Digital Chopping Feedback Circuit for Ripple Error Reduction
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Solution Overview
Problem
Current sensors face challenges with high frequency chopper noise causing residual offsets and in-band noise, which reduces the dynamic range and increases the ratio of smallest to largest signal, due to chopping of input signals for offset error reduction, leading to increased area consumption on integrated circuit chips.
Innovation Solution
A system comprising a first circuit, a second circuit, and a feedback circuit, where the second circuit chops input signals and provides digital output signals with error signals that are fed back through a digital to analog converter to reduce ripple error, using a chopping circuit, integrator circuit, and digital to analog converter circuit to accumulate and convert error signals into analog feedback, thereby reducing ripple error.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If chopping is applied to reduce offset errors, then offset accuracy is improved, but high frequency chopper noise is generated causing residual offsets and in-band noise
Solution Approach 1:
The patent implements a feedback circuit that detects chopper noise in the digital output signal and feeds back a compensating signal to cancel the noise. The feedback circuit includes a chopper noise detector that identifies high frequency chopper noise components and a signal combiner that adds the compensating signal to the original signal, thereby reducing residual offsets and in-band noise while maintaining measurement precision.
Solution Approach 2:
The patent introduces a digital filter as an intermediary component that processes the digital output signal to separate and remove chopper noise components before the signal is converted back to analog form. This digital filtering stage acts as a mediator between the chopping operation and the final output, eliminating harmful noise without affecting the useful signal.
2Object-generated harmful factors
If low-pass filtering is applied to filter chopper noise, then noise is reduced, but chip area is consumed
Solution Approach 1:
The patent replaces traditional analog low-pass filtering circuitry with a digital filtering approach implemented in the digital domain. This substitution uses digital signal processing techniques rather than physical RC filters or other analog components, significantly reducing the chip area required while maintaining effective chopper noise filtering performance.
3Measurement precision
If analog feedback loops are used to reduce offset error, then offset accuracy is improved, but chip area consumption increases due to large low-pass filter requirements
Solution Approach 1:
The patent replaces the traditional analog feedback loop with a digital feedback mechanism. Instead of using large analog low-pass filters in the feedback path, the system uses digital filtering and processing in the digital domain, then converts the processed signal back to analog form. This substitution dramatically reduces the chip area required for the feedback circuitry while maintaining offset error correction performance.
Solution Approach 2:
The patent moves the feedback processing from the analog domain to the digital domain, representing a dimensional change in the signal processing approach. By performing feedback operations on digital signals rather than analog signals, the system avoids the area-consuming analog filter components while achieving the same offset correction function.
4Object-generated harmful factors
If high chopping frequency is used to reduce noise, then noise filtering is improved, but dynamic range is reduced and the ratio of smallest to biggest signal increases
Solution Approach 1:
The patent extracts and removes the harmful chopper noise components from the signal using digital filtering techniques. By specifically targeting and eliminating the high frequency chopper noise components through digital filtering, the system maintains the benefits of high frequency chopping (effective noise separation) while removing the detrimental effects (residual noise and dynamic range reduction) through selective frequency component extraction and removal.
Data Source
AI summary
A system including a first circuit, a second circuit, and a feedback circuit. The first circuit is configured to provide input signals. The second circuit is configured to receive the input signals and provide digital output signals that correspond to the input signals. The feedback circuit includes a chopping circuit, an integrator circuit, and a digital to analog converter circuit. The chopping circuit is configured to receive the digital output signals and provide error signals that represent ripple error in the digital output signals. The integrator circuit is configured to accumulate the error signals and provide an accumulated error signal. The digital to analog converter circuit is configured to convert the accumulated error signal into an analog signal that is received by the second circuit to reduce the ripple error.