Semiconductor Testing Apparatus With Switching Circuit For Pad Sharing

The patent implements a switching circuit that allows a small number of test pads to be dynamically shared among multiple test units. The switching circuit routes test signals from limited test pads to different test units based on control signals, enabling one test pad to serve multiple test units sequentially. This multi-functional approach resolves the contradiction by maintaining high testing capability while minimizing the number of physical test pads required on the chip.

The patent introduces a switching circuit as an intermediary between the test pads and test units. This switching circuit manages the complex connections between multiple test units and limited test pads, simplifying the overall system architecture. The switching circuit receives control signals and dynamically connects appropriate test units to test pads, enabling efficient testing of multiple units without requiring proportional increases in test pad infrastructure.

The patent extracts and compensates for parasitic leakage effects by implementing a forcing-sensing scheme. Separate forcing pads apply test signals while dedicated sensing pads measure the actual signals received by test units. This separation allows the system to distinguish between genuine test unit responses and parasitic leakage currents, thereby maintaining measurement precision even with minimal test pads on the chip.