Differential charge pump

Abstract

The present invention relates to a differential charge pump, in particular for use in a tuning system including a phase-locked loop, for generating currents, comprising a first input (IN+) and an inverse second input (IN−), in particular for receiving differential signals from a phase comparator, first current source means (Q1) for generating a first current (kIo) in accordance with the signal inputted into said first input (IN+), second current source means (Q2) for generating an inverse second current (kIo) in accordance with the signal inputted into said second input (IN−); and a first output (OUT+) and a second output (OUT−) for outputting said first and second currents, respectively. Further, the differential charge pump comprises a first controllable common mode current source means (14) for additionally feeding common mode current to said first output (OUT+), a second controllable common mode current source means (16) for additionally feeding common mode current (IBIAS2) to said second output (OUT−), and common mode controlling means (6) for controlling said first and second common mode current source means (14, 16) so as to make the common mode currents essentially equal to the currents (kIo) generated by said first and second current source means (Q1, Q2), respectively.

Dependencies are inferred from the claim text.