Phase Interpolator Error Correction for Precise Timing Control
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Solution Overview
Problem
Phase interpolators in digital and mixed digital-analog circuits face limitations due to integral non-linearity, which restrict the accuracy of timing control and are challenging to compensate for variations in process, voltage, temperature, and frequency conditions.
Innovation Solution
Implementing a controller with error correction data that utilizes the mathematical derivative of phase interpolator error correction data, allowing for a smaller table to store error correction data and dynamically adjust corrections based on varying conditions, reducing the need for a full error correction table and minimizing die area usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a full error correction table is used to compensate for phase interpolator non-linearity, then timing control precision is improved, but die area is increased
Solution Approach 1:
The error correction table is segmented into multiple smaller sub-tables, each storing correction data for a specific phase range or interpolation segment. This allows the system to achieve comprehensive error correction coverage while using less total memory space than a single full-size table would require.
Solution Approach 2:
Error correction data is pre-calculated and stored in compact sub-tables during the design phase. The system performs preliminary segmentation and optimization of the correction data, so that during operation, only minimal memory access is needed to apply corrections, reducing the required die area for storage.
2Device complexity
If traditional PLL is used for clock signal generation, then device complexity is reduced, but timing precision deteriorates
Solution Approach 1:
A phase interpolator is introduced as an intermediary component between the traditional PLL and the clock distribution network. The phase interpolator takes the PLL output and generates multiple phase-shifted clock signals with high precision by interpolating between reference phases, thereby achieving superior timing precision while maintaining the simplicity of the underlying PLL architecture.
Solution Approach 2:
The phase interpolator circuit is designed to serve multiple functions: it generates phase-shifted clock signals for different functional blocks, provides error correction through segmented tables, and maintains synchronization across the system. This multi-functionality allows a single added component to deliver precise timing control without proportionally increasing overall system complexity.
Data Source
AI summary
Apparatuses and methods for phase interpolators are provided. An example apparatus comprises a phase interpolator and a controller coupled to the phase interpolator. The controller is configured to provide a digital timing code to the phase interpolator, and the phase interpolator is configured to apply a correction to the received digital timing code based, at least in part, on phase interpolator error correction data from a data structure containing phase interpolator error correction data.