Multi-Injector Flux-Pump DAC for Faster Flux Loading
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing superconducting circuits face challenges in efficiently introducing flux into integrated circuits (ICs) due to spatial and thermal constraints, leading to impracticality in directly probing flux at various points on the IC, which affects power consumption and magnetic field generation.
Innovation Solution
A flux-pump DAC with multi-flux quantum injection is employed, utilizing a ring of Josephson transmission line stages and multiple injector JJs to introduce multiple flux quanta in a single AC clock cycle, allowing controlled flux storage and distribution to RQL circuits without increasing clock speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple flux quanta are injected into the ring in a single AC clock cycle, then the flux loading speed into the load inductor is increased, but the device complexity increases due to multiple injector JJs
Solution Approach 1:
The flux injection function is segmented into multiple independent injector JJs distributed around the ring. Each injector JJ can be independently controlled to inject flux quanta at different locations, enabling parallel flux injection that increases loading speed while maintaining modular complexity
Solution Approach 2:
The patent transitions from sequential flux injection (single injector, one flux quantum per clock cycle) to parallel flux injection (multiple injectors, multiple flux quanta per clock cycle). This adds a spatial dimension to the injection process, allowing simultaneous injection events at different ring locations, effectively increasing productivity without proportionally increasing device complexity
2Temperature
If flux is rapidly loaded and unloaded from the load inductor, then thermal link issues are reduced, but the precision of flux control becomes more challenging
Solution Approach 1:
The system employs feedback control where the state of the load inductor is monitored and used to regulate the flux injection process. This allows rapid flux loading/unloading while maintaining precision through real-time adjustments, resolving the contradiction between speed and control accuracy
Solution Approach 2:
The flux injection is performed in periodic cycles synchronized with the AC clock, allowing the system to achieve rapid flux changes while maintaining precise control through regular, predictable timing. The periodic nature enables thermal management while preserving flux quantization accuracy
3Stability of the object's composition
If DC bias is provided directly using a bias resistor network, then the JJ bias is stable, but the power dissipation and magnetic fields become substantially high
Solution Approach 1:
The patent replaces the DC bias resistor network (electrical/thermal system) with an AC clocked flux pump system. This substitution eliminates the continuous power dissipation associated with DC bias resistors while maintaining JJ bias stability through the superconducting flux pump mechanism, which operates with minimal energy loss in the superconducting state
Solution Approach 2:
The system exploits the superconducting phase transition to achieve low-resistance operation. By operating the flux pump and JJs in the superconducting state, the system maintains stable bias conditions with negligible power dissipation, contrasting with the resistive DC bias approach that operates in the normal conducting state with high power loss
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 enables faster flux loading and unloading in the load inductor, reducing thermal link issues and improving power efficiency by allowing precise control over flux accumulation, thus enhancing the functionality of RQL systems.
Implementation Method 1
The load inductor is configured to store the flux injected into the ring
Implementation Method 2
a first quantum of magnetic flux is injected into a Josephson transmission line ring of a flux pump via a first injector in the Josephson transmission line ring
Data Source
AI summary
A flux-pump digital-to-analog converter (DAC) includes a ring of Josephson transmission line (JTL) stages. The ring includes multiple injector Josephson junctions (JJs). Each of the multiple injector JJs can be individually activated to inject magnetic flux into the ring in a given AC clock cycle, or controllably deactivated so as not to inject flux during the given AC clock cycle. The flux-pump DAC further includes a load inductor coupled to ring JJs of the ring. The load inductor is configured to store the magnetic flux injected into the ring. Because the flux-pump DAC includes multiple injector JJs arranged around the JTL ring, it can ramp up current loaded into the load inductor faster than a single-injector flux-pump DAC, and with precise, variable controllability of ramp speed so as to provide enhanced adiabaticity.