Noise Analysis in Switched Capacitor-Based Differential Capacitive Interfacing Circuits

This paper describes the noise analysis in switched capacitor based differential capacitive interfacing circuits for MEMS accelerometers. The interfacing circuit consists of a switched capacitor based charge amplifier, an offset nullifier, and a sample and hold circuit. The transistors and the switches in these circuits contribute the thermal and flicker noise. The theoretical analysis is carried out and compared with the simulation results. First, the noise has been calculated in each phase and then the noise simulation is performed. Finally, the periodic operating point is determined using periodic steady-state analysis and after that the periodic noise(Pnoise) simulation is compared with the previous simulation results simulated in each phase. All the simulations are carried out at the transistor level using Cadence Virtuoso.