A 50 µW, 2.1 mdeg/s/√Hz frequency-to-digital converter for frequency-output MEMS gyroscopes

Frequency-modulated operation of MEMS gyroscopes promises numerous benefits, including inherently accurate scale factor, improved bias stability, high dynamic range, and low power dissipation. An FM demodulator based on sigma-delta frequency-to-digital conversion decouples dynamic range from power dissipation to achieve a resolution of 41.1μHz in a 50 Hz bandwidth for a 30 kHz signal (2.1 mdeg/s/√Hz) with a maximum input range of 2000 deg/s while consuming 27.6μA at 1.8V. The high performance and low power consumption of this circuit enable the development of high performance, ultra-low-power, frequency-output gyroscopes and other frequency-output MEMS sensors.