Embedded Series Isolation Resistors for High-Speed ATE Signal Integrity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-speed signal testing of electronic devices, such as semiconductor memories, is hindered by parasitic capacitance causing signal reflections and poor quality, which limits the number of devices that can be tested in parallel due to transmission line effects like noise and interference.
Innovation Solution
Incorporating embedded series isolation resistors on a contactor board close to the input terminals of devices under test, formed as thin-film resistors on the board, to minimize reflections and noise, allowing a single tester channel to drive multiple devices effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single ATE signal channel is used to drive multiple DUT loads, then productivity increases, but signal quality deteriorates due to parasitic capacitance causing reflections
Solution Approach 1:
The patent divides the transmission line into multiple segments by placing isolation resistors at regular intervals along the trace. This segmentation isolates the capacitive loads of individual DUTs, preventing reflections from propagating along the entire transmission line. The resistors create electrical sections that can be independently managed, allowing multiple devices to be tested simultaneously without mutual interference.
Solution Approach 2:
The isolation resistors serve as intermediary elements between the transmission line and the DUT input terminals. These resistors act as buffer components that decouple the reflective effects of the DUT capacitance from the main transmission line, thereby protecting signal integrity while enabling multiple devices to share a single test channel.
2Ease of manufacture
If discrete surface mount resistors are used for isolation, then ease of manufacture improves, but device complexity increases due to additional stub lengths causing more reflections
Solution Approach 1:
The patent merges the isolation resistor function directly into the printed circuit board trace structure. Instead of using separate discrete components, the resistive elements are integrated as thin-film resistors deposited onto the PCB substrate. This integration eliminates the need for additional stub connections and reduces the overall number of discrete components, thereby improving signal quality while maintaining ease of manufacture.
Solution Approach 2:
The isolation resistors are implemented in a different dimensional approach by depositing thin-film resistive material directly onto the PCB trace layer. This allows the resistive function to be embedded within the plane of the circuit board rather than adding vertical complexity through discrete component mounting, thereby reducing stub lengths and reflections.
3Reliability
If series resistors are placed close to DUT input pins, then signal quality improves by minimizing reflections, but device complexity increases due to placement requirements
Solution Approach 1:
The isolation resistors are merged with the PCB trace structure itself, eliminating the need for separate discrete components to be placed near the DUT pins. The resistive function is integrated directly into the transmission line path on the circuit board, achieving close proximity to the DUT input terminals without adding placement complexity.
Solution Approach 2:
The isolation resistors are pre-configured and deposited onto the PCB during board fabrication, before final assembly. This preliminary integration ensures that the resistors are already in their optimal positions close to the DUT input terminals, eliminating the need for complex placement operations during assembly and reducing overall device complexity.
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 configuration significantly reduces signal reflections, enabling a single test signal to be shared among eight or more high-speed memory devices, enhancing parallel testing efficiency and reducing per-device testing costs by maintaining signal quality.
Implementation Method 1
Incorporating embedded series isolation resistors on a contactor board close to the input terminals of devices under test, formed as thin-film resistors on the board, to minimize reflections and noise
Data Source
Figure 1
Figure 2~3
Figure 4~5(b)
AI summary
Automated test equipment for high-speed testing of devices under test (DUTs) includes a tester channel circuit generating a high-speed electrical test signal applied to the signal input terminal of each DUT, and a contacter board in physical and electrical contact with the DUTs. The contacter board has a high-speed signal transmission channel including (1) an electrical contact at which the high-speed electrical test signal is received, (2) conductive etch extending from the electrical contact to isolation areas each adjacent to the signal input terminal of a respective DUT, and (3) an embedded series isolation resistor formed on an inner layer of the contacter board at a respective isolation area forming a connection between the conductive etch and the adjacent signal input terminal of the respective DUT.