Adaptive TI-ADC Sample Clock Alignment Using Phase Interpolation
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Solution Overview
Problem
Conventional methods for sample clock alignment in time-interleaved analog-to-digital converters (TI-ADCs) face challenges such as degraded clock signal quality, inability to control process/voltage/temperature/parasitic extraction (PVTE) variations, and increased power consumption, often introducing complexity and inefficiency.
Innovation Solution
The implementation of an M-phase input/M-phase output phase interpolator and adaptation logic for adaptive sample clock alignment, which generates and adjusts second-level clock signals in a track-and-hold circuit, allowing for precise detection and adjustment of alignment errors and flexible time-margin redefinition to mitigate PVTE variations and data-rate changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional methods for sample clock alignment are used in TI-ADCs, then clock signal quality is maintained with fixed alignment, but the system cannot adapt to PVTE variations and data-rate changes, leading to degraded performance
Solution Approach 1:
The patent implements dynamic clock alignment by making the clock signals adaptive rather than fixed. The system continuously adjusts clock phase and timing parameters in response to detected alignment errors, allowing the clock distribution system to adapt to PVTE variations and data-rate changes. This transforms the static clock alignment into a dynamic, self-correcting system that maintains synchronization across varying operating conditions.
Solution Approach 2:
The patent employs feedback mechanisms where alignment errors are detected and used to generate correction signals that adjust the clock phases. The system monitors the alignment status of clock signals across different ADC channels and feeds this information back to the clock generators, enabling continuous optimization of clock synchronization. This closed-loop feedback approach allows the system to automatically compensate for drift and variations without external intervention.
2Manufacturing precision
If multi-level sampling stages are implemented to capture wide-band signals, then signal conversion quality improves, but clock path delay variations increase due to logic depth differences
Solution Approach 1:
The patent segments the clock distribution system into multiple independently controllable phases, with each phase serving specific sampling stages. By dividing the clock signals into distinct phases (e.g., phi1, phi2, phi3, phi4) that can be independently adjusted, the system can compensate for delay variations in different clock paths. This segmentation allows precise control over the timing of each sampling stage, maintaining synchronization despite variations in logic depth across multiple sampling levels.
Solution Approach 2:
The patent changes clock signal parameters (phase, frequency, timing) dynamically to compensate for path delay variations. By adjusting the phase offsets and timing parameters of clock signals generated by PLLs and dividers, the system optimizes the alignment between clock edges and sampling instants across different ADC channels. This parameter adjustment enables the system to maintain precise clock alignment even when logic path lengths vary due to manufacturing tolerances or operating conditions.
3Measurement precision
If adaptive alignment mechanisms are added to detect and correct clock misalignment, then clock alignment precision improves, but power consumption increases
Solution Approach 1:
The patent implements self-service alignment where the system uses its own operational signals to detect and correct alignment errors. The adaptive alignment mechanism leverages the existing clock signals and ADC output data to generate alignment error information, eliminating the need for separate external alignment equipment. The system services its own synchronization needs by continuously monitoring its performance and making self-correcting adjustments, thereby reducing the power overhead associated with dedicated alignment hardware.
Solution Approach 2:
The patent makes the clock alignment system multi-functional by integrating alignment detection and correction capabilities into the existing ADC operational infrastructure. The same clock signals used for normal ADC operation are also used for alignment detection, and the correction mechanism serves both synchronization and performance optimization functions. This universal approach allows the system to achieve precise alignment without adding separate dedicated power-consuming alignment subsystems.
Data Source
AI summary
An apparatus may include a first clock generator configured to receive an input clock signal, and generate two or more first-level clock signals of a track-and-hold circuit, a phase interpolator configured to generate an interpolated clock signals, wherein the interpolated clock signal is based on the two or more first-level clock signals, and a second clock generator configured to generate two or more second-level clock signals based on the interpolated clock signal, wherein the phase of the two or more second-level clock signals relative to the phase of a respective first-level clock signal is determined, at least in part, by the phase of the interpolated clock signal.