Anti-aliasing Sample-and-Hold Circuit with Decimated FIR Filter
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Solution Overview
Problem
Existing sample-and-hold circuits face challenges with aliasing noise, particularly due to the difficulty in efficiently filtering high-frequency noise without consuming excessive power or increasing die area, which complicates integration with analog-to-digital converters (ADCs) and can degrade signal linearity and introduce phase distortion.
Innovation Solution
An anti-aliasing sample-and-hold circuit that samples the input signal at twice the frequency of the sample signal, using a sample stage with multiple switches and capacitors to aggregate voltage samples during both sample and hold phases, and a hold stage with an amplifier to output decimated samples, effectively acting as a decimated finite impulse response (FIR) filter to attenuate noise at the sampling frequency and its multiples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If multi-stage active analog filters are used to filter high-frequency noise, then noise attenuation is improved, but die area increases and power consumption increases
Solution Approach 1:
The patent extracts the anti-aliasing function from traditional multi-stage active analog filters and implements it within the sample-and-hold circuit using a decimated FIR filter structure. This removes the need for separate filter components, reducing die area while maintaining noise attenuation performance.
Solution Approach 2:
The sample-and-hold circuit is designed to perform multiple functions: signal sampling, signal holding, and anti-aliasing filtering. The decimated FIR filter is integrated into the hold stage, allowing the same circuit to simultaneously sample, hold, and filter the signal, eliminating the need for separate filter components.
2Object-affected harmful factors
If multi-stage active analog filters are used to filter high-frequency noise, then noise attenuation is improved, but power consumption increases
Solution Approach 1:
The patent extracts the anti-aliasing function from power-consuming multi-stage active analog filters and implements it within the sample-and-hold circuit using a decimated FIR filter structure. This removes the need for separate filter components, reducing power consumption while maintaining noise attenuation performance.
Solution Approach 2:
The sample-and-hold circuit is designed to perform multiple functions: signal sampling, signal holding, and anti-aliasing filtering. The decimated FIR filter is integrated into the hold stage, allowing the same circuit to simultaneously sample, hold, and filter the signal, eliminating the need for separate filter components and their associated power consumption.
3Device complexity
If traditional sample-and-hold circuits are used, then circuit simplicity is maintained, but aliasing noise is not effectively attenuated
Solution Approach 1:
The sample-and-hold circuit is designed to perform multiple functions: signal sampling, signal holding, and anti-aliasing filtering. The decimated FIR filter is integrated into the hold stage, allowing the same circuit to simultaneously sample, hold, and filter the signal, eliminating the need for separate filter components.
Solution Approach 2:
The patent employs a decimated FIR filter with periodic sampling and holding phases. The filter uses periodic clock signals to sample the input signal during the sample phase and hold the sampled value during the hold phase, creating a periodic action that inherently provides anti-aliasing functionality.
4Object-affected harmful factors
If higher sampling frequency is used to reduce aliasing, then noise attenuation is improved, but power consumption increases and die area increases
Solution Approach 1:
The patent employs a decimated FIR filter with periodic sampling and holding phases. The filter uses periodic clock signals to sample the input signal during the sample phase and hold the sampled value during the hold phase, creating a periodic action that inherently provides anti-aliasing functionality without requiring excessively high sampling frequencies.
Data Source
AI summary
Systems and methods are included for providing anti-aliasing in a sample-and-hold circuit. One embodiment of the present invention includes a method for sampling of an input signal for providing to an analog-to-digital converter. The method comprises generating a sample signal having a given frequency and a period that defines both a sample phase and a hold phase. The method also comprises sampling the input signal at both the sample phase and the hold phase. The method further comprises generating a decimated output sample that is an aggregate of consecutive samples of the input signal obtained during the sample phase and the hold phase.