Avoiding common-mode feedback in continuous-time g/sub m/-C filters by use of lossy integrators

A method of continuous-time fully-differential signal processing is proposed which avoids the use of common-mode feedback (CMF) circuitry. Instead, the DC output voltage of the transconductor (G/sub M/) is defined by a 1/g/sub m/ resistor load and by implementing a precise biasing scheme to control the DC output voltage with accuracy similar to that of a good CMF circuit. The approach results in single-ended cascade filters built around a single-ended double-input CMOS triode-region G/sub M/. Fully differential filters are obtained by connecting two such single-ended structures in parallel and driving them with differential signals. The advantages of the discussed method result in systems with improved stability, and reduced noise, distortion, power consumption and the area.