Superconducting Interface Circuits for Cryogenic CMOS Signal Conversion
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Solution Overview
Problem
Interfacing with superconducting circuits poses challenges due to operational temperature differences, incompatible data representations, and high data rates, requiring complex signal conversions and specialized equipment.
Innovation Solution
The implementation of Reciprocal Quantum Logic (RQL) signaling and interface driver/receiver circuits that convert between high-frequency superconducting signals and lower-frequency external systems, using single flux quanta and Josephson junctions to encode and process data, enabling compatibility with standard interfaces like IEEE1149.1 JTAG.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If superconducting circuits operate at very low temperatures (milliKelvins), then power efficiency and speed are improved, but interfacing with room temperature test equipment becomes challenging
Solution Approach 1:
The patent introduces an intermediary interface circuit that operates at intermediate temperatures between the superconducting circuit (milliKelvins) and room temperature test equipment. This interface circuit includes temperature-stabilized components and signal conditioners that bridge the thermal and electrical gaps, enabling communication without requiring test equipment to operate at cryogenic temperatures.
Solution Approach 2:
The system is divided into distinct thermal zones: a cryogenic section containing the superconducting logic circuit, an intermediate section with temperature-stabilized interface circuitry, and a room temperature section with standard test equipment. This segmentation allows each component to operate in its optimal temperature range while maintaining system-wide functionality.
2Use of energy by moving object
If data in superconducting circuits is represented as pulses rather than binary voltage values, then power consumption is reduced, but conversion with CMOS circuits requires complex signal conversions
Solution Approach 1:
The interface circuit dynamically changes signal parameters including voltage levels, pulse widths, and timing characteristics to translate between superconducting pulse logic and CMOS voltage logic. By adjusting these parameters in real-time, the circuit achieves efficient conversion without requiring complex architectural modifications to either the superconducting or CMOS sides.
3Speed
If data rates on superconductors are made very high, then processing speed is improved, but compatibility with typical clock speeds of test equipment deteriorates
Solution Approach 1:
The interface circuit employs periodic sampling and clocking mechanisms that synchronize high-speed superconducting data streams with lower-speed test equipment clock cycles. By using periodic capture registers and buffered storage, the system can accept high-rate incoming data and present it to test equipment at compatible lower rates without data loss.
Solution Approach 2:
Data is pre-processed, buffered, and synchronized in advance within the interface circuit before being presented to the test equipment. This preliminary action includes timing adjustment, level translation, and protocol conversion, ensuring that data is ready for acquisition at the exact moment the test equipment is ready to receive it, regardless of speed mismatches.
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
Facilitates accessible and cost-effective testing of superconducting logic circuits by bridging the gap between superconducting and CMOS interfaces, ensuring compatibility and efficient data transfer while maintaining high performance.
Implementation Method 1
One example superconducting circuit technique uses Josephson junctions, which are electrical devices in which two superconducting metals are separated by a thin layer of insulator, across which an electric current may flow in the absence of a potential difference. The current may be made to oscillate in proportion to an applied potential difference.
Implementation Method 2
Because superconductors have very little or no resistance, such circuits can be very fast and power efficient.
Data Source
AI summary
Embodiments of the present disclosure include techniques for interfacing with superconducting circuits and systems. In one embodiment, the present disclosure includes interface circuitry, including driver circuits and/or receiver circuits to send/receive signals with a superconducting circuit. In another embodiment, the present disclosure includes superconducting circuits and techniques for generating a trigger signal from and external clock that is based on a superconducting resonator. In yet another embodiment, the present disclosure includes superconducting data capture circuits that may be used to couple external data to and/or from superconducting logic.