CMOS operational transconductance amplifier

Abstract. In the paper, a feedforward linearization method for differential-pair operational transconductance amplifier (OTA) is discussed. The proposed technique is developed using simple differential pair transconductors and linear reference resistor. The concept leads not only to very efficient linearization of a transfer characteristic of the OTA but also offers the possibility of effective phase compensation. Due to this, the circuit can be used in applications requiring precise phase response (e.g. filters). SPICE simulations show that for the circuit working with a ±1.25V power supply, total harmonic distortion (THD) at 0.8Vpp is less then 0.1 % in comparison to 10.2 % without linearization. Moreover, the input voltage range of linear operation is increased. Power consumption of the overall circuit is 0.94mW. The 3rd order elliptic filter example has been designed and simulated. It turns out that the proposed compensation scheme significantly improves the performance of the filter at higher frequencies