Source Driver Charge-Sharing Test Circuit
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High voltage stress tests on source drivers with numerous output pads require a large number of probes, increasing the cost and complexity of the test machine.
Innovation Solution
A source driver circuit incorporating charge-sharing paths and switches that allow for selective coupling of test voltages during test periods, enabling electrical tests without interfering with normal charge-sharing operations, thus reducing the number of probes needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large number of probes are used to perform HVS test on numerous output pads, then test coverage is improved, but test machine cost increases
Solution Approach 1:
Multiple output pads are electrically connected to a single common test pad through the charge-sharing paths. During test mode, the charge-sharing switches connect multiple output pads to the common test pad, allowing a single probe to simultaneously test multiple output pads. This merging approach reduces the number of probes required from many individual probes to just one or two probes, thereby reducing test machine cost while maintaining comprehensive test coverage.
Solution Approach 2:
The charge-sharing paths, originally designed for their primary function of charge sharing during normal operation, are made multi-functional by enabling them to serve as test signal transmission paths during test mode. The same charge-sharing paths that distribute charge to multiple output pads during operation are repurposed to convey test signals from a single common test pad to multiple output pads during testing, achieving universal utilization of the circuit structures.
2Reliability
If test voltages are applied to output pads during test period, then electrical testing is enabled, but charge-sharing operation may be interfered with
Solution Approach 1:
The source driver operates in periodic cycles, alternating between normal operation mode and test mode. During normal operation mode, the charge-sharing switches are in a first state that enables charge-sharing paths to function for their primary purpose. During test mode, the switches transition to a second state that redirects the charge-sharing paths for test signal transmission. This periodic switching between modes ensures that test voltages are applied only during designated test periods, preventing interference with charge-sharing operations during normal operation.
Solution Approach 2:
The charge-sharing switches are made dynamically controllable, allowing their state to be changed based on operational requirements. The switches can be controlled to connect output pads to charge-sharing paths during normal operation, and to connect the common test pad to charge-sharing paths during test mode. This dynamic reconfiguration enables the same circuit structures to adaptively serve different functions at different times, resolving the conflict between testing and charge-sharing operations.
Data Source
AI summary
A source driver includes a first output pad, a second output pad, a first charge-sharing path, a second charge-sharing path, a first charge-sharing switch, a second charge-sharing switch and a test circuit. A first terminal and a second terminal of the first charge-sharing switch are respectively coupled to the first output pad and the first charge-sharing path. A first terminal and a second terminal of the second charge-sharing switch are respectively coupled to the second output pad and the second charge-sharing path. The test circuit is coupled to the first charge-sharing path and the second charge-sharing path. The test circuit performs a test for the first output pad and the second output pad via the first charge-sharing path, the second charge-sharing path, the first charge-sharing switch and the second charge-sharing switch in a test period.