A Continuous-Time Collocated Force-Feedback and Readout Front-End for MEM Gyroscopes

A front-end circuit for closed loop continuous-time delta-sigma (CT ΔΣ) micro-electro-mechanical gyroscope readout circuits is implemented. This work presents for the first time a CT collocated feedback, which simultaneously uses the detection capacitors of the sensor for the signal readout and the feedback. This is realized by the modulation of the input common mode of the readout amplifier and relies solely on CT techniques to achieve a low noise floor. Additionally, the concept decreases the number and the complexity of the signals in the high voltage (HV) domain. Therefore, the power and area demands of the developed HV interface for quadrature compensation and mode matching are reduced. The circuit is implemented in a 0.35 μm technology, requires an area of 0.65 mm² and consumes 770 μW.