High Linearity BiCMOS Multiplier/Transconductor Structures

A new wide-input range BiCMOS analog multiplier is proposed based on the triode and saturation region operation of the MOS transistors. The new circuit can also be reconfigured to operate as a versatile Operational Transconductance Amplifier, OTA, with independent current bias control for N stages. The novel design involves the use of attenuators at the input stage to boost the input linear range. It also utilizes a high output impedance subtractor setup at the output stage to obtain a single-ended output. The new circuit is characterized by its large input range, its high linearity and ability to operate at low voltages as well as high frequencies. HSPICE simulation results of the circuit, using the MOSIS 2 μm process parameters, resulted in an input range of ± 4 V (± 5 V supply), ± 1.9 V (± 3 V supply) and ± 1 V (± 2 V supply), with linearity error less than 0.5%. It's usages in certain analog signal processing applications are also discussed.