Analog Accumulator Auto-Zeroing Noise Reduction
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Solution Overview
Problem
Conventional noise-filtering techniques for analog accumulators do not effectively remove noise inserted by the accumulator itself, leading to undesirable noise levels in the output signal, which can mask the signal to be evaluated.
Innovation Solution
Implementing an auto-zeroing mechanism during sampling phases to disconnect the op-amp from the input signal and connect it to a reference voltage, allowing the accumulator to sample and compensate for noise, thereby reducing DC offset and flicker noise accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional noise-filtering techniques are used, then the circuit design remains simple, but the noise inserted by the accumulator into the output signal cannot be effectively removed
Solution Approach 1:
The accumulation period is divided into multiple sampling phases and transfer phases. During sampling phases, the sampling circuit is disconnected from the accumulation circuit to allow noise determination. During transfer phases, the sampled signal is transferred back to the accumulation circuit. This temporal segmentation allows the system to separately determine and compensate for noise without complicating the overall circuit design.
Solution Approach 2:
The system determines the noise inserted by the accumulator during sampling phases and uses this noise information to compensate for the noise in subsequent transfer phases. This feedback mechanism allows the system to correct the harmful noise effect using the same circuit components, maintaining design simplicity while improving signal quality.
2Device complexity
If the sampling circuit remains connected to the accumulation circuit during accumulation, then the circuit configuration remains simple, but noise inserted by the accumulator accumulates and masks the signal
Solution Approach 1:
The circuit operates in periodic cycles of sampling phases followed by transfer phases. During sampling phases, the sampling circuit is periodically disconnected from the accumulation circuit to determine noise levels. During transfer phases, the circuit reconnects to transfer the sampled signal. This periodic action maintains simple circuit configuration while periodically removing noise to preserve signal evaluation accuracy.
3Object-affected harmful factors
If auto-zeroing is implemented during sampling phases, then noise is effectively removed, but additional control complexity is introduced
Solution Approach 1:
The accumulation circuit performs auto-zeroing during sampling phases by disconnecting from the input signal and connecting to a reference voltage, allowing it to self-determine and self-compensate for noise. The same circuit components used for accumulation also perform the noise determination and compensation functions, eliminating the need for separate control circuits and maintaining simplicity.
Data Source
AI summary
Accumulators that operate to fully or partially remove noise from a signal, including removing noise inserted into the signal by the accumulator itself. In some embodiments, an accumulator may be operated in a sampling phase and a transfer phase each time the accumulator samples an input signal. In some such embodiments, an op-amp of an accumulation circuit of the accumulator may be auto-zeroed during some or all of the sampling phases of an accumulation period. In some embodiments in which the op-amp is auto-zeroed during some or all of the sampling phases, the accumulation circuit may include a holding capacitor that, during an auto-zeroing process, holds a value output by the op-amp during a prior transfer phase. Including such a holding capacitor in an accumulator may reduce a voltage that the op-amp output rises following the auto-zero process, which may reduce a bandwidth and noise of the accumulation circuit.