SYNCHRONOUS TIMING TO MEMS RESONANT FREQUENCY

A signal processing system (100) for a vibrating structure angular rate sensor (101) having a vibrating structure (102) and primary drive (103) and pickoff (105) transducers for causing the vibrating structure angular rate sensor to oscillate at a resonant frequency, for detecting oscillation of the vibrating structure angular rate sensor (101). The signal processing system comprises a digital signal processing system (109) configured to set a drive signal frequency for the primary drive transducer (103), a voltage controlled oscillator (111) configured to receive an input indicative of the resonant frequency and to generate a first periodic signal at a first multiple of the resonant frequency, and a first phase locked loop (113), configured to receive the first periodic signal, and to generate a second periodic signal at a second multiple of the resonant frequency. The first and second periodic signals are used to control the operation of an analog-to-digital converter (ADC) (115) configured to sample the primary pick off signal and a digital-to-analog converter (DAC) (118) configured to generate a drive signal waveform applied to the primary drive transducer (103).