A monolithic phase locked loop for data communications. The IC contains a basic phase locked loop for tracking an input signal within the pass band, a quadrature phase detector which provided carrier detector and an FSK voltage comparator which provides FSK demodulation.
In the circuit shown, the IC is used as an FSK demodulator such as would be found in the receiver circuit of a modem. The table below shows the component values required for a modem demodulator using standard European tones on the public switched network.
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