System-Theoretical Analysis of Analog-CDMA Applied to Mixed-Signal Readout Interfaces for MEMS Gyroscopes

Conference: PRIME 2012 - 8th Conference on Ph.D. Research in Microelectronics & Electronics
06/12/2012 - 06/15/2012 at Aachen, Germany

Proceedings: PRIME 2012

Pages: 4Language: englishTyp: PDF

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Giomi, Edoardo; Fanucci, Luca (Dept. of Information Engineering, University of Pisa, Via Diotisalvi 2, 56122 Pisa, Italy)
Rocchi, Alessandro (SensorDynamics AG, via Mario Giuntini 13, 56023 Navacchio (Pisa), Italy)

This paper presents a novel architecture for low noise mixed-signal readout systems for 3-axes micromachined gyroscopes; the proposed solution experiments an innovative readout technique based on analog-CDMA (Code Division Multiple Access) in order to extremely simplify the analog front-end which can be based on a single charge amplifier. Many family codes have been considered in order to find the best solution between performance and complexity. As a result, Walsh codes have been finally selected. Simulations prove the effectiveness of this technique in processing all the required gyro signals: the three sensing signals and one primary signal for keeping the sensor in resonance. The proposed solution can achieve good reduction of silicon area and current consumption in the analog section with reference to other multiplexing schemes. Keywords- CDMA, capacitive gyroscope, mixed-signal readout interfaces, MEMS, analog front-end, Walsh codes