Wideband microwave OTA with tunable transconductance using feedforward regulation and an active inductor load

A microwave operational transconductance amplifier (OTA) using a feedforward-regulated cascode stage and an active inductor load is proposed in this paper. The use of the feedforward regulation mechanism provides the OTA with a very wide bandwidth of over 10 GHz while the active inductor load contributes to the OTA's high linearity performance. Furthermore, the transconductance of the OTA can be varied from 5 mS to 20 mS. The OTA is designed in a 0.13-μm CMOS technology and it draws a maximum of 5.5 mA of current from a 1.2 V supply when the transconductance is set to 20 mS. The chip occupies an area of 110 μm × 66 μm.