Method and apparatus for characterizing test elements on the basis of rise-time degradation

Claim 1

In a system for determining the dynamic input impedance of a rectifying semiconductor junction by measuring the rise time degradation of an input pulse comprising the steps of: connecting said semiconductor at a test node, delivering reference fast rise time pulses by way of a first transmission line to said test node, simultaneously delivering said reference pulses by way of a second and identical transmission line to a reference node, sensing the pulse signal at said reference node, said reference node pulse signal being substantially identical to the reference pulse, simultaneously sensing the pulse signal at said test node, said pulse signal at the test node being different from said reference pulse due to rise time degradation caused by said semiconductor connected at said test node whereby the pulse signal at the test node is a composite signal of incident and delayed reflected pulse wave components, comparing the pulse signals at the reference and test nodes to determine delay in the composite incident and reflected component pulse signal at the test node as a result of rise time degradation caused by said semiconductor junction, and characterizing the semiconductor under test on the basis of its dynamic input impedance as indicated by the delay.