SU1663742A1 - Controlled rc generator - Google Patents

Abstract

The invention relates to radio engineering. The purpose of the invention is to increase the frequency stability of the output signal. The RC generator contains an operational amplifier (OA) 1, circuit 2, first and second electronically controlled switches (EC) 3, 11, variable resistor (PR) 4, first and second capacitors (K) 5, 6, driver (F) 7, filter (LPF) 8, amplitude detector 9, trigger (T) 10. From the output of F 7, a sequence of pulses through T 10 goes to the control inputs of the first and second ECU 3, 11. PR 4 and the first and second K 5, 6 are elements of the frequency-supply chain. The detector 9 together with the circuit 2 provides stabilization of the amplitude of the output oscillations. The low-pass filter 8 excludes components that are multiples of the frequency f 7 in the spectrum of the output sinusoidal signal. 1 Il.

Description

ON ABOUT vj

The invention relates to radio engineering and can be used as a source of electrical oscillations.

The purpose of the invention is to increase frequency stability without increasing the level of non-linear distortion of the output signal.

The drawing shows the structural electrical circuit of the controlled RC-repeater.

The controlled RC generator contains an operational amplifier 1, a circuit 2 of frequency-independent feedback, a first electronically controlled switch 3, a variable resistor 4 "first and second capacitors 5 and 6, a driver 7 for controlling pulses, a low-pass filter 8, the amplitude detector 9, the trigger 10, the second electronically controlled switch 11, and the driver 7 can be performed on the generator of triangular pulses 12 and the voltage comparator 13.

The controlled RC generator operates as follows.

After power is applied and the pulse sequence 7 appears at the output of the pulse generator 7, the first electronically controlled switch 3 and the second electronically controlled switch 11 periodically switch, due to the fact that a sequence of pulses from the trigger output 10 is fed to the control input of the first electronically controlled switch 3 , their duty cycle is equal to two and does not depend on the pulse duty cycle, which are fed to the input of the trigger 10 and the control input of the second electronically controlled switch yuchatel 11. The output signal of the operational amplifier 1 sinuso- idalnoy form is input to the amplitude detector 9, and its output has a DC voltage proportional to the amplitude of the sine wave is supplied to an input of a 7 liter emoy controlled porosity. Depending on the magnitude of the DC voltage applied at the input of the driver 7, a sequence of pulses with a proportional duty cycle appears at its output, which, applied to the control input of the second electronically controlled switch 11, changes in the positive feedback circuit b of the operational amplifier 1 is the transmission coefficient, which leads to the stabilization of the amplitude of oscillations at the output of the controlled RC-repeater.

As a result of such work of the first and second electronically controlled switches 3 and 11, the frequency fr at the output of the controlled RC generator is determined by the formula

eleven

fr

4l: / s 1 C2

 KQ,

where R is the resistance of the variable resistor 4,

Ci, Ca are the capacitances of the first 5 and second 6 capacitors, and does not depend on the duty ratio of the control pulses.

The amplitude balance condition is determined by the formula

2С2 С

where K is the transmission coefficient of the frequency-independent feedback circuit 2,

Q is the duty cycle of the pulses at the output of the imager 7.

The imaging unit 7 may contain a generator of 12 triangular pulses and a comparator 13. Comparing two signals (12 triangular pulses from the generator output and an amplitude detector 9 output), a sequence of pulses is formed at the output of the comparator 13 with a proportionality proportional to a constant voltage 9.

Filter 8 excludes components in the output spectrum that are multiples of the frequency of the driver 7. The amplitude stability of the output oscillations can be increased if the input of the amplitude detector 9 is connected not to the output of the operational amplifier 1, but to the output of the filter 8.

Claims (1)

Invention Formula A controlled RC oscillator containing an operational amplifier, a frequency-independent feedback circuit that is connected between the output and the inverting input of the operational amplifier, the first electronically controlled switch, the first and second inputs of which are connected, respectively, to the non-inverting input of the operational amplifier and the common bus, serially connected variable resistor and the first capacitor, the second output of which is connected to the input of the first electronically controlled switch, the second capacitor, which connected between the non-inverting input of the operational amplifier and the common bus, the control pulse driver, the amplitude detector, which is connected between the output of the operational amplifier and the control input of the control pulse generator, a low-pass filter, whose input is connected to the output an operational amplifier, and the output is an output of a controlled RC generator, characterized in that, in order to increase frequency stability without increasing the level of nonlinear distortion of the output signal, a trigger and a second electronically controlled switch, the first and second outputs of which are connected respectively, are introduced into it to the common bus and the second output of the variable resistor, the input of the second electronically controlled switch is connected to the output of the operational amplifier, and the trigger is connected between the output of the control pulse generator and the control input of the first electronically controlled switch, the output of the control pulse generator is connected to the control input of the second electronically controlled switch.