Low-Power Signaling Interface With Digital Phase Alignment
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Solution Overview
Problem
High-speed signaling between integrated circuit devices from disparate temperature domains faces challenges due to difficulties in implementing precise timing alignment with low power expenditure, especially in cryogenic environments where analog phase-adjust techniques are impracticable.
Innovation Solution
The use of digital timing-phase alignment circuitry, particularly in superconducting domains with RSFQ logic elements, enables purely digital timing-phase adjustment by extracting timing events from an overclocked timing reference, allowing for precise phase alignment with low power consumption and high signaling rates across temperature domains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If analog phase-adjust techniques are used for timing alignment, then timing precision can be achieved, but power consumption increases and the technique becomes impracticable in cryogenic environments
Solution Approach 1:
The patent replaces analog phase-adjust techniques with purely digital timing-phase adjustment circuitry. The digital circuitry extracts timing events from an overclocked timing reference signal and uses digital logic (phase counters, count comparators, and multiplexers) to achieve precise timing alignment without the power consumption and implementation difficulties of analog techniques in cryogenic environments
Solution Approach 2:
The patent changes the operating parameters by using an overclocked timing reference signal (FCLK) that runs at a higher frequency than the data rate reference clock (RefCK). This allows the digital circuit to achieve fine-grained timing control by selecting different phases from the overclocked signal, enabling precise timing alignment with low power consumption
2Measurement precision
If timing alignment is implemented in cryogenic environments, then precise timing can be achieved, but device complexity and implementation difficulty increase
Solution Approach 1:
The patent substitutes complex analog phase-adjust circuitry with simpler digital logic elements that are well-suited for cryogenic operation. The digital implementation uses standard logic components (counters, comparators, multiplexers) that can be fabricated using superconducting logic families like RSFQ, reducing implementation complexity in cryogenic environments
Solution Approach 2:
The patent extracts timing events from the overclocked timing reference signal using digital circuitry. The phase counter captures timing events at the higher FCLK rate, and the count comparator extracts the appropriate phase information, separating the timing extraction function from the data processing function to simplify the overall system
3Productivity
If higher signaling rates are used, then data transmission speed increases, but timing alignment precision becomes more difficult to maintain
Solution Approach 1:
The patent performs preliminary timing calibration by extracting phase information from the overclocked timing reference before data transmission. The receive clock generator pre-adjusts the timing of received data by selecting the appropriate phase from the FCLK signal based on calibration measurements, ensuring timing alignment is established before high-speed data transmission begins
Solution Approach 2:
The patent implements dynamic timing adjustment where the receive clock generator can continuously adjust the phase of the receive clock signal based on timing calibration feedback. The digital circuitry allows for real-time phase adjustments by changing the count-match value in the count comparator, enabling the system to maintain timing precision even as signaling rates increase
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach achieves high-precision timing alignment with extremely low power expenditure, enabling fast and reliable signaling between integrated circuit devices across disparate temperature domains, even when one device is in a cryogenic environment and the other is warmer, with signaling rates up to ten times the data rate.
Implementation Method 1
The use of digital timing-phase alignment circuitry, particularly in superconducting domains with RSFQ logic elements
Data Source
AI summary
In a chip-to-chip signaling system includes at least one signaling link coupled between first and second ICs, the first IC has an interface coupled to the signaling link and timed by a first interface timing signal. The second IC has an interface coupled to the signaling link and timed by a second interface timing signal that is mesochronous with respect to the first interface timing signal. The second IC further has phase adjustment circuitry that adjusts a phase of the second interface timing signal using a digital counter implemented with Josephson-junction circuit elements.