Patent ID: 7339418

Claim:
A differential filter comprising: a differential operational amplifier (op-amp); a first RC network configured to couple between a first input terminal and a first output terminal of the op-amp; a second RC network configured to couple between a second input terminal and a second output terminal of the op-amp; a first resistive element configured to couple to the first input terminal of the op-amp; a second resistive element configured to couple to the second input terminal of the op-amp; a first capacitive element configured to couple between a midpoint of the first resistive element and the second output terminal of the op-amp; a second capacitive element configured to couple between a midpoint of the second resistive element and the first output terminal of the op-amp; and a first transistor having a control terminal, an input terminal, and an output terminal, wherein the input terminal of the first transistor is configured to couple to the first output terminal of the op-amp, wherein the output terminal of the first transistor is configured to couple to the first input terminal of the op-amp, and wherein the first transistor is operable to disable the first output terminal of the op-amp in response to a control signal being applied to the control terminal of the first transistor to disconnect the differential filter; wherein the first capacitive element and the second capacitive element enable a second-order response of the differential filter.