Effect of digital-to-analog converter glitch on the modulation and demodulation of a digital closed-loop fiber-optic gyroscope

Dead zone or bias error, which is induced by a glitch in the digital-to-analog converter (DAC) in a fiber-optic gyroscope (FOG) is proposed. The DAC glitch produces different forms of jamming signals and ultimately results in demodulation errors which depend on the modulation frequency and pass through zero at the proper frequency. The demodulation error is modelled as a piecewise function according to its characteristic, i.e., it appears to be a constant value when the staircase ramp ranges from 2ⁿ⁻² to 2ⁿ⁻¹ and remains zero when the staircase ramp outs of this range, where n is the bit length of the register. Simulations reveal that the staircase ramp oscillates, which leads to the dead zone when the equivalent angular velocity induced by the demodulation error is greater than the input angular velocity; otherwise, the staircase ramp resets with different slopes, which results in a bias error. We test the DAC glitch effect in a closed-loop FOG. The test results reveal that the dead zone induced by the demodulation error is consistent with that of the simulation results.