Programmable Logic Feedback Routing for Test Signal Round-Trip Timing
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Solution Overview
Problem
Conventional semiconductor test devices face challenges in measuring round-trip time of test signals without additional devices or physical bus lines, especially when the Device Under Test (DUT) is not connected, which limits accurate testing and parameter setting.
Innovation Solution
An apparatus utilizing a programmable logic device with bidirectional bus lines and output/input buffers to measure round-trip time by routing test signals through internal circuits, allowing feedback without additional physical connections, even when the DUT is absent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional devices or bus lines are used to measure round-trip time, then measurement capability is improved, but device complexity increases
Solution Approach 1:
The pattern generator uses its own output buffers and input buffers to create a feedback loop for the test signal. The signal travels through the bidirectional bus lines and is routed back to the pattern generator without requiring external measurement devices, enabling self-measurement of round-trip time
Solution Approach 2:
The bidirectional bus lines serve dual purposes: they transmit test signals to the DUT during normal testing and simultaneously serve as the measurement path for round-trip time detection. The output buffers and input buffers are used both for signal transmission and for timing measurement
2Adaptability or versatility
If DUT is not connected to bidirectional bus lines, then testing flexibility is improved, but feedback signal reception becomes impossible
Solution Approach 1:
The programmable logic device acts as an intermediary that routes the test signal from the output buffers through the bidirectional bus lines and back to the input buffers when no DUT is connected. This intermediary routing mechanism maintains the feedback loop functionality regardless of DUT connection status
Solution Approach 2:
The system dynamically adapts its signal path based on DUT connection status. When DUT is connected, the signal flows through the DUT; when DUT is absent, the programmable logic device dynamically routes the signal through alternative paths within itself to maintain the feedback loop
Data Source
AI summary
An apparatus for measuring round-trip time of a test signal using a programmable logic device comprises a pattern generator generating a test signal and measuring a round-trip time of the test signal, a programmable logic device of which internal circuits are configured to transmit the test signal in a predetermined manner, and bidirectional bus lines connecting the pattern generator and the programmable logic device. The round-trip time of the test signal is measured by a time difference between a starting time at which the pattern generator outputs the test signal and an arrival time at which the test signal is fed back to the pattern generator.