A Compact 0.1–1.95 GHz, 1.5 dB NF LNTA Based on Cascode Inverters

This brief describes the design and characteristics of a wideband low-noise transconductance amplifier (LNTA) based on cascode inverter cells for use in surface acoustic wave (SAW) filter-less receivers (RXs). Compared to conventional low-noise amplifiers (LNAs), LNTAs offer superior linearity as they process signals in the current mode. A novel derivative superposition (DS) method is introduced to enhance the third-order input intercept point (IIP3), and the noise canceling (NC) technique is employed to overcome the inherent trade-off between noise figure (NF) and wideband input impedance matching. The circuit design process is accelerated using Bayesian optimization. Furthermore, the NF and IIP3 of the LNTA can be tuned by adjusting the input bias voltage. The chip is fabricated using 40-nm low-power (LP) CMOS technology. Experimental results demonstrate that the S11 is lower than -10 dB in the frequency range of 0.1-1.95 GHz, with a maximum transconductance gain of 126 mS and a minimum NF of 1.5 dB. The average IIP3 and output 1 dB compression point (OP1dB) over the frequency band is 4 dBm and 1.6 dBm, respectively. The blocker NF is 4.25 dB under a -15 dBm blocker and the blocker P1dB is -19.9 dBm. The power dissipation is 22 mW at a 1.25 V supply. Notably, the chip occupies only 0.0032 mm2 without on-chip inductors and capacitors.