OTA linearity enhancement technique for high frequency applications with IM3 below -65 dB

A technique to enhance the linearity of continuous-time operational transconductance amplifiers (OTA)-C filters working at high frequencies is proposed. Each OTA consumes 10.5 mW and the transconductance can be tuned from 70 to 160 μA/V while the IM3 remains below -70 dB up to 50 MHz for a 1.3-V_pp differential input. For a 20-MHz low-pass second-order filter implementation, the measured IM3 with an input voltage of 1.3 V_pp is below - 65 dB. The supply voltage is 3.3 V. Experimental results of the circuit, fabricated in a standard CMOS 0.35-μm technology, are presented.