A PLL circuit is described. The PLL circuit includes: a signal generator; and a spread spectrum modulator coupled to the signal generator, where the spread spectrum modulator receives a control voltage as an input and provides a spread spectrum control voltage to the signal generator in response to the...http://www.google.de/patents/US20030160641?utm_source=gb-gplus-sharePatent US20030160641 - Analog implementation of spread spectrum frequency modulation in a programmable phase locked loop (PLL) system
