Reconfigurable Sigma-Delta Resonator for Overload Recovery
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Solution Overview
Problem
Higher order delta sigma modulators become unstable under overload conditions, leading to integrator saturation and oscillation, and existing recovery methods are often process and temperature dependent, disruptive, or require additional circuitry, limiting their adaptability and increasing component cost.
Innovation Solution
A reconfigurable local resonator with a T-shaped cell of capacitors and a switching stage is introduced, which can convert into a low pass filter in response to overload conditions, reducing feedback charge and improving stability without requiring additional area or increasing component cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If higher order delta sigma modulators are used to reduce quantization noise, then signal-to-noise ratio is improved, but stability deteriorates under overload conditions causing integrator saturation and oscillation
Solution Approach 1:
The patent applies dynamics by making the feedback path configurable between two states: a resonant feedback path for normal operation that reduces quantization noise, and a recovery path for overload conditions that prevents saturation. The switching mechanism dynamically transitions between these states based on overload detection, allowing the system to adapt its feedback characteristics to maintain stability while preserving signal-to-noise ratio performance.
Solution Approach 2:
The patent changes the feedback parameter (feedback path configuration) in response to overload conditions. By switching between different feedback paths with different characteristics (resonant vs. recovery), the system modifies its transfer function parameters to prevent integrator saturation during overload while maintaining optimal noise shaping during normal operation.
2Stability of the object's composition
If recovery circuits are added to handle overload conditions, then stability is improved, but device complexity increases due to additional circuitry occupying semiconductor die area
Solution Approach 1:
The patent achieves multi-functionality by configuring existing feedback path components (switches, capacitors, integrators) to serve dual purposes: the resonant feedback path components are used for both noise reduction during normal operation and for controlled recovery during overload conditions. This eliminates the need for separate dedicated recovery circuitry, reducing overall device complexity while maintaining stability.
Solution Approach 2:
The patent merges the recovery function with the existing feedback path structure. The recovery path shares components with the resonant feedback path, combining multiple functions into a unified structure that handles both noise shaping and overload recovery without requiring entirely separate circuit blocks, thereby minimizing die area occupation.
3Stability of the object's composition
If traditional recovery methods are used to return modulator to operation after overload, then stability is improved, but adaptability deteriorates as methods are process and temperature dependent and cannot be adapted to different signal voltages
Solution Approach 1:
The patent employs feedback mechanisms where the overload detection output controls the switching between feedback paths. This closed-loop approach automatically adjusts the feedback characteristics based on the actual operating conditions, making the recovery process adaptive to different signal voltages, process variations, and temperature conditions rather than relying on fixed threshold circuits.
Solution Approach 2:
The system dynamically adapts its feedback path configuration based on real-time overload detection, allowing the recovery behavior to adjust to different operating conditions including process and temperature variations. This dynamic adaptation replaces static, process-dependent recovery thresholds with a more robust conditional switching mechanism.
Data Source
AI summary
A delta sigma modulator includes two adders, an integrator stage, a reconfigurable local resonator, an analog-to-digital converter (ADC), and a digital-to-analog converter (DAC). A first adder receives an analog input signal at an additive input, and the integrator stage receives an output from the first adder and generates an integrated signal. The reconfigurable local resonator receives the integrated signal and generates a resonator output signal. A second adder receives the resonator output signal, the integrated signal, and the input signal. The ADC receives an output from the second adder and generates a digital output signal which can be provided to other circuits. The DAC receives the digital output signal, and generates and provides a feedback signal to a subtractive input of the first adder. The reconfigurable local resonator acts as a resonator, but reconfigures to act as a low pass filter in response to overload conditions.