DIGITAL_SINE_WAVE_GENERATOR

Published:2009/6/24 22:26:00 Author:May | From:SeekIC

The sine-wave generator starts with an 8-MHz signal and divides it by eight to obtain 1 MHz at C1 (IC1's 2-MHz and 500-kHz outputs can serve as alternate drive signals). Qllevel-shifts the 1-MHz pulses so that they can drive the bipolar circuitry necessary for producing a bipolar output. Syn-chronous counter IC2 divides 1 MHz by 256 to give the desired output frequency (3906 Hz), and IC3 filters the harmonic frequencies.The filter's clock is taken from the first divide-by-2 tap of IC2 to assure a 50% duty cycle. IC2 fur-ther divides this signal by 128 to ensure that the filter's input signal (1 MHz/256) falls within the flat portion of the filter response.The output of the switched-capacitor filter resembles a sampled sine wave. It can be smoothed by building a first- or second-order low-pass filter around the otherwise uncommitted output op amp.



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