MASH Sigma-Delta ADC Calibration for Quantization Error Cancellation
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Solution Overview
Problem
MASH type sigma-delta analog/digital converters face challenges in enhancing resolution due to characteristic variations in analog circuits, with existing calibration methods being insufficient in effectively canceling quantization errors, leading to reduced performance in millimeter wave radar systems.
Innovation Solution
The implementation of a MASH type sigma-delta analog/digital converter with a probe signal generation circuit, adaptive filters, and a noise cancel circuit that searches for and adjusts transfer functions of both modulators and noise cancel filters to accurately cancel quantization errors, allowing for high-resolution performance even with characteristic variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing calibration methods are used in MASH type sigma-delta ADC, then the device can operate, but quantization errors cannot be sufficiently canceled and resolution cannot be enhanced
Solution Approach 1:
The patent implements a feedback mechanism where the output of the first quantizer is fed back through an adaptive filter to the input of the first modulator. The adaptive filter continuously adjusts its coefficients based on the observed quantization errors, creating a closed-loop system that actively compensates for characteristic variations in the analog circuit, thereby enabling sufficient quantization error cancellation and resolution enhancement
Solution Approach 2:
The patent dynamically changes the parameters of the adaptive filter (specifically the filter coefficients) based on the observed quantization errors. By adapting the filter parameters in real-time to match the actual characteristic variations of the analog circuit, the system achieves accurate quantization error cancellation that static calibration methods cannot provide
2Measurement precision
If characteristic variations occur in analog circuit, then the ADC can still operate, but resolution enhancement becomes impossible
Solution Approach 1:
The patent transforms the static calibration approach into a dynamic system by implementing an adaptive filter that continuously adjusts its coefficients in response to characteristic variations in the analog circuit. This dynamic adaptation allows the system to maintain high resolution performance despite changes in analog circuit characteristics over time, temperature, or manufacturing variations
Solution Approach 2:
The adaptive filter automatically detects and compensates for characteristic variations in the analog circuit without requiring external intervention or manual recalibration. The system monitors its own quantization errors and self-adjusts the filter coefficients to maintain optimal performance, enabling resolution enhancement even when analog circuit characteristics drift
3Ease of manufacture
If calibration is performed using U.S. Pat. No. 6,970,120 or Non-Patent Literature 1 methods, then some calibration is achieved, but quantization errors cannot be sufficiently canceled
Solution Approach 1:
The patent enhances existing calibration methods by implementing a continuous feedback loop where quantization errors are monitored and used to dynamically adjust adaptive filter coefficients. Unlike static calibration methods, this feedback mechanism ensures that quantization errors are actively canceled throughout operation, maintaining high reliability even as circuit characteristics vary
Solution Approach 2:
The adaptive calibration system automatically adjusts itself based on observed quantization errors without requiring external recalibration procedures. The system monitors its own performance and self-corrects for characteristic variations, providing sufficient quantization error cancellation that manual or static calibration methods cannot achieve
Data Source
AI summary
A modulator includes an analog integrator including an analog circuit and a quantizer quantizing its output signal. An external input signal is input thereto. A modulator is coupled to the latter stage of the modulator, and includes a quantizer. A probe signal generation circuit injects a probe signal to the modulator. An adaptive filter searches for a transfer function of the modulator by observing an output signal of the quantizer in accordance with a probe signal. Another adaptive filter searches for a transfer function of the modulator by observing an output signal of the quantizer in accordance with the probe signal. A noise cancel circuit cancels a quantization error generated by the quantizer using search results of the adaptive filters.