Patent ID: 6792062
Filing Date: 2004-09-14
Classification: H03F,H03L

Abstract:
Differential charge pump with integrated common-mode control circuitry (100) for a phase-locked loop, comprising:a charge pump section (103) having a first signal output (OUT+) and a second signal output (OUTâˆ’); current generating means (111, 112, 113, 114) for generating a first current signal having a first magnitude and a certain polarity on said first signal output (OUT+), and for generating a second current signal having a second magnitude and opposite polarity on said second signal output (OUTâˆ’); and a common-mode feedback section (106), comprising: sensing means (121) for sensing the common-mode voltage level (VCM) of said first and second signal outputs (OUT+, OUTâˆ’); comparing means (122) for comparing said common mode voltage (VCM) of said two signal outputs with a reference voltage (VSET); and controllable means (124, 125, 126, 127) controlled by said comparing means (122) for increasing the first magnitude of the first current signal and simultaneously decreasing the second magnitude of the second current signal, or decreasing the first magnitude of the first current signal and simultaneously increasing the second magnitude of the second current signal, respectively, in response to control signal generated by said comparing means (122) based on the result of said comparison.