CMOS transconductance element

A cross-coupled, ratioed quad cell was described by Nedungad, and Viswanathan [1]. One useful property of the quad is that it enables a linear large-signal transconductance cell. The other property that can be exploited is that it gives an output current proportional to the square of a differential input signal. A negative-feedback technique which eliminates the need for ratioing transistors and achieves the same objectives using matched transistors is described. Simulation results are given to show the linearity that can be obtained as well as to indicate the frequency range over which these transconductance elements can be employed for filtering applications of continuous-time signals.