Time-Interleaved ADC Clock Synchronization With Autonomous Phase Tracking
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Solution Overview
Problem
Synchronization of sampling clock signals between distributed groups of unit ADCs in massively time-interleaved ADCs is challenging, and synchronization errors are difficult to detect and correct, especially under Process-Voltage-Temperature-Extraction (PVTE) variations and ambient aggressor signals, leading to degraded system performance.
Innovation Solution
An autonomous synchronization architecture using a multi-group multiple input multiple output phase interpolator (MG-MIMO-PI) with adaptive tracking across PVTE variations, eliminating the need for global reset signals and correcting synchronization errors on-the-fly, by utilizing a MG-MIMO-PI, clock divider/token generators, and replica and phase detector circuits to align clock signals and tokens.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a large number of unit ADCs are connected by multi-level track-and-hold circuits to support higher speed communications, then the ADC operating speed is improved, but synchronization of sampling clock signals between distributed groups becomes more difficult and errors are harder to detect
Solution Approach 1:
The patent implements a feedback mechanism where each ADC group monitors its own clock signal phase relative to a reference and automatically adjusts its sampling timing. Phase detector circuits detect synchronization errors and generate correction signals that are fed back to the clock distribution network, enabling continuous self-correction without external intervention. This resolves the contradiction by maintaining high-speed operation while ensuring reliable synchronization through automatic feedback control.
Solution Approach 2:
The synchronization system is designed to be self-correcting, where the ADC groups autonomously detect and correct their own synchronization errors without requiring global reset signals or external calibration. Each group uses local phase detection and adjustment mechanisms to maintain proper timing alignment, enabling the system to service itself and maintain reliability at high operating speeds.
2Adaptability or versatility
If unit ADCs are distributed across multiple groups to reduce power and size constraints, then device scalability is improved, but detection of synchronization errors becomes more difficult
Solution Approach 1:
The patent divides the large-scale ADC system into multiple independent ADC groups, each with its own synchronization monitoring and correction capabilities. This segmentation allows each distributed group to autonomously detect and report synchronization status, making error detection feasible across the entire system despite the large number of distributed units. Each segment contributes to overall system reliability through independent monitoring.
Solution Approach 2:
The synchronization architecture implements universal monitoring mechanisms that function across all ADC groups regardless of their specific location or configuration. The phase detector circuits and error detection logic are designed to work uniformly across the entire distributed system, enabling consistent synchronization verification across all scalable units without requiring group-specific detection methods.
3Reliability
If global reset signals are used to synchronize distributed ADC groups, then initial synchronization is achieved, but the system cannot correct synchronization errors that occur during operation under PVTE variations
Solution Approach 1:
The patent transitions from static initial synchronization using global reset signals to dynamic continuous synchronization. The system employs real-time phase detection circuits that continuously monitor clock signal alignment and automatically adjust timing parameters during operation. This dynamic approach allows the system to adapt to PVTE variations and correct synchronization errors as they occur, rather than relying solely on initial static alignment.
Solution Approach 2:
The system performs preliminary synchronization using global reset signals to establish initial clock alignment, then prepares and activates continuous real-time correction mechanisms that take over during operation. The phase detectors and adjustment circuits are pre-configured to immediately begin correcting any drift or errors that develop after initial synchronization, ensuring both reliable startup and ongoing adaptability.
Data Source
AI summary
An apparatus includes a first phase interpolator configured to receive a first clock signal and generate a second clock signal, and an ADC that includes a clock divider configured to generate a third clock signals based on the second clock signal, a token generator configured to generate a first token signal, a first phase detector configured to generate a first and second output based on the first and third clock signals, and a second phase detector configured to generate a third output based on the token signal. Control logic may be provided to perform a foreground calibration to align the first token signal with a second token signal of a second ADC-group, and a background calibration to align the third clock signal with the first clock signal.