Superconducting IC Routing with Different-Layer JTLs
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Solution Overview
Problem
Existing superconducting integrated circuits face challenges with the Josephson transmission line (JTL) being inconducive to routing, leading to increased circuit area occupation and difficulties in impedance matching at high frequencies, which limits circuit speed and yield.
Innovation Solution
A superconducting integrated circuit design method using different-layer JTLs, where transverse and longitudinal JTL routing layers are separated from the logic cell layer, allowing for convenient cross-routing by using vias and maintaining high-speed circuit performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If JTL is used for signal transmission, then signal transmission integrity is ensured, but routing becomes inconvenient and circuit area increases
Solution Approach 1:
The patent introduces a third dimension by stacking multiple JTL layers vertically. Routing can now occur in different layers, allowing signals to route around obstacles and connect to distant cells without crossing other signals, thus improving routing convenience while maintaining signal integrity through the inherent properties of JTL
2Speed
If micro-strip line is used for transmission, then transmission speed is high, but impedance matching becomes difficult at high frequency
Solution Approach 1:
The patent changes the fundamental transmission mechanism from micro-strip line to JTL, altering the physical parameters of signal transmission. JTL uses Josephson junctions to generate and transmit voltage pulses, which naturally provide impedance matching and maintain signal integrity at high frequencies while achieving transmission speeds suitable for superconducting circuits
3Speed
If PTL is used for long-distance transmission, then transmission speed is high, but excessive area occupation occurs due to additional drivers and receivers
Solution Approach 1:
The patent makes JTL multi-functional by enabling it to serve both as a signal transmission medium and as a routing structure. The same JTL infrastructure can be used for both vertical and horizontal routing across different layers, eliminating the need for separate driver and receiver circuits at each interface, thus reducing circuit area while maintaining high transmission speed
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 overcomes the limitations of JTLs in routing, enhances circuit yield, and lays a foundation for future automatic placement and routing, while maintaining high-speed performance and reducing circuit area.
Implementation Method 1
The JTL is a cell composed of Josephson junctions connected through inductors and is widely used in circuits since signal transmission integrity is ensured by the junctions triggered in sequence when the signal is transmitted through the cell
Implementation Method 2
Superconducting integrated circuits refer to integrated circuits based on Josephson junctions and superconducting materials and including applications such as single-flux-quantum (SFQ) circuits
Data Source
AI summary
A superconducting integrated circuit design method based on placement and routing by different-layer JTLs comprises: cutting a bias line at a cell data interface of a cell library, and reserving a position of a via; placing and arranging cells on a logic cell layer according to a schematic circuit logic diagram; connecting clock lines of each of the cells by using a JTL and a splitter of the logic cell layer; and performing data connection on each of the cells by using JTLs of a transverse JTL routing layer and a longitudinal JTL routing layer which are not in the same layer as the logic cell layer, wherein the JTL of the transverse JTL routing layer is used as a transverse routing cell for data between the cells, the JTL of the longitudinal JTL routing layer is used as a longitudinal routing cell for data between the cells.