Waveform Generator

A waveform generator is versatile instrument that delivers a choice of different waveforms whose frequencies are adjustable over a wide range. The most common output waveforms are the Sine, Triangular, and saw tooth waves. The frequencies of these waveforms may be adjusted from a fraction of a Hertz to several hundred KHertz.  The waveform generator can supply output waveforms at very low frequencies. This instrument delivers waves with a frequency range of 0.01Hz to 100 KHz. Figure shows the block diagram of waveform generator.


The frequency control voltage regulates two current sources. The upper current source supplies a constant current to the triangular integrator whose output voltage increases linearly with time. An increase or a decrease in the current supplied by the upper current source increases or decrease the slope of the output voltage. The voltage comparator multivibrator changes state at a predetermined level on the positive slope of the integrators output voltage.  These change of state cuts off the upper current supply to the integrator and switches on the lower current supply. The lower current source supplies the reverse current to the integrator so that its output decreases linearly with time. When the output voltage reaches a predetermined level on the negative slope the output waveform, the voltage comparator again switch and cuts off the lower current source while at the same time switching on the upper source again.

The voltage at the output of the integrator has a triangular  waveform whose frequency is determined by the magnitude of the current supplied by the constant current sources. The comparator delivers a square wave output voltage of the same frequency. The third output waveform is derived from the triangular waveform which is synthesized into a Sine wave by a diode resistance network. In this circuit the slope of the triangular wave is altered as its amplitude changes, resulting in a Sine wave with less than 1% distortion. The output circuitry of the function generator consist of two output amplifiers that provide two simultaneous, individually selected outputs of any of waveform functions. It is a device which generates various signals (functions) like sine, Square triangular wave. It has different frequency slots ranging from 0MHz to 1MHz.

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