Toric Limited

University of Surrey

Michael James Underhill

Neil Alexander Downie

An anti-jitter circuit has an integrator storage capacitor. A charge pump derives from an input pulse train at least one charge packet during each cycle of the input pulse train and supplies the charge packets to the storage capacitor. A controlled current sink operating in conjunction with a high impedance low pass filter continuously discharges the storage capacitor to create a sawtooth voltage waveform having a mean d.c. voltage level. A differential comparator compares the sawtooth voltage waveform with the mean d.c. voltage level and the comparator output is used to trigger a monostable circuit to generate an output pulse train having reduced time jitter

Anti-jitter circuits

A noise reduction circuit useful as a clock restoration circuit includes a DC removal circuit for removing a DC level from an input pulse train, an integrator for integrating the input pulse train after a DC level has been removed, a comparator for comparing the integrator output with a threshold value (V ) to detect for a missing pulse, a pulse generator inserting into the input pulse train an additional pulse delayed with respect to any missing pulse, and an output circuit for generating an output pulse train from the integrator output.

Noise reduction circuits

A phase noise reduction circuit for reducing phase noise in an input pulse train consisting of pulses which are all of the same length and which, in the absence of phase noise, have a nominal frequency f, includes a DC removal circuit for removing a DC level from the input pulse train, an integrator for integrating the input pulse train after a DC level has been removed therefrom by the DC removal circuit and a comparator for deriving from the integrated pulse train an output pulse train containing periodic transitions at said nominal frequency. The input pulse train may be derived using a monostable circuit.

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Lingfield, United Kingdom

Michael James Underhill