| CPC B81B 7/008 (2013.01) [B81B 3/0043 (2013.01); B81B 2207/03 (2013.01); G02B 26/0833 (2013.01)] | 17 Claims |
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1. A method of operating a micro-electro mechanical systems (MEMS) device, comprising:
driving the MEMS device with a drive signal;
sensing movement of the MEMS device caused by the drive signal, and generating a sense signal indicative of the movement;
using a rotation-matrix approach to generate a reference cosine wave and a reference sine wave, the reference cosine wave and reference sine wave each having an amplitude of 1 and a same frequency as that of the sense signal;
multiplying the sense signal by the reference sine wave to produce a first product;
multiplying the sense signal by the reference cosine wave to produce a second product;
low-pass filtering the first product to produce a first intermediate output;
low-pass filtering the second product to produce a second intermediate output;
performing a 4-quadrant CORDIC technique on the first and second intermediate outputs to thereby determine a phase shift between the sense signal and the drive signal as well as an amplitude of the sense signal;
comparing the phase shift to a target phase shift to produce a phase error as a difference therebetween;
comparing the amplitude of the sense signal to a target amplitude to thereby produce an amplitude error as a difference therebetween; and
modifying the drive signal based upon the phase error and the amplitude error so that the phase error and amplitude error are eliminated by:
generating a control signal based upon the phase error;
generating the frequency drive signal based upon the control signal, and modifying phase of the drive signal based upon the frequency drive signal such that the phase error is eliminated; and
generating a voltage drive signal to the driver based upon the amplitude error, and modifying amplitude of the drive signal based upon the voltage drive signal such that the amplitude error is eliminated.
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