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Regeneration Circuit for Charge Coupled Device Shift Registers

IP.com Disclosure Number: IPCOM000076990D
Original Publication Date: 1972-May-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Dennard, RH: AUTHOR

Abstract

The solid line portion of the circuit shown in Fig. 1 is a sense amplifier for charge-coupled device shift registers, which has been discussed recently in some detail.[1-3]

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Regeneration Circuit for Charge Coupled Device Shift Registers

The solid line portion of the circuit shown in Fig. 1 is a sense amplifier for charge-coupled device shift registers, which has been discussed recently in some detail.[1-3]

It is generally recognized to be very desirable to transmit a small amount of charge even in the "0" state, approximately one-tenth of the value which is transmitted in the "1" state. (This has been called a "fat zero."). This keeps the surface always biased in a given direction, so that a transition from a long string of 0's to a long string of 1's will not cause the first bit to lose some of its charge to surface states at each storage location. A straightforward implementation of a regeneration circuit to launch "fat zero's" can consume a great deal of space, and space is at a premium in the integrated circuit environment. It has been found, however, that a "fat zero" can be obtained by introducing a diffusion, as indicated by the dashed lines in Fig. 1, with some capacitance Co to ground or to any fixed potential. The diffusion can also be thought of as a drain of a device and the regeneration circuit represented, as shown in Fig. 2, with the capacitance Co connected to ground or any other desired fixed potential.

It should be recognized that the regeneration circuit is actually an inverter, so that any 0 transmitted in the second register corresponds to a 1 received in the first register. The circuits shown cause "fat zero's"...