Bandpass Sigma-Delta Gyroscope ADC With Integrated C2V Delay Control
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Solution Overview
Problem
Conventional gyroscope technologies experience ADC offset non-linearity due to changes in delays of capacitance-to-voltage (C2V) converters over temperature, leading to phase shifts and performance degradation.
Innovation Solution
Integrating C2V converters within bandpass sigma-delta ADCs of the gyroscope, using feedback loops to reduce propagation delays and increase loop gains, thereby minimizing non-linearity effects and reducing the difference between sense and drive mass output delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate C2V converters are used for drive and sense outputs, then the gyroscope can process both signals independently, but temperature-induced delay changes cause phase shifts and ADC offset non-linearity
Solution Approach 1:
The patent merges the C2V converter with the sigma-delta ADC into a single integrated unit. The C2V converter is positioned at the input stage of the sigma-delta ADC, allowing the capacitance conversion and digital conversion processes to occur within a unified structure. This integration ensures that both drive and sense signals undergo identical conversion processes, eliminating differential delay variations that cause phase shifts and ADC offset non-linearity while maintaining independent signal processing capability.
2Reliability
If C2V converters are integrated within sigma-delta ADCs, then propagation delays are compressed and loop gains are increased, but the circuit complexity of the ADC increases
Solution Approach 1:
The integrated C2V converter within the sigma-delta ADC uses the ADC's own feedback loop and high loop gain to automatically compensate for its own propagation delays. The feedback mechanism inherently corrects delay variations without requiring external compensation circuits or additional components. This self-service approach improves delay stability and reliability while avoiding the need for separate compensation hardware that would further increase circuit complexity.
3Reliability
If feedback loops are used to reduce propagation delays, then delay stability improves, but the device complexity increases
Solution Approach 1:
The feedback loop in the sigma-delta ADC serves multiple functions simultaneously: it performs the primary function of digital-to-analog conversion and feedback for noise shaping, while also providing automatic compensation for C2V converter propagation delays. This multi-functionality allows the same feedback infrastructure to address both conversion accuracy and delay stability, improving reliability without requiring separate feedback circuits dedicated solely to delay compensation.
Data Source
AI summary
Facilitating minimization of non-linearity effects of a delay of a capacitance-to-voltage (C2V) converter on an output of a gyroscope is presented herein. A sense output signal of a sense mass of the gyroscope and a drive output signal of a drive mass of the gyroscope are electronically coupled to respective analog-to-digital converter (ADC) inputs of bandpass sigma-delta ADCs of the gyroscope. The bandpass sigma-delta ADCs include respective C2V converters that are electronically coupled, via respective feedback loops, to the respective ADC inputs to facilitate reductions of respective propagation delays of the bandpass sigma-delta ADCs. Respective ADC outputs of the bandpass sigma-delta ADCs are electronically coupled to demodulator inputs of a demodulator of the gyroscope that transforms the sense output into an output of the MEMS gyroscope representing an external stimulus that has been applied to the sense mass.