Novel low-voltage CMOS biquads

Novel low-voltage CMOS biquads that operate in voltage-mode and current-mode are presented. They are implemented using single-output or triple-output operational transconductance amplifiers (OTAs) and capacitors. The new CMOS realization of the OTA is based on the cross-coupled configuration and is biased by the common-mode voltage. With only two transistors stacked between the supply rail and ground, the proposed OTA is well suitable for low-voltage applications. Simulation results show that the biquads realized by the proposed OTA have the advantages of low-voltage operation, simple circuitry, multiple filtering functions and electronic tunability (ω₀ and Q)