Patent ID: 7139544

Claim:
An apparatus comprising: a mixer to convert an RF signal to a baseband-differential signal; and a transconductance-capacitor (GmC) filter to filter the baseband-differential signal, wherein the GmC filter comprises: first and second transconductance-capacitor circuits in series and a transconductance-feedback circuit in feedback with the second transconductance-capacitor circuit, wherein at least one of the first or second transconductance-capacitor circuits comprises: cross-coupled pairs of transistors to receive the baseband-differential signal and generate a differential output current; and first and second capacitors coupled respectively between differential inputs of at least one the transconductance-capacitor circuit and first and second internal-feedback nodes of at least one the transconductance-capacitor circuit, wherein the capacitors are voltage-dependent capacitors, and wherein during operation of the GmC filter, a substantially-constant bias voltage is maintained across the voltage-dependent capacitors to allow the voltage-dependent capacitors to provide a substantially constant capacitance.