Switching current mirror for a phase locked loop frequency synthesizer and communication device using same

摘要

A communication device (100) employs a local oscillator (104) having an improved charge pump circuit (122). The charge pump circuit (122) has current mirrors (204, 208) in which a first transistor (224, 270) is biased to provide a substantially constant current. A resistor (226, 272) selectively conducts a reference current to bias a mirror transistor (228, 274). The current mirror (204, 208) provides improved dynamic performance thereby reducing global phase error of the communication device (100).