Setting the common mode level of a differential charge pump output

摘要

An embodiment of the invention is directed to a circuit including first and second filter nodes for being connected to a filter and first and second bypass nodes corresponding to the first and second filter nodes, respectively. A charge transfer circuit having at least one charge transfer node is to be alternatively coupled to one of the filter nodes and a corresponding one of the bypass nodes for transferring charge to control a differential voltage of the filter nodes. First and second amplifiers are to buffer the voltages on the first and second filter nodes at first and second outputs which are coupled to the first and second bypass nodes, respectively. The output voltage of each amplifier can be adjusted according to a difference between a control voltage and a common mode voltage of the first and second nodes.