Patent ID: 8589470

Claim:
A down conversion filter, comprising: an input terminal; an output terminal; a charge-summing capacitor coupled between the output terminal and a common-mode terminal biased at a common-mode voltage; a first switched-capacitor circuit, comprising: a first-first sampling capacitor coupled between a first-first node and the common-mode terminal; a first-first charging switch coupled between the input terminal and the first-first node; a first-first discharging switch coupled between the first-first node and the common-mode terminal; a first-second sampling capacitor coupled between a first-second node and the common-mode terminal; a first-second charging switch coupled between the first-first node and the first-second node, wherein the first-second charging switch is turned on for charge sharing between the first-first sampling capacitor and the first-second sampling capacitor; a first-second discharging switch coupled between the first-second node and the common-mode terminal, wherein the first-second discharging switch is turned on in a phase different from a turned-on phase of the first-first discharging switch; and a first charge-summing switch coupled between the first-second node and the output terminal for charge sharing between the first-second sampling capacitor and capacitors at the output terminal; and a second switched-capacitor circuit, comprising: a second sampling capacitor coupled between a second node and the common-mode terminal; a second charging switch coupled between the input terminal and the second node; a second discharging switch coupled between the second node and the common-mode terminal; and a second charge-summing switch coupled between the second node and the output terminal.