Dynamic matching of up and down currents in charge pumps to reduce spurious tones

摘要

A device in a phase-locked loop circuit that dynamically matches the currents in a charge pump to reduce the spurious tones during each charge pump event when the phase-locked loop is in lock. A regulator circuit is coupled to a first current source in a charge pump and is responsive to inverted up and down signals from a phase detector or to the currents of a charge pump. The integrator may adjust the first current to equal the second current when inverted up and down signals do not arrive at the regulator at the same time or when the loop filter voltage does not match the charge pump output voltage with both current sources of the charge pump are turned on but disconnected from the loop filter.