An adjustable current source circuit of a phase locked loop (PLL) circuitry fabricated on a single substrate provides a first current that is a function of an error voltage proportional to an amount of a phase difference of a comparison of a reference signal and a feedback signal. The circuit includes...http://www.google.de/patents/US5332930?utm_source=gb-gplus-sharePatent US5332930 - Phase locked loop circuitry with variable gain and bandwidth
