Noise-Shaping SAR ADC Using Passive RC Feedback
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current analog-to-digital converters (ADCs) face challenges in effectively shaping noise, particularly in achieving high noise transfer function performance without increasing power consumption or area overhead, especially in noise-shaping SAR ADCs.
Innovation Solution
The proposed ADC incorporates a capacitor array, an auxiliary capacitor, and switch configurations to implement a noise transfer function that shapes noise away from desired frequency bands, using a variable capacitance mechanism to optimize noise transfer and reduce the need for additional active components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If noise shaping is implemented using traditional active components (opamps, integrators), then noise transfer function performance is improved, but power consumption and area overhead increase
Solution Approach 1:
The patent replaces active electronic components (opamps, integrators) with passive RC circuits to implement the noise transfer function. This substitution eliminates the need for power-consuming active devices while achieving the same noise shaping effect through passive resistor-capacitor networks configured in feedback loops around the SAR ADC.
Solution Approach 2:
The patent extracts and removes the active components (opamps and integrators) from the noise shaping circuitry, retaining only the essential passive RC elements. This extraction reduces power consumption while preserving the core noise transfer function through the passive feedback network.
2Measurement precision
If noise shaping is implemented using traditional active components (opamps, integrators), then noise transfer function performance is improved, but area overhead increases
Solution Approach 1:
The patent replaces active electronic components (opamps, integrators) with passive RC circuits to implement the noise transfer function. This substitution eliminates the need for power-consuming active devices while achieving the same noise shaping effect through passive resistor-capacitor networks configured in feedback loops around the SAR ADC.
Solution Approach 2:
The patent extracts and removes the active components (opamps and integrators) from the noise shaping circuitry, retaining only the essential passive RC elements. This extraction reduces power consumption while preserving the core noise transfer function through the passive feedback network.
3Measurement precision
If a variable auxiliary capacitor is used to optimize noise transfer, then noise shaping capability is improved, but device complexity increases
Solution Approach 1:
The patent employs a variable auxiliary capacitor that can switch between different capacitance values to optimize the noise transfer function for different operating conditions. This dynamic adjustment allows the passive RC network to adaptively shape noise across varying frequency ranges while maintaining simplicity through binary-weighted capacitor switching.
Solution Approach 2:
The patent changes the capacitance parameter of the auxiliary capacitor to optimize noise transfer performance. By adjusting the capacitance value, the pole locations of the noise transfer function can be controlled to achieve optimal noise shaping for different signal frequencies and sampling rates.
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
This solution enhances noise shaping capabilities while minimizing power consumption and area overhead, achieving improved noise transfer function performance and efficiency in ADCs.
Implementation Method 1
a capacitor array (e.g., Cs in FIG. 3a, 4a, 6a or 7a), an auxiliary capacitor (e.g., Cr in FIG. 3a, 4a, 6a or 7a)
Data Source
Figure 1
Figure 2
Figure 3a
AI summary
The invention provides an analog-to-digital converter (ADC) converting an input signal to an output signal. The ADC may comprise a main circuit and a comparator coupled to the main circuit. The main circuit may: transfer the input signal by an input transfer block, filter an error signal by a loop filter, and combine the transferred input signal and the filtered error signal to form a combined signal. The comparator may quantize the combined signal to provide the output signal, wherein the error signal may reflect a difference between the combined signal and the output signal.