Voltage-controlled broadband sine-wave oscillator

Abstract

A wide-band voltage-controlled sine wave oscillator, the stable oscillation amplitude is a photoresistor R F , through the optocoupler, R F The resistance value is automatically adjusted by the amplitude control circuit; the oscillation frequency is controlled by two photoresistors R S and R P , through the optocoupler, R S and R P The resistance value is controlled by the frequency control circuit to realize that the oscillation frequency varies with the external control voltage V C And variable, with the frequency range of up to thousands of times, and the characteristics of small waveform distortion, simple and practical circuit structure, low cost. Embodiments include a broadband low-distortion sine wave / square wave signal generator, a frequency sweeper, a sine wave frequency synthesizer, and phase synchronization of signals. Can be used for electronic experiments and teaching.

Description

1. Technical field [0001] The invention relates to a wide-band voltage-controlled sine wave oscillator. 2. Background technology [0002] In the prior art, it is difficult to realize a sine wave oscillator with wide frequency band and undistorted waveform. The few RC voltage-controlled sine wave oscillator integrated circuits XR2206 and ICL8038 use the integral-trigger type, which first generates a positive triangle wave and then converts it into a sine wave. Due to the limitation of the conversion technology, it can be seen that the waveform is still somewhat distorted in a wide frequency range. . German patent DE3711671 describes an all-pass oscillator with an amplitude stabilizing circuit, that is, a broadband RC sine wave oscillator, and its circuit structure is complex. Japanese patent JPO8274636 describes an RC voltage-controlled sine wave oscillator used in a frequency synthesizer, which is a positive feedback amplification type with a loop gain of 1 and a phase shi...

AI Technical Summary

Problems solved by technology

[0002] In the prior art, it is still difficult to realize a sine wave oscillator with a wide frequency band and undistorted waveform

The few RC voltage-controlled sine wave oscillator integrated circuits XR2206 and ICL8038 use the integral-trigger type, which first generates a positive triangle wave and then converts it into a sine wave. Due to the limitation of the conversion technology, it can be seen that the waveform is still somewhat distorted in a wide frequency range.

German patent DE3711671 describes an all-pass oscillator with a stable amplitude circuit, that is, a wide-band RC sine wave oscillator, and its circuit structure is complex

Japanese patent JPO8274636 describes an RC voltage-controlled sine wave oscillator used in a frequency synthesizer, which is a positive feedback amplification type with a loop gain of 1 and a phase shift of zero. This patent only uses field effects in the hysteresis phase shifting circuit The tube is used as a voltage-controlled variable resistor, and it is difficult to match the potential in the advanced phase-shift circuit and is useless

Experiments have shown that if the resistance and capacitance values ​​in the lead and lag circuits are not equal, the waveform distortion will increase significantly, because the total phase displacement cannot be eliminated to zero

Due to the aging of components and changes in ambient temperature, if there is no amplitude stabilization circuit, even if it is as simple as a point frequency, it is difficult to maintain the loop gain at 1, resulting in vibration stop or waveform clipping

Amplitude-stabilizing components use the heat-sensitive effect of small tungsten lamps, which can be regarded as linear resistance in one oscillation cycle, so the distortion is small, but the source of power consumption is large; there are diodes and Zener diodes, which are easy to manufacture, but Its resistance value changes non-linearly during an oscillation cycle, which easily leads to local distortion of the waveform

Images