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Measurement of Tunnel Diode Peak and Valley Characteristics

IP.com Disclosure Number: IPCOM000091297D
Original Publication Date: 1968-Jan-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Related People

Bannon, DW: AUTHOR

Abstract

The circuitry is for high-speed automatic testing of tunnel diode characteristics. The stability requirements of conventional DC biasing methods for keeping loop impedances less than the negative resistance of the diode are eliminated. The current through the diode under test DUT 1 is varied until the device switches from one state to another. The change in voltage level is detected and used to gate sample-and-hold circuit 2. The latter tracks either the voltage across DUT 1 or the input to current driver 3 where the input is proportional to the diode current. Ramp generator 4 applies a time-varying voltage to driver 3 whose output current is proportional to the input voltage.

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Measurement of Tunnel Diode Peak and Valley Characteristics

The circuitry is for high-speed automatic testing of tunnel diode characteristics. The stability requirements of conventional DC biasing methods for keeping loop impedances less than the negative resistance of the diode are eliminated. The current through the diode under test DUT 1 is varied until the device switches from one state to another. The change in voltage level is detected and used to gate sample-and-hold circuit 2. The latter tracks either the voltage across DUT 1 or the input to current driver 3 where the input is proportional to the diode current. Ramp generator 4 applies a time-varying voltage to driver 3 whose output current is proportional to the input voltage.

As the current is increased to the peak point, DUT 1 switches from the low to the high forward state. The change in voltage level is detected by level detector
5. The latter sends a signal to control logic 6 which responds with a hold command to circuit 2. The response of circuit 2 is very slow so that the hold command is received and completed before the circuit can respond to the change at the input. In this manner, circuit 2 stores the signal level attained at the time DUT 1 switches, which can be either the peak voltage or current.

To measure the valley point parameters, DUT 1 is first biased in the high forward state and then the generator 4 output is decreased to thus decrease the diode current. As the current is decreased to...