Precision rate demodulation for a vibrating gyroscope
AssigneeSTMicroelectronics International N.V.
InventorsPavan Nallamothu, Milad Alwardi, Deyou Fang, Yamu Hu, David McClure
Life of this patent
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Abstract
According to an embodiment, a circuit is proposed for generating rate and quadrature demodulation signals, incorporating unidirectional hysteresis for negative edges. The circuit features a preliminary stage that amplifies the differential sinusoidal signal from gyroscopic proof mass oscillations; a gain stage for boosting this signal with adjustable hysteresis levels; an output stage delivering a full-swing square wave output; and a customizable offset component to deepen the drop in the non-inverting compared to the inverting signal for the third signal's falling edge.
Claims20
A circuit for demodulating rate and quadrature signals by applying a unidirectional hysteresis for a negative edge, the circuit comprising:
- a first stage configured to generate a first signal that is an amplification of a differential sine wave signal, the differential sine wave signal corresponding to an oscillation of a proof mass of a gyroscope;
- a gain stage configured to generate a second signal that is an amplification of the first signal from the first stage, a magnitude of the unidirectional hysteresis being controllable through the gain stage;
- an output stage configured to generate a third signal that is an amplification of the second signal from the gain stage, the third signal being a rail-to-rail square wave signal at an output of the circuit;
- and
- a programmable offset circuit configured to provide a programmable negative offset such that a non-inverting signal of the differential sine wave signal decreases further than the inverting signal of the differential sine wave signal for a falling edge of the third signal.
A system for demodulating rate and quadrature signals, the system comprising:
- a gyroscope configured to detect an oscillation of a proof mass due to a drive motion by generating first signals;
- a charge-to-voltage converter configured to convert the first signals to a differential sine wave signal, the first signals being charge signals, and the differential sine wave signal being equivalent voltage signals to the first signals;
- and
- a drive comparator configured to eliminate false pulses due to high-frequency signals and noise superimposed on top of the differential sine wave signal by applying a unidirectional hysteresis for a negative edge, the drive comparator comprising:
- a first stage configured to generate a second signal that is an amplification of the differential sine wave signal,
- a gain stage configured to generate a third signal that is an amplification of the second signal from the first stage, a magnitude of the unidirectional hysteresis being controllable through the gain stage,
- an output stage configured to generate an output signal that is an amplification of the third signal from the gain stage, the output signal being a rail-to-rail square wave signal at an output of the drive comparator, and
- a programmable offset circuit configured to provide a programmable negative offset such that a non-inverting signal of the differential sine wave signal decreases further than the inverting signal of the differential sine wave signal for a falling edge of the output signal.
A system for demodulating rate and quadrature signals, the system comprising:
- a drive comparator configured to eliminate false pulses due to high-frequency signals and noise superimposed on top of the differential sine wave signal by applying a unidirectional hysteresis for a negative edge, comprising:
- a first stage configured to generate a first signal that is an amplification of a differential sine wave signal, the differential sine wave signal corresponding to an oscillation of a proof mass of a gyroscope;
- a gain stage configured to generate a second signal that is an amplification of the first signal from the first stage, a magnitude of the unidirectional hysteresis being controllable through the gain stage;
- an output stage configured to generate a third signal that is an amplification of the second signal from the gain stage, the third signal being a rail-to-rail square wave signal at an output of the drive comparator;
- and
- a programmable offset circuit configured to provide a programmable negative offset such that a non-inverting signal of the differential sine wave signal decreases further than the inverting signal of the differential sine wave signal for a falling edge of the third signal;
- and
- a phase-locked loop (PLL) circuit and a phase frequency extractor (PFE) circuit coupled to the drive comparator and configured to generate demodulation signals based on the third signal.
Dependencies are inferred from the claim text.