Browse Prior Art Database

Germanium Tunnel Diode Memory Cell

IP.com Disclosure Number: IPCOM000036870D
Original Publication Date: 1989-Nov-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 4 page(s) / 80K

Publishing Venue

IBM

Related People

Swietek, D: AUTHOR

Abstract

A germanium tunnel diode storage cell has been proposed for use in semiconductor devices which employs one tunnel diode, one resistor, and three transistors.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 55% of the total text.

Page 1 of 4

Germanium Tunnel Diode Memory Cell

A germanium tunnel diode storage cell has been proposed for use in semiconductor devices which employs one tunnel diode, one resistor, and three transistors.

In developing the proposal a model of a tunnel diode was formulated which includes the current which is due to the direct tunneling effect of germanium plus excess currents caused by indirect tunneling and the normal diode thermal current. A plot of this curve is given in Fig. 1, which shows two stable operating points (A and B) separated by the negative resistance portion of the curve.

The circuitry of Fig. 2 capitalizes on the foregoing by using a complementary push-pull current scheme to switch the tunnel diode quickly between these points while maintaining a very low standby current. The push-pull devices are QW0 and QW1 while QR is the sense device. Resistor Rs is of a high value used to supply the standby current, approximately 6 ma in this case. By applying an appropriate bias to the bit lines WX and WY in the waveform in Fig. 2, a one or a zero is written in the diode as follows: Writing a "1":

(Image Omitted)

QW1 will be turned on by bit line Wx being raised to a +0.8 while bit line Wy is also raised to +0.8 V. A diode that is sitting at point "A" of Fig. 1 now sees sufficient current to rapidly move to the other stable operating point "B". The bit lines can then return to their non-select values of -0.1 V.

Writing a "0": QW0 will be turned on by bit line Wx being lowered to -1.5 V and bit line Wy being lowered to -0.8 V. The cathode of the standby current supplied by Rs is now shunted through QW0, resulting in the operating point of the diode moving from "B" to "A...