Differentiator based spread spectrum modulator

摘要

A spread spectrum clock generator which includes a pulse train generator circuit and a modulating circuit configured to produce a modulating signal relating to a time derivative of an output of the pulse train generator circuit. In one embodiment the modulating circuit includes a active differentiator circuit and in another embodiment the modulating circuit includes a passive differentiator circuit. A modulator is included which is configured to produce a spread spectrum clock output which is frequency modulated by the modulating signal.

主权项

1. A spread spectrum clock generator comprising:
a pulse train generator circuit configured to produce a train of pulses; a modulating circuit configured to produce, for each of the pulse train pulses, a modulating signal relating to a time derivative of the pulse, the modulating circuit including an active differentiator circuit which includes an amplifier, a feedback resistance connected between an output of the amplifier and an inverting input of the amplifier and an input capacitance connected to the inverting input of the amplifier and coupled to receive the pulse train; and a clock generator configured to produce a spread spectrum clock output which is frequency modulated by the modulating signal.