A 4.4-mA ESD-Safe 900-MHz LNA With 0.9-dB Noise Figure

A 900-MHz 1.2-V 4.36-mA low-noise amplifier (LNA) with a minimum of 0.92-dB noise figure (NF) at 868 MHz, −12-dBm IIP3, with one inductor (external) is demonstrated. The circuit achieves narrowband input matching on a wideband LNA without inductive degeneration. A new half-cascoding technique is used to improve the input matching ( $S_{11}$ ) while simultaneously achieving sub-1-dB NF performance. The 0.13- $\mu \text{m}$ CMOS LNA is fabricated with embedded electrostatic discharge (ESD) protection diodes that add 60- and 80-fF loads at the RF input and output ports. At 868 MHz, the packaged LNA has a measured input return loss ( $S_{11}$ ) of −18 dB and the transmission gain ( $S_{21}$ ) of 14.2 dB. At 900 MHz, the LNA has a measured NF of 0.98 dB. The LNA (excluding the buffer) occupies an area of 0.047 mm2. The chip passes the human body model (HBM) test with an ESD zap of 2.5 kV within 10% margin of its prezap $I$ – $V$ characteristics, under JEDEC standards. Multiple packaged chips were characterized with no perceptible difference in performance, indicating a robust design.