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Analog Voltage Storage with Storage Protection

IP.com Disclosure Number: IPCOM000093345D
Original Publication Date: 1967-Aug-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Walton, CA: AUTHOR

Abstract

This circuit protects the charge stored in a capacitor in the event of power failure. The voltage of source 10 is applied by storing junction field effect transistor JFET 12 to storage capacitor 14 to store a proportionate charge in it for use in further circuitry. Normally, JFET 12 has a gate voltage applied at terminal 16 maintaining a high resistance between source and drain electrodes. When the charge is to be stored, the gate voltage is lowered to present a low resistance in the circuit path between source 10 and capacitor 14. In the event of power failure, the gate voltage is lowered and the stored charge is dissipated across source 10 through the lowered resistance between the source and drain electrodes of JFET 12.

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Analog Voltage Storage with Storage Protection

This circuit protects the charge stored in a capacitor in the event of power failure. The voltage of source 10 is applied by storing junction field effect transistor JFET 12 to storage capacitor 14 to store a proportionate charge in it for use in further circuitry. Normally, JFET 12 has a gate voltage applied at terminal 16 maintaining a high resistance between source and drain electrodes. When the charge is to be stored, the gate voltage is lowered to present a low resistance in the circuit path between source 10 and capacitor 14. In the event of power failure, the gate voltage is lowered and the stored charge is dissipated across source 10 through the lowered resistance between the source and drain electrodes of JFET 12.

Holding capacitor 18 is charged during normal operation through diode 20 and a voltage divider comprising resistors 22 and 24 connected across a source of potential. Capacitor 18 is connected to the source electrode of holding JFET
26. The drain electrode of JFET 26 is connected to the gate electrode of JFET
12. The gate electrode of JFET 26 is connected to the source of potential by diode 28 to maintain a high resistance normally between capacitor 18 and the gate electrode of JFET 12.

In the event of power failure, the energizing potential falls permitting JFET 26 to present a low resistance between capacitor 18 and JFET 12. The charge on capacitor 18 maintains a high resistance between the JFET 1...