Interleaved ADC Sampling Clocks With Shared Timing Alignment
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Solution Overview
Problem
Time interleaved analog-to-digital converters (ADCs) face challenges in minimizing timing mismatches between channels, which lead to spectral artifacts and degrade the signal-to-noise ratio (SNR), making it difficult to achieve high-speed and low-power conversion efficiently.
Innovation Solution
The implementation of a circuitry that generates sampling clocks with shared common circuitry across multiple interleaved channels, utilizing pull-up/hold-down and boost circuitry to synchronize and control the timing relationship between sampling clocks, thereby minimizing timing skew and mismatch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If time interleaved ADC channels are used to increase sampling rate, then productivity is improved, but timing mismatch between channels increases causing spectral artifacts and degraded SNR
Solution Approach 1:
The patent merges the clock generation functions for multiple interleaved channels into a single unified circuit. A single clock signal is distributed to all channels, and a common pull-down circuit controls the timing of sampling clocks across all channels. This integration ensures uniform timing relationships between channels while maintaining high sampling rates, thereby improving productivity without sacrificing measurement precision.
Solution Approach 2:
The clock generation circuit is designed with universal functionality to serve multiple interleaved channels simultaneously. The same circuit structure and control logic are used for all channels, ensuring consistent timing behavior. This multi-functional approach allows the system to achieve high sampling rates across all channels while maintaining uniform timing relationships, resolving the contradiction between productivity and measurement precision.
2Device complexity
If separate clock generation circuitry is used for each interleaved channel, then device complexity is reduced, but timing skew between sampling clocks increases
Solution Approach 1:
The patent combines the clock generation circuitry into a single shared unit that serves all interleaved channels. Instead of having separate clock generation circuits for each channel, one unified circuit generates and distributes clock signals to all channels through a common pull-down circuit. This merging approach maintains stable timing relationships while avoiding the complexity of multiple independent clock generation circuits.
Solution Approach 2:
While the overall clock generation circuit is unified, the patent segments the control function by using a common pull-down circuit that can independently control the timing of sampling clocks for different channels. This segmentation allows precise timing control for each channel within the unified circuit framework, maintaining stability without requiring separate complex clock generation circuitry for each channel.
3Measurement precision
If foreground or background calibration is used to correct timing mismatches, then measurement precision is improved, but device complexity and overhead increase
Solution Approach 1:
The patent implements preliminary action by designing the clock generation circuit to inherently produce uniform timing relationships from the start. By using a single clock signal and a common pull-down circuit to control all channels simultaneously, the system establishes correct timing relationships before operation begins. This eliminates the need for subsequent calibration processes, improving measurement precision without adding device complexity or overhead.
Solution Approach 2:
The unified clock generation circuit with common pull-down control is self-service in nature, automatically maintaining uniform timing relationships across all channels during normal operation. The circuit inherently compensates for timing variations without requiring external calibration interventions. This self-correcting mechanism improves measurement precision while avoiding the complexity and overhead of separate calibration systems.
Data Source
AI summary
An example apparatus, system, and method for sampling in an interleaved sampling circuit having multiple channels. In an embodiment, an input clock is used to synchronize the transitions of sampling clocks from a first to second voltage level, relative to one another. The sampling clocks are input to a sampling circuit. The input clock switches a common switch that pulls each sampling clock to the second voltage level through a common path on input clock transitions from a first to a second clock state. The transition from the first to a second voltage level of each sampling clock triggers a sample taken on one of the channels. The first voltage level may be boosted to drive switches on in the sampling circuit. Synchronizing transitions of the outputs through the common switch and common path reduces timing mismatch between the sampling clocks controlling the channels.