Programmable linearized CMOS OTA for fully differential continuous-time filter design

In this paper, a feedforward linearization method for programmable CMOS transconductance operational amplifier (OTA) is described. The proposed circuit technique is developed using simple source-coupled differential pair transconductors and linear reference resistor (R). As a result, an efficient linearization of a transfer characteristic of the OTA is obtained. The g_m - programmability of the developed OTA was obtained using a programmable current mirror array technique. SPICE simulations show that for 0.35 mum AMS CMOS process with a single +3 V power supply, total harmonic distortion (THD) at 1V_pp and temperature range from -30degC to +90degC is less than -35.8dB. Moreover the input voltage range of linear operation is increased. Power consumption of the linearized OTA circuit is 0.76 mW.