Passive Noise-Shaping SAR ADC With Tunable Residue Amplification
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Solution Overview
Problem
Conventional passive noise-shaping SAR ADCs face limitations due to residue amplitude degradation and the need for additional comparator inputs, which hinder their performance in low-power applications.
Innovation Solution
A passive noise-shaping SAR ADC design utilizing tunable capacitance in passive elements for residue amplification, eliminating the need for multiple-input-pair comparators and achieving noise-shaping without operational amplifiers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If a conventional passive noise-shaping SAR ADC uses a passive integrator without residue amplification, then power consumption is reduced, but residue amplitude degrades each time charge sharing occurs
Solution Approach 1:
The patent employs dynamic capacitance values in the passive integrator, where the capacitance is adjusted based on the conversion stage. By making the capacitance dynamic rather than fixed, the system compensates for residue amplitude degradation without requiring active amplification, thus maintaining low power consumption while improving residue reliability
Solution Approach 2:
The patent changes the capacitance parameter of the passive integrator to achieve residue amplification. By carefully selecting and adjusting capacitance values in the passive integrator circuit, the system amplifies the residue signal passively, avoiding the need for power-hungry active operational amplifiers while maintaining signal integrity
2Measurement precision
If a conventional passive noise-shaping SAR ADC requires a comparator with an additional input differential pair for the residue, then noise-shaping is achieved, but comparator noise increases
Solution Approach 1:
The patent extracts the residue signal processing function from the comparator by implementing a separate passive integrator stage. The residue is integrated and amplified passively before being fed back to the comparator, allowing the comparator to operate with its standard single-input differential pair and avoid the additional noise introduced by multiple input pairs
3Reliability
If a conventional active noise-shaping SAR ADC uses an active integrator with operational amplifier, then residue amplification is achieved, but power consumption increases
Solution Approach 1:
The patent replaces the active operational amplifier-based integrator with a passive RC or RLC integrator circuit. This substitution eliminates the need for power-hungry active components while achieving the same integration and amplification function through passive elements, dramatically reducing power consumption while maintaining residue amplification capability
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances noise transfer function and reduces signal gain and residue gain degradation, making it suitable for low-power applications.
Implementation Method 1
The passive noise-shaping circuit includes at least one passive element with tunable capacitance that is configured to perform residue amplification
Data Source
AI summary
A passive noise-shaping successive-approximation analog-to-digital converter (SAR ADC) includes a SAR ADC circuit and a passive noise-shaping circuit. The SAR ADC circuit performs conversion upon an analog input signal and extracts residue at an end of the conversion. The passive noise-shaping circuit processes the residue and feeds a processed residue back to the SAR ADC circuit. The passive noise-shaping circuit includes at least one passive element with tunable capacitance that is used to perform residue amplification.