Current tuneable CMOS transconductor for filtering applications

In this paper, a current tuneable fully differential transconductor cell (GM-C) dedicated for filtering applications is proposed. The architecture of this cell is based on a cross-coupled differential pairs input stage with folded cascode output stage in order to realise a high DC gain integrator. The resulting integrator's architecture tolerates fabricated characteristic deviations from an ideal representation and has been selected to give a simple tuneable integrator which allows the full programmability of the designed filter. Also, the realisation of a generic 4-order bandpass filter is presented with the 3.3 volts 0.35 mu m CMOS technology available through the Canadian Microelectronics Corporation (CMC). Finally, principal deviations from ideal transfer function will also be discussed in order to evaluate possible effects of the frequency response introduced by a non ideal integrator.