RSFQ Superconducting Lookup Table with Parallel Readout
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Solution Overview
Problem
There is a lack of fast programmable read-only memory (PROM) arrays and lookup tables in ultrafast superconducting digital circuits, particularly for applications requiring rapid data retrieval and infrequent updates, such as real-time digital predistortion of radio-frequency signals.
Innovation Solution
A digital lookup table circuit with a programmable read-only memory array and an n-bit address decoder using standard RSFQ elements, including non-destructive reset-set flip-flops and data flip-flops, enabling rapid parallel pipelined readout and slower serial reprogramming, designed for high-speed operation at a clock frequency of 20 GHz.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a superconducting RAM circuit is used, then fast data retrieval is achieved, but the architecture is not suitable for PROM-type applications requiring infrequent updates
Solution Approach 1:
The memory array is segmented into multiple rows and columns with independent address decoding capabilities, allowing selective access to specific memory locations while maintaining the ability to perform both rapid reading and serial writing operations
Solution Approach 2:
The memory architecture incorporates dynamic selection mechanisms where the same physical structure can operate in different modes: rapid parallel readout mode for PROM applications and serial reprogramming mode for updates, adapting to different operational requirements
2Adaptability or versatility
If a PROM architecture is implemented, then infrequent updates are supported, but fast data retrieval capability is compromised
Solution Approach 1:
The memory array is pre-programmed with lookup table data in a serial fashion, allowing the data to be ready for rapid parallel retrieval without requiring frequent updates, thus achieving both PROM functionality and fast readout performance
Solution Approach 2:
The memory structure maintains continuous readiness for rapid readout operations while incorporating periodic serial writing capability, ensuring that the useful action of fast data retrieval can continue uninterrupted between infrequent updates
3Adaptability or versatility
If serial reprogramming is used, then memory contents can be updated, but the update speed is slow compared to parallel readout
Solution Approach 1:
The memory array performs serial reprogramming operations periodically between rapid parallel readout cycles, accepting that updates are infrequent and can be performed sequentially without significantly impacting overall system performance
Solution Approach 2:
The memory structure incorporates self-contained writing mechanisms that can perform serial reprogramming autonomously without requiring complex parallel write control circuits, simplifying the update process despite the sequential nature of the operation
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
The solution provides a scalable, high-speed digital lookup table capable of 20 G words/sec, addressing the need for fast data retrieval and infrequent updates in digital signal processing applications.
Implementation Method 1
Ultrafast superconducting digital circuits are based on Josephson junctions integrated together according to RSFQ Logic
Data Source
AI summary
A high-speed lookup table is designed using Rapid Single Flux Quantum (RSFQ) logic elements and fabricated using superconducting integrated circuits. The lookup table is composed of an address decoder and a programmable read-only memory array (PROM). The memory array has rapid parallel pipelined readout and slower serial reprogramming of memory contents. The memory cells are constructed using standard non-destructive reset-set flip-flops (RSN cells) and data flip-flops (DFF cells). An n-bit address decoder is implemented in the same technology and closely integrated with the memory array to achieve high-speed operation as a lookup table. The circuit architecture is scalable to large two-dimensional data arrays.