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Browse Prior Art Database

Bootstrap Push Pull Driver

IP.com Disclosure Number: IPCOM000083874D
Original Publication Date: 1975-Aug-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Chu, WM: AUTHOR [+2]

Abstract

This circuit provides compatible uplevel signals for internal circuits, with a single positive power supply.

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Bootstrap Push Pull Driver

This circuit provides compatible uplevel signals for internal circuits, with a single positive power supply.

Fig. 1 is a bootstrap push-pull driver, which offers high uplevels that cannot be obtained using conventional push-pull drivers. When circuit dotting is not needed, because of its high uplevel, this driver has the advantage of not requiring a special receiver.

The bootstrap push-pull driver has three stages. Stages I and II are regular inverter circuits. Push-pull stage III consists of compatible pull-up and push- down devices plus capacitor CD (between points D and E) and depletion device
8. Capacitor CB acts as a bootstrap and device 8 is used to maintain the output stage leakage current. Connected between stages I, II, and III is device 7, which acts as a diode.

As shown in Fig. 2, when input A drops from an uplevel to a downlevel, point B rises from a downlevel to an uplevel with some delay. Point B is further delayed by stage II whose output is C. Before C can fall to its downlevel and before E rises during the charging time (t), device 7 is on and current conducts from B to D, charging capacitor CB to a relatively high level.

The voltage at point D closely follows point B until it almost reaches the maximum uplevel (VDD). Most of the charge on CB remains, applying a minimum of 2.4 V to VCB, which turns on device 5, charging output load CL to an uplevel (approximately VDD). When the output reaches VDD, device 8 maintains the...