and 11 of large capacity.

The variable capacitor capacitance on the varicaps, included in the parallel oscillating circuit, works as follows. Control voltages equal to - to - (and En Vy) are formed

a divider on resistors 8 and 9 of the same resistance. Due to the small resistance of the coil 5, these voltages are applied to varicaps 1 and 2. When Vy changes from Ep to Vy to Uumik, the varicap control voltage varies from 0 to Ep.

In this case, the capacitance of the variable capacitor and the resonant frequency of the parallel circuit vary respectively. The capacitors 10 and 11 are separated at a constant current of the control circuit from the housing and the source 6 The first signal output is under a higher alternating voltage than the second output Otherwise a variable capacitor would have been jammed with a constant voltage source of EP and Vy. Resistors 8 and 9 for alternating current are shunted by capacitors 3 and 4 of large capacity and do not reduce the quality factor of a variable capacitor.

The capacitor connected to the serial circuit works as follows.

with

J

zom. Control voltage equal to half the difference of source voltages

2 U

(Fig. 2) -l, due to the low resistance of the coil 5 and the source of alternating voltage 6, is applied to the varicaps. With a simultaneous change of -Vy and -Vy, the capacitance of a variable capacitor also changes. The resistors 8 and 9 due to the capacitors 3 and A of large capacity are connected in alternating current parallel to the load resistor 7 and do not reduce the quality factor of the variable capacitor. The first signal output of a variable capacitor is under a higher alternating voltage than the second. Otherwise, if you switch the signal outputs opposite, the varicaps will be bridged by resistors 8 and 9. Thus, the quality factor of the variable capacitor is determined by the quality factor of the varicaps. If the quality factor of the varicaps is 200, the output resistances of the control voltage sources are 300

AT

7 ..W .. J

five

0

five

kΩ, the quality factor of this capacitor is increased 6 times.

Claims (1)

Claims A varicap variable capacitor containing two varicaps and two large capacitors, two signal leads, the first signal lead connected to the cathode of the first varicap, the anode of which is connected to the first control lead and the first plate of the first large capacitor connected to a second signal output, characterized in that, in order to increase the quality factor, the cathode of the first varicap is connected to the anode of the second varicap, the cathode of which is connected to the anode of watt Vary varicap whose cathode is connected to the second control output and the first about 4, laying of the second high-capacity capacitor, the second lining of which is connected to the second signal output. 1 L