Clock Domain Timing Loop for ADC Data Synchronization
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Solution Overview
Problem
The synchronization of digital data between delay and digital domains in wireless communication devices is challenged by the data-dependent variation of the delay domain clock signal, leading to timing errors and potential data loss due to varying phase or duty cycle of the delay domain clock signal.
Innovation Solution
A circuit is introduced with a clock delay driver generating early and late clock signals relative to the digital domain clock, coupled with a timing error detection circuit to adjust the programmable delay, ensuring synchronization by detecting and correcting timing errors through a timing loop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If delay domain ADC is used for high performance applications, then conversion performance is improved, but timing synchronization between clock domains deteriorates due to data-dependent clock variation
Solution Approach 1:
The patent applies preliminary action by generating early and late clock signals in advance before the actual data transfer occurs. These clock signals are prepared with predetermined timing offsets to proactively compensate for potential timing variations, ensuring that synchronization requirements are met even when delay domain clock phase varies with input data.
Solution Approach 2:
The patent implements feedback through a timing error detection circuit that monitors the actual timing relationship between delay domain and digital domain clocks. The detection circuit generates error flags that feed back to control the selection of early or late clock signals, creating a closed-loop system that continuously corrects synchronization errors caused by data-dependent clock variation.
2Reliability
If early and late clock signals are generated with timing loop control, then timing error detection and correction is improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the clock signal generation into distinct components: early clock signal generation, late clock signal generation, and nominal clock signal generation. Each component is independently controlled and can be selectively used based on timing requirements. This modular segmentation allows the complex timing control function to be implemented through simpler, dedicated circuit blocks rather than a monolithic complex system.
3Reliability
If clock delay is adjusted to compensate for timing errors, then data synchronization is improved, but loss of time occurs due to calibration and adjustment operations
Solution Approach 1:
The patent implements continuity of useful action by maintaining the timing loop operation in a continuous ready state rather than performing discrete calibration cycles. The early and late clock signals are continuously generated and monitored, allowing the system to immediately respond to timing errors without interruption to the data conversion process. This eliminates idle calibration time and ensures uninterrupted useful operation.
Data Source
AI summary
Analog-to-digital converter (ADC) circuitry including a delay domain ADC that outputs converted analog input data along with a delay domain clock. A clock delay driver outputs a digital domain clock, an early clock leading the digital domain clock signal, and a late clock lagging the digital domain clock. An output latch latches the ADC output by the digital domain clock signal. The circuitry includes a timing error detection circuit with inputs receiving the delay domain clock, the early clock, and the late clock. The timing error detection circuit outputs early and late fail flags responsive to detecting timing errors of the digital domain clock relative to the early and late clocks, respectively. Timing loop circuitry has an input coupled to the error flag output of the timing error detection circuitry, and an output coupled to a control input of the clock delay driver.