Browse Prior Art Database

Driver with Speed Up Transistor

IP.com Disclosure Number: IPCOM000089880D
Original Publication Date: 1968-Dec-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 25K

Publishing Venue

IBM

Related People

Donofrio, NM: AUTHOR [+2]

Abstract

Transistor Q2 shunts resistor R1 to provide a fast negative transition at the output of the circuit. As the input to transistor Q1 goes from its down level to its up level, the change in voltage at point A produces current through the collector-base capacitance of Q2. This current acts as base current to Q2 and turns Q2 on. In turn, Q2 allows transistor Q3 to turn on and saturate quickly thus providing a very fast negative transition at the output. Resistor R4 is used to keep Q2 slightly on while the input at Q1 is up. Since R4 has a high value, it prevents Q2 from affecting the biasing network provided by resistors R1 and R2 and diode D1 which is essential for keeping Q3 off when the input of Q1 is down.

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 100% of the total text.

Page 1 of 2

Driver with Speed Up Transistor

Transistor Q2 shunts resistor R1 to provide a fast negative transition at the output of the circuit. As the input to transistor Q1 goes from its down level to its up level, the change in voltage at point A produces current through the collector-base capacitance of Q2. This current acts as base current to Q2 and turns Q2 on. In turn, Q2 allows transistor Q3 to turn on and saturate quickly thus providing a very fast negative transition at the output.

Resistor R4 is used to keep Q2 slightly on while the input at Q1 is up. Since R4 has a high value, it prevents Q2 from affecting the biasing network provided by resistors R1 and R2 and diode D1 which is essential for keeping Q3 off when the input of Q1 is down.

1

Page 2 of 2

2

[This page contains 3 pictures or other non-text objects]