Low noise transconductance amplifier design for continuous-time ΣΔ wideband frontend

A low-noise transconductance amplifier (LNTA) aimed at continuous-time ΣΔ wideband frontend is presented. In this application, the LNTA operates with a capacitive load to provide high linearity and sufficient Gm gain over a wide frequency band. By combination of various circuit techniques the LNTA, which is designed in 65nm CMOS, achieves in simulation the noise figure less than 1.35 dB and linearity of maximum IIP3 = 13.6 dBm over 0.8 – 5 GHz band. The maximum transconductance Gm = 11.6 mS, the return loss S11 < −14 dB while the total power consumption is 3.9 mW for 1.2 V supply.