An Impedance-boosted Switched-capacitor Low-noise Amplifier Achieving 0.4 NEF

This paper presents an impedance-boosted analog front-end (AFE) for mm-scale ultra-low power sensor nodes. The proposed AFE employs a discrete-time low noise amplifier (LNA) based on noise-efficient switched-capacitor stages. The input impedance, ZIN, is boosted through a 27-step multiphase soft-charging technique of the bottom-plate capaci-tance, achieving ZIN > 10 MΩ at 4.5 MHz sampling frequency. The LNA achieves 0.4 NEF and 0.15 PEF, the smallest values reported to date, while consuming 0.28 μW.