Rigid PCB Signal Routing for Low-Noise Cryogenic Measurements
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Solution Overview
Problem
Mechanical vibrations in cryostats cause significant electrical noise on signal lines, particularly at low frequencies, affecting measurements and control operations in low-temperature environments, especially in non-uniform magnetic fields, which is a challenge for scalable quantum computing and sensing applications.
Innovation Solution
Routed low-frequency signal lines in a dilution refrigerator using rigid printed circuit boards (PCBs) with tight spacing and avoided flexible cables in high magnetic field regions, minimizing mechanical vibrations and electromagnetic interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If flexible cables are used for signal lines in low temperature environments, then ease of connection and adaptability are improved, but mechanical vibrations cause significant electrical noise particularly at low frequencies
Solution Approach 1:
The patent replaces flexible mechanical cable connections with rigid printed circuit board (PCB) trace connections. The PCB provides a solid, vibration-resistant mechanical structure that eliminates the flapping and movement of flexible cables, thereby reducing mechanical vibrations that cause electrical noise in non-uniform magnetic fields while maintaining electrical connectivity.
Solution Approach 2:
The patent uses composite construction by integrating signal lines directly into the PCB substrate, combining the structural stability of the rigid PCB material with the electrical conductivity requirements. This composite approach creates a unified structure that is inherently resistant to vibration-induced noise while providing reliable electrical connections.
2Adaptability or versatility
If signal lines are routed through non-uniform magnetic field regions, then connectivity between sample holder and external interface is maintained, but vibration-induced electrical noise increases
Solution Approach 1:
The patent replaces flexible cable routing with rigid PCB trace routing through the non-uniform magnetic field region. The rigid PCB structure resists mechanical vibrations that would otherwise cause the flexible cables to move and flap, thereby reducing the generation of electrical noise while maintaining the necessary electrical connectivity through the magnetic field region.
Solution Approach 2:
The patent applies local quality by making the signal lines rigid and fixed in the specific region where they pass through the non-uniform magnetic field, while allowing flexibility elsewhere in the system. This localized rigidity in the critical magnetic field region minimizes vibration-induced noise where it matters most, while maintaining overall system adaptability.
3Object-affected harmful factors
If rigid printed circuit boards are used for signal lines, then vibration-induced electrical noise is reduced, but device complexity increases
Solution Approach 1:
The patent merges the signal line function with the structural PCB substrate. Instead of having separate flexible cables for signal transmission, the signal lines are integrated directly into the PCB traces, combining multiple functions (structural support, signal routing, vibration resistance) into a single unified component, thereby reducing overall device complexity despite the rigid construction.
Solution Approach 2:
The PCB serves multiple functions simultaneously: it provides mechanical support for the sample holder, routes electrical signals, and acts as a vibration-resistant structure in the magnetic field region. This multi-functionality reduces the need for separate components, thereby managing device complexity while achieving noise reduction.
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
Reduces vibration-induced electrical noise, allowing faster measurements and improved signal-to-noise ratios, essential for scalable quantum devices.
Implementation Method 1
Mechanical vibrations in cryostats cause significant electrical noise on signal lines, particularly at low frequencies
Implementation Method 2
Printed signal lines on the rigid PCB extend between a sample holder and an external interface
Data Source
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AI summary
Electrical communication between a sample (such as a quantum chip, semiconductor sample etc.) in a low temperature environment and an external device is effected via signal lines printed on rigid printed circuit board (PCB) located within a region of the low temperature environment (e.g., a non-uniform magnetic field region). One example application is performing a measurement of an electrical property of the sample at a low signal frequency with a short measurement integration time, although the subject matter is not limited in this respect. Another application is routing an electrical control signal to the sample.