A Robust Voltage and Current Stabilization Method for Ultra-Low Voltage Low-Power Inverter-Based RF LNTAs

Ultra-low voltage inverter-based low-noise transconductance amplifiers (LNTA) are used for the implementation of energy-efficient short-range RF receivers due to their high equivalent gm/ID ratio. However, they are very sensitive to process, voltage and temperature (PVT) variations, so active biasing circuits are required for proper operation. In this paper, a novel method based on forward bulk biasing is presented to compensate for the variability of the output voltage and drained current of an inverter-based LNTA implementation without the need for a stacked control transistor. To demonstrate the effectiveness of the proposed method, an LNTA was developed in a 65 nm CMOS process with low-VT deep-nwell transistors operating at a supply voltage of 0.4 V in the 2.4 GHz ISM band. Post-layout simulations resulted in a power dissipation of 235 μW, a noise figure of 3.17 dB, avoltage gain of 12.6 dB and a silicon area of 0.11 mm2. The execution of a 1,000-run post-layout Monte Carlo analysis hasshown that the proposed biasing method drastically reduces the sensitivity to process variability even considering thesupply voltage variation of ±10% and a temperature range of -40°C to 100°C.