Integrated Loopback Test Interconnect for DUT-Side Signal Integrity
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Solution Overview
Problem
Traditional test systems for packaged integrated circuits suffer from long loopback paths causing parasitic effects, signal degradation, interference, and poor power integrity, leading to voltage and current fluctuations that can damage the DUT, socket, and load board.
Innovation Solution
The system includes a DUT interface, load board interface, and integrated loopbacks with conductive paths and circuitized components to reduce resistive, capacitive, and inductive losses, enabling accurate DUT-side voltage measurement and improved power integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional testing sockets and load boards are used with external loopback circuits, then the DUT can be tested with standard equipment, but the loopback paths become long causing parasitic effects, signal degradation, and propagation delays
Solution Approach 1:
The patent merges the loopback circuit functionality directly into the test socket and load board structure. Specifically, the load board includes circuitry that provides loopback paths between signal contacts, eliminating the need for separate external loopback circuits. This integration reduces the loopback path length and associated parasitic effects while maintaining compatibility with standard testing equipment through the socket interface.
Solution Approach 2:
The patent introduces an intermediary structure - the integrated loopback circuitry within the load board - that mediates between the DUT and external testing equipment. This intermediary provides controlled impedance paths and reduces parasitic elements by keeping the loopback circuitry physically close to the socket, thereby improving signal quality without requiring changes to standard test equipment.
2Ease of manufacture
If voltage measurement is performed from the load board side of the socket, then measurement can be achieved with existing equipment, but the bandwidth is limited and voltage changes occur at the DUT due to spring probe parasitic losses
Solution Approach 1:
The patent segments the measurement function by providing separate measurement contacts on the load board that are electrically connected to specific signal contacts of the socket. This segmentation allows independent voltage measurement at different points in the circuit, enabling accurate DUT-side voltage measurement through dedicated measurement paths that bypass the parasitic losses of the spring probe power delivery paths.
Solution Approach 2:
The patent introduces intermediary measurement circuits on the load board that act as mediators between the socket and measurement equipment. These intermediary circuits provide high-impedance measurement paths that do not load the DUT, and they can measure voltage at points closer to the DUT than traditional load board measurements, thereby improving measurement precision while maintaining compatibility with existing measurement equipment.
3Device complexity
If traditional test sockets without integrated loopbacks are used, then the design is simpler, but power integrity suffers causing current fluctuations and voltage fluctuations that can damage the DUT, socket, and load board
Solution Approach 1:
The patent merges power delivery and signal transmission functions within the same socket and load board structure. The load board includes both signal contacts for DUT communication and integrated loopback circuitry that uses the same physical interface, thereby improving power integrity through reduced path lengths and controlled impedance designs without significantly increasing overall system complexity.
Solution Approach 2:
The patent changes the electrical parameters of the test interface by implementing controlled impedance traces and optimized ground connections on the load board. These parameter changes reduce parasitic inductance and resistance in the power and signal paths, thereby improving power integrity and reducing voltage and current fluctuations that could damage the DUT or test equipment.
Data Source
AI summary
Test interconnect systems and methods are described. In one example, a test interconnect includes. A device under test (DUT) interface for connecting to a DUT; a load board interface for connecting to a load board; a circuitized component including an integrated loopback for self-test or self-communication of the DUT; and one or more conductive paths for connecting the DUT to the load board.