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Tester for Capacitor or FET Gate Structure with Ramp Voltage

IP.com Disclosure Number: IPCOM000085078D
Original Publication Date: 1976-Feb-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Anolick, ES: AUTHOR [+2]

Abstract

A capacitor, such as the gate structure of a field-effect transistor (FET) is advantageously tested by a ramp voltage that rises at a slow rate, such as 55 volts in 100 seconds. For testing high-production quantities, test subject 2 comprises several capacitors that each have one terminal connected in common to a line 3 to receive a ramp voltage waveform and have their other electrode connected to individual probes 4. Each probe 4 is connected in circuit with contacts 5 of a relay and with two voltage dividing resistors 7, 8.

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Tester for Capacitor or FET Gate Structure with Ramp Voltage

A capacitor, such as the gate structure of a field-effect transistor (FET) is advantageously tested by a ramp voltage that rises at a slow rate, such as 55 volts in 100 seconds. For testing high-production quantities, test subject 2 comprises several capacitors that each have one terminal connected in common to a line 3 to receive a ramp voltage waveform and have their other electrode connected to individual probes 4. Each probe 4 is connected in circuit with contacts 5 of a relay and with two voltage dividing resistors 7, 8.

When a breakdown occurs in a capacitor that is connected to the circuit, an increased current flows in the circuit of resistors 7 and 8 and a voltage appears at their common connection point. Components that are shown in the drawing detect this condition, operate relay coil 6 to open the circuit of a trailing capacitor, and operate a counter 9 to count the number of failures during the test. Zener diodes 10 and 11 limit the voltage across resistors 7 and 8 during these operations.

The circuit of transistors 12 and 13 and diodes 14, 15 and 16 detects the voltage at the common connection point of resistors 7 and 8, when the associated capacitor of test subject 2 breaks down and current flows in resistors 7 and 8. Transistor 13 is normally turned on by base current in the circuit of diode 16 and a resistor 17. When a negative voltage ramp is used for the test, a fault turns on diode 1...