Patent ID: 7800445

Claim:
A trans-conductance cell comprising: a positive voltage rail for providing a positive power supply voltage; a negative voltage rail for providing a negative voltage power supply voltage; a pair of voltage inputs, one inverting and one non-inverting, for developing a differential voltage input signal having a common mode voltage range from one of the rail voltages to within a volt or less of the other rail voltage; and a pair of cross-coupled transconductor circuits, each transconductor circuit including: i. a source voltage follower responsive to one of the voltage inputs for sourcing relatively unbounded output current at unity voltage gain, ii. a sink voltage follower responsive to the other voltage input for sinking relatively unbounded output current to a current output terminal, and a transconductance resistor connected between the source voltage follower and the sink voltage follower for developing a differential output current proportional to the differential voltage input signal; iii. whereby transconductance of the cell is substantially constant over the range of the differential voltage input signal without limiting the differential output current.