On-chip stress compensation on the ZRO of a mode-matched MEMS gyroscope

Compensating the effects of external stress on a three-fold symmetric mode-matched z-axis silicon-on-insulator (SOI) MEMS gyroscope is shown to reduce long term drift for the first time. The stress sensors consist of released SOI resistors connected in a Wheatstone bridge configuration. The gyroscope is ovenized within 300 K ± 20 mK using an external heater and an on-chip temperature sensor to suppress the environmental temperature effects. The in-house vacuum packaged SOI-MEMS gyroscope is mode matched by operating both drive and sense in feedback. Allan deviation analysis of the gyroscope with on-chip stress compensation shows an order of magnitude improvement on long term stability compared to an uncompensated gyroscope.