| 摘要 |
A technique for detecting whether electrical contact between a probe tip and a device under test ("DUT") has been established. A contact sensing circuit has a ground that is isolated from the ground of the DUT (and remaining portions of the test equipment) during contact sensing. The contact sensing circuit has elements that operate to apply a characteristic signal to one of the DUT terminals, such as its ground terminal. This causes virtually all the DUT circuit traces to track the applied signal (relative to the contact sensing ground). The contact sensing circuit further includes elements, coupled to the probe, that operate to detect the presence of the characteristic signal (relative to the contact sensing ground) on the probe. Once electrical contact has been established, the characteristic signal output is disconnected from the DUT, the test equipment ground is connected to the contact sensing circuit ground, and the probe output is coupled to the relevant portions of the test equipment circuitry.
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