A Compact Bidirectional Pseudo Floating Gate Front-End for Resonating Sensors based on NAND and NOR logic Gates

In this paper we present an alternative method to realize a compact bidirectional Front-End for resonating sensors based on Ring Down Method (RDM) and pseudo floating gate amplifier (PFGA). This goal is achieved by using the voltage buffer inside the PFGA for both biasing of the amplifier and actuation of the sensor. The proposed analog front-end doesn't require any coupling capacitor, minimizing the area occupied by the circuit. Simulations in AMS-350nm CMOS technology with a power supply of 3.3V and measurements on a prototype implemented with discrete components have been used to verify the correct operation of the system. The Front-end was realized by using the integrated circuits (ICs) CD4007UBE and ALD1103, and tested with a real piezoelectric transducer (MURATA MA40S4R), characterized by a resonant frequency of 40kHz. Measurement and simulation results show that the proposed circuit is a good candidate to realize a compact and bidirectional pseudo floating gate front-end, which resembles the circuit of NAND and NOR logic gates.