Highly linear, tunable, pseudo differential transconductor circuit for the design of Gm-C filters

This paper describes the circuit level implementation of a transconductor cell that is intended to be used in open loop configuration for the design of Gm-C filters in CMOS technology. The circuit uses a fixed transconductor cascaded with a variable gain stage. The fixed transconductor is highly linear for a wide input signal swing that is close to the rails. The variable gain stage is constructed using a current mode translinear circuit. The cell is tunable to enable compensation for process, temperature, and voltage variations and to enable the adjustment of the overall filter's characteristics. The transconductor cell was designed in 0.35 /spl mu/m TSMC CMOS technology and it is intended to operate from a 2 V supply. The physical design was carried out for several cells with different transconductance. The test chip has been fabricated and it is currently under testing.