A high-frequency CMOS linear transconductance element

A simple four-transistor, linear, tunable, high-frequency transconductance element is described. By using a pair of composite
n
-channel-
p
-channel devices, the circuit achieves its linearity by current differencing without undue matching requirements. It is shown that linearity and frequency response can be optimized simultaneously by appropriate choice of device dimensions. The performance is verified by SPICE simulations, and an operational transconductance amplifier (OTA) is used as one example for the many applications of the proposed element.