Pseudo-Continuous-Time Readout Circuit for a 300^∘/s Capacitive 2-Axis Micro-Gyroscope

The interface for a capacitive 2-axis micro-gyroscope is implemented in a 0.35-¿m HVCMOS technology with an active area of 2.5 mm2. Compared to a regular continuous-time interface with large on-chip RC time constants, the reduction of the chip area is made possible by the pseudo-continuous-time readout technique, of which a detailed analysis is presented in this paper. The technique allows a dc biasing voltage to be used for the detection and does not require any large RC time constants to be implemented. For the sensor that was implemented the x- and y axis noise floors are 0.015°/s/¿Hz and 0.041°/s/¿Hz . The supply current and voltage for the chip, including the charge pump and the drive and sense interfaces, are 1.8 mA and 2.5-3.6 V, respectively. The supply current of a single sense readout channel is approximately 0.4 mA.