High accuracy temperature-compensated piezoresistive position sensing system

A microelectromechanical system, MEMS, comprising:

• a substrate;
• a plurality of MEMS elements supported from the substrate;
• a control system arranged to receive a control signal and to generate one or more actuator control signals;
• and
• for each MEMS element of the plurality of MEMS elements,
• (i) one or more piezoelectric actuators, each piezoelectric actuator is arranged to receive at least one of the actuator control signals and accordingly displace the corresponding MEMS element relative to the substrate,
• (ii) at least one piezoresistor sensing element for generating an analogue sensor signal indicative of displacement of the MEMS element, and
• (iii) a temperature sensor for generating an analogue temperature signal indicative of the temperature of the piezoresistor sensing element;
• wherein the control system is configured to:
• (i) use the analogue sensor signals and the analogue temperature signals respectively to generate corresponding digital sensor signals and corresponding digital temperature signals,
• (ii) calculate target actuator control voltages using the received control signal, the digital sensor signals and digital temperature signals;
• whereby calculating the target actuator control voltages includes calculating an estimated strain in the temperature sensor, and correcting a temperature value indicated by the temperature signal for dependence on strain in the temperature sensor using the estimated strain;
• and
• (iii) to generate the actuator control signals based on the calculated target actuator control voltages.