An RF MEMS Sensor Driver/Readout SoC with Resonant Frequency Shift and Closed-Loop Envelope Regulation for Microplastic Detection

This paper presents a high-precision RF MEMS sensor driver and readout SoC to implement a low-cost portable device for microplastic (MP) detection. The proposed sensor driver and readout SoC operate as a miniaturized RF signal generator and network analyzer, respectively, that can analyze the resonant frequency shift depending on MP concentration. The system also adopts the closed-loop power amplifier (PA) envelope regulation to ensure consistent sensor driving against frequency shift. The 180-nm CMOS sensor driver chip exhibits an output power up to 0.23 dBm at 1.14 GHz and achieves small output power variation of4.9% between 1.1 GHz and 1.15 GHz, compared to 12.6% of the conventional drivers, thanks to PA envelope regulation. The 250-nm CMOS readout SoC can sense a minimum -10dBm input power and detect the changes of the input power with the dynamic range of18 dB, achieving a small linearity error of 1%.