Browse Prior Art Database

Threshold Detector

IP.com Disclosure Number: IPCOM000094606D
Original Publication Date: 1965-Mar-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Crawford, DJ: AUTHOR

Abstract

This is a gated threshold detector with a feedback calibration circuit for maintaining the threshold element at a desired point of operation.

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Threshold Detector

This is a gated threshold detector with a feedback calibration circuit for maintaining the threshold element at a desired point of operation.

The main element of the circuit is tunnel diode 10. This is normally biased to a sufficiently low level to be insensitive to input signal source 12. The application of a threshold set level to terminal 14 biases diode 10 near its peak current. The simultaneous application of an input signal above a critical value from source 12 acts to impulse diode 10 to its high-voltage state, producing an output signal. At the termination of the cycle, a reset signal is applied via resistor 16 and causes diode 10 to revert back to its low-voltage state. Likewise, signal source 12 and threshold set 14 fall to a quiescent level. The quiescent level of signal source 12 is used as an absolute reference point from which to calibrate diode 10.

After the above operation, threshold set 14 is re-energized and a calibrate pulse is applied to And's 20 and 22. Assuming that the application or threshold set 14 does not set diode 10 to its high-voltage state, the level on line 24 to And 20 is at the low-voltage level. The output of And 20 is likewise at a down level, causing inverter 26 to have an up output. This up output in combination with the calibrate pulse fully conditions And 22. This produces a pulse of current through diode 28 which adds to the charge level of capacitor 30. This results in a slightly increased conduction in...