Browse Prior Art Database

Charge Pump Circuit

IP.com Disclosure Number: IPCOM000082158D
Original Publication Date: 1974-Jun-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 2 page(s) / 48K

Publishing Venue

IBM

Related People

Terman, LM: AUTHOR

Abstract

This description relates to an improved charge pump circuit including the use of two plates, and the use of incomplete charge dumping to reduce the effect of surface states.

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Charge Pump Circuit

This description relates to an improved charge pump circuit including the use of two plates, and the use of incomplete charge dumping to reduce the effect of surface states.

Operation of a conventional charge pump circuit is shown in Fig. 1. A majority carrier flow-out of the diffusion is obtained by pulsing the plate above threshold, creating an inversion region under it. When the pulse terminates, most of the inversion layer charge flows back into the diffusion, but some fails to return, either due to trapping in the surface states under the plate, or incomplete charge transfer from too abrupt a pulse fall time. This charge is lost to the substrate, and represents a net flow of majority carriers out of the diffusion. This current is in opposite flow to leakage current, and can be used to compensate for it, for example, in a static memory cell. The current amplitude can be controlled by pulse amplitude and duty cycle.

The normal charge pump has the drawback that the current is also a function of the surface state density and pulse fall time; the former is in particular not easily controlled. The improved approach is shown in Fig. 2, and uses two plates. The two plates are pulsed on approximately simultaneously. (Actually, either may be pulsed on first, as long as the leakage current is negligible.) However, phi 1 is terminated first, trapping the charge under plate 1, so that when phi 2 terminates, all the charge under plate 2 is lost to the...