Scan Warm-Up Circuit for Power Supply Voltage Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Testing complex functional circuits at speed using internal scan chains disrupts the power supply voltage, causing distortion and potential failure of circuits that operate according to specifications.
Innovation Solution
The implementation of a test circuit with a scan chain that includes a controller and scan cells, utilizing a warm-up phase to settle the power supply voltage by repetitively outputting and restoring test patterns, and using level-sensitive and edge-sensitive latches to manage the transition between scan and test modes, reducing power supply droop and ensuring accurate test results.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If test patterns are launched from internal scan chain at high speed, then testing speed is improved, but power supply voltage stability deteriorates
Solution Approach 1:
The patent applies preliminary action by performing a warm-up phase before actual testing. The controller repetitively outputs test patterns through the scan chain at high speed, then restores them, multiple times before conducting the actual test. This preliminary activity stabilizes the power supply voltage by pre-charging capacitive loads and establishing steady-state operating conditions, preventing voltage droop during the actual high-speed test operation.
2Stability of the object's composition
If scan operation shifts data serially at low speed, then power supply stability is maintained, but testing efficiency is reduced
Solution Approach 1:
The patent implements periodic action by alternating between two distinct phases: a warm-up phase where data is shifted through the scan chain at high speed with restoration operations, and an actual test phase. This periodic switching allows the system to achieve high-speed operation during the warm-up phase to stabilize power conditions, then maintain those stable conditions during the actual test phase, effectively combining the benefits of both high-speed and stable operation in a periodic cycle.
Data Source
AI summary
A test circuit for a functional circuit includes a scan chain coupled to the functional circuit, and a controller coupled to the scan chain, for controlling the scan chain to scan a test pattern into the scan chain, and subsequently and repetitively for a multiple number of times launch the test pattern to the functional circuit, capture test data into the scan chain, and restore the test pattern in the scan chain for subsequent launch.