| 摘要 |
<p>A phase-locked loop comprises a charge pump controlled by a one-shot pulse and a comparator output pulse. From a first voltage (132), first and second currents are generated. The first current (134) is transformed into a third current (140) by changing the polarity of the first current using a current minor (110). A first output pulse (148) is generated in response to the comparator output pulse (44) and the third current and a second output pulse (184) is generated in response to the one-shot pulse (52) and the second current (136). The first and second output pulses (148,184) are added to create a charge pump output signal used to adjust the phase-locked loop. The phase-locked loop is locked onto a frequency when the first and second output pulses are approximately equal such that they cancel when added. Creating the first and second currents from the same first voltage (132) creates equal noise components in the first and the second currents (134,136) such that the noise components cancel when the second and third currents (136,140) are added creating a charge pump output signal with reduced noise.</p> |
