Patent ID: 8193868

Claim:
A switched capacitor circuit for use at at least one operating frequency, the switched capacitor circuit comprising: an inductive element having a first terminal and a second terminal, wherein the first terminal is coupled to receive a switching voltage; a hetero-junction bipolar transistor (HBT) having a base terminal, a first conducting terminal, and a second conducting terminal, wherein the base terminal of the HBT is coupled to the second terminal of the inductive element, and wherein the second conducting terminal of the HBT is coupled to a voltage supply terminal; and a capacitor having a first terminal and a second terminal, wherein the first terminal of the capacitor is coupled to the first conducting terminal of the HBT and the second terminal of the capacitor is coupled to a node, wherein a capacitance value at the node is a function of the switching voltage, the inductive element is configured such that a combined impedance of an impedance of the capacitor, an impedance of the HBT, and an impedance of inductive element resonates at the at least one operating frequency only when the HBT is substantially non-conducting, and the node is coupled to a variable capacitor such that the variable capacitor is in parallel to the capacitor.