Crystal_oscillator_with_amplitude_modulated_output

Published:2009/7/20 23:01:00 Author:Jessie | From:SeekIC

Crystal oscillator with amplitude-modulated output. The black box crystal oscillator output is converted to DC by the AD536 PMS/DC converter. The AD536 output is summed in the AD741 with the DC reference voltage obtained by inverting and amplifying the output of the AD580 band-gap reference. The AD741 drives the 2N2222 control transistor to close the feedback loop around the oscillator by adjusting its supply voltage. The AD534 serves as an amplitude modulator. The oscilloscope waveforms show the 32.768 kHz signal being switched by a fast step from 0.3 to 2.2 volts peak to peak with no ringing, overshoot, etc. (courtesy Analog Devices, Inc.).



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