A charge pump circuit suitable for use in a high frequency phase locked loop. The charge pump circuit comprises a biasing circuit, a charging transistor, a discharging transistor, and a pair of complementary switches. The charging transistor may be a p-channel field effect transistor (FET), and the discharging...http://www.google.com/patents/US5532636?utm_source=gb-gplus-sharePatent US5532636 - Source-switched charge pump circuit
