| 摘要 |
A power conserving phase-locked loop achieves power savings by adding a switch which selectively enables the bias current for the charge pump associated with the phase comparator of the phase-locked loop. The switch is connected by a logic circuit to a counter that tracks the expected arrival time of a signal edge of the reference signal. Immediately prior to the arrival of the expected signal edge, the switch is enabled, thereby creating and applying the bias current to activate the charge pump in the event that a correction is needed to maintain the "lock" in the phase-locked loop. When the signal edge passes, the bias current is turned off again before the arrival of the next signal edge. This switching may result in a ten percent duty cycle in the biasing current, resulting in approximately a ninety percent power savings. The phase-locked loop may be used for a variety of applications, such as a frequency synthesizer in a receiver chain of wireless communications mobile terminals, where power consumption is a concern. |
