Abstract:
A hybrid digital phase locked loop is disclosed to recover an isochronous clock from a ''''stuffed'''' multiplexed input signal as found in an asynchronous PCM demultiplexer. A low frequency voltage controlled multivibrator is controlled by the output of a phase comparator. The phase comparator is coupled to the input signal and the output signal of a distributor. The distributor is controlled by the multivibrator to sequentially switch a multiphase output signal of a crystal oscillator to provide the output signal of the distributor. This arrangement overcomes the requirement of a voltage controlled crystal oscillator per channel group in the demultiplexer.
Abstract:
This self-oscillating clock driver circuit generates two halfsinusoidal, non-overlapping phases of output intended primarily for driving two-phase MOST circuits in a quick-step push-button dial telephone. A Hartley oscillator, modified to include an amplitude stabilization circuit, drives a pair of transistor output circuits which in turn drive the capacitive loads in a push-pull manner. The clock driver arrangement also functions as a master oscillator in the subscriber handset to provide the push-button tone frequencies.