Patent ID: 7224213

Claim:
A switched-capacitor ripple-smoothing filter, comprising: a positive input node (e.g., P) operable to receive an input signal; a negative input node (e.g., N) operable to receive an input signal; a first pair of capacitors (e.g., Ce and Co) at a first pair of intermediate nodes (e.g., A 1 and A 2 ) coupled through a first pair of associated switches (e.g., 411 , 412 ) to the positive input node, the switches operable to alternately open and close to enable the associated capacitors to sample the input signal on the positive input node; a second pair of capacitors (e.g., Ce and Co) at a second pair of intermediate nodes (e.g., A 3 and A 4 ) coupled through a second pair of associated switches ( 413 , 414 ) to the negative input node, the switches operable to alternately open and close to enable the associated capacitors to sample the input signal on the negative input node; a positive output node (e.g., Voutp) coupled to the first pair of intermediate nodes; a negative output node (e.g., Voutn) coupled to the second pair of intermediate nodes; and an offset cancellation circuit having a first pan (e.g., capacitors 429 and 443 ) coupled between the first pair of intermediate nodes and the negative output node and a second part (e.g., capacitors 434 and 452 ) coupled between the second pair of intermediate nodes and the positive output node, the offset cancellation circuit operable to cancel at the output nodes offset voltages that appear at the intermediate nodes.