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US 5,861,743 AGranted
Hybrid scanner for use in an improved MDA tester
AssigneeGenRad, Inc.
InventorsRichard Pye, Moses Khazam
Life of this patent
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AssigneeGenRad, Inc.
InventorsRichard Pye, Moses Khazam
Estimating the term…
A hybrid scanner for switching internal analog buses to system pin channels. Semiconductor switches switch most scanner buses to system pin channels, but mechanical relays perform switching for at least one bus used for high-current test signals. To perform low-impedance guarding and/or high-current backdriving, the low impedance, high current bus is typically connectable to one or more overdriver circuits and a guard voltage potential through mechanical relays. The scanner is capable of supporting in-circuit tests covering the most significant regions of the fault spectrum can be made more reliable and much smaller and less costly than the scanners conventionally used in traditional broad spectrum testers. It turns out that this test-supporting capability can be achieved by adding only a few mechanical relays to an otherwise semiconductor-switch-based scanner. Only those necessary to support low-impedance and high-current test operations.
An automatic circuit tester comprising:
In an automatic circuit tester comprising analog instruments, a scanner adapted for coupling an electronic-circuit board thereto and comprising a switch matrix that includes matrix switches, and a control circuit for operating the matrix switches to complete stimulus, sense, and guard paths through the switch matrix and for making analog measurements by so operating the analog instruments as to apply an electrical stimulus signal to the circuit board through the stimulus path and sense a resultant electrical response on the circuit board through the sense path while guarding a guard node on the circuit board through a guard path, the improvement wherein:
In the method of automatic circuit testing comprising the steps of coupling to an electronic-circuit board a switch matrix that includes matrix switches, operating the matrix switches to complete stimulus, sense, and guard paths through the switch matrix, and making an analog measurement by applying an electrical stimulus signal to the circuit board through the stimulus path and sensing a resultant electrical response on the circuit board through the sense path while guarding a guard node on the circuit board through a guard path, the improvement wherein:
Dependencies are inferred from the claim text.