Highly linear OTA with 3rd-order nonlinearity superposition techniques for Gm-C low-pass filter with 34dBm IIP3

A highly linear operational trans-conductance amplifier (OTA) with 3
^rd
-order nonlinearity superposition technique is proposed. For achieving high linearity, a native threshold voltage NMOS working in linear region is utilized to obtain the positive 3
^rd
-order nonlinear form to compensate the negative 3
^rd
-order nonlinear form generated by a normal threshold voltage NMOS which is also working in linear region. Based on the proposed highly linear OTA with 42dBm OIP3, a 4
^th
-order butterworth G
_m
-C low-pass filter with a tunable cut-off frequency from 1MHz to 10MHz is demonstrated in a standard 0.13μm CMOS technology. The filter achieves 34dBm in-band IIP3, consumes 9.9mW from 1.2V supply voltage, and occupies 0.62mm
²
silicon area.