Low voltage highly linear tunable BiCMOS OTA using parasitic vertical bipolar transistor in CMOS technology

A low distortion low voltage BiCMOS tunable OTA with a very wide transconductance (gm) adjustment , and a wide input range is presented. Input transconductance transistors operate in triode region. The main feature of the proposed BiCMOS OTA are, it can operate at low voltage single supply 1.8 V, gm tuned linearly with a tunable voltage for a wide range (0 V to 1 V). Total harmonic distortion (THD) is less than -43 dB for input voltage 0.8 V_pp and frequency 50 KHz, and the OTA can be implemented in BiCMOS technology or standard CMOS technology using a vertical bipolar transistor. The OTA simulated using PSPICE program and 0.18 ¿m CMOS technology.