Time-Interleaved SAR-ADC Clock Delay Calibration for Skew Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Time-interleaved sequential approximation register (SAR) analog-to-digital converters (ADCs) face synchronization issues due to varying propagation delays of clock signals across different SAR-ADCs on an integrated circuit, leading to skew and inaccurate data conversion, especially under IC and environmental fluctuations.
Innovation Solution
A dynamic clock calibration system using variable delay clock circuits and phase-difference detection to adjust clock delays, ensuring synchronization of clock signals with sampling points, and generating a delay control signal to maintain consistent clock delays across SAR-ADCs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple SAR-ADCs are time-interleaved to increase conversion speed, then productivity is improved, but clock signal propagation delays cause synchronization skew between ADCs
Solution Approach 1:
The patent applies preliminary action by introducing variable delay circuits that pre-adjust clock signals before they reach each SAR-ADC. These circuits compensate for propagation delays by adding appropriate delay amounts to clock signals based on their destination ADC's position, ensuring all ADCs receive synchronized clock signals at their respective sampling points before conversion begins
Solution Approach 2:
The patent implements parameter changes by dynamically adjusting the delay parameters of clock signals using variable delay circuits. The delay amount for each clock signal is programmably controlled to match the specific propagation characteristics of its path, allowing the system to adapt to different physical layouts and environmental conditions while maintaining synchronization
2Reliability
If variable delay circuits are used to synchronize clock signals, then clock synchronization is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by implementing delay adjustment functionality specifically at the locations where clock signals are distributed to each SAR-ADC. Rather than globally redesigning the entire clock distribution system, variable delay circuits are locally inserted at critical points to provide precise synchronization control where needed, minimizing overall system complexity
Solution Approach 2:
The patent uses variable delay circuits as intermediary components between the clock source and individual SAR-ADCs. These intermediary circuits act as buffer zones that can independently adjust timing without affecting the core ADC conversion functionality or the main clock distribution architecture, thereby isolating complexity to manageable segments
3Reliability
If delay adjust signals are dynamically controlled to maintain synchronization under environmental fluctuations, then reliability is improved, but ease of operation decreases
Solution Approach 1:
The patent implements feedback mechanisms where the system continuously monitors clock signal propagation delays and automatically adjusts delay adjust signals to maintain synchronization. This closed-loop approach eliminates the need for manual calibration under varying environmental conditions, as the system self-corrects by detecting timing deviations and applying compensatory delay adjustments in real-time
Solution Approach 2:
The patent enables self-service by designing the calibration system to automatically perform synchronization adjustments without external intervention. The variable delay circuits are configured to autonomously adapt to environmental changes such as temperature variations and voltage fluctuations, managing their own calibration needs through integrated control logic that responds to actual timing conditions
Data Source
AI summary
A time-interleaved SAR-ADC employs calibrated SAR-ADC circuits to convert sampled voltage levels into serial digital data. Variable delay clock circuits synchronize clock signals received at the respective SAR-ADCs to sampling points of analog serial data. IC and environmental fluctuations cause delay in the variable delay clock circuits to skew the clock signals. A calibrated SAR-ADC detects changes to the delays in the variable delay clock circuits. By delaying a first clock signal in the variable delay clock circuit, and comparing a phase of the delayed clock signal to a phase-shifted clock signal having a known phase shift relative to the first clock signal, a change in the delay of the variable delay clock circuit can be detected as a phase difference. Based on an indication of a phase difference, a delay control signal is generated to control the delay in the variable delay clock.