Patent ID: 7782144

Claim:
An active filter receiving output from a first charge pump circuit and a second charge pump circuit, comprising: a first circuit component connected between output of the first charge pump circuit and a ground; a second circuit component connected between output of the second charge pump circuit and the ground; a voltage addition unit adding up voltage between both ends of the first circuit component and voltage between both ends of the second circuit component, an additional filter at a subsequent stage of the active filter, and the additional filter comprises: resistance, one terminal of which is connected to an output of the voltage addition unit; a capacity connected between another terminal of the resistance and the ground, wherein: the additional filter uses voltage between both ends of the capacity as output voltage; and a selector circuit selecting said second charge pump circuit from two charge pump circuits each of which has a different current ratio of output current relative to current from the first charge pump circuit, the active filter receives output from the first charge pump circuit and the second charge pump circuit.