Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

Clock Driver for Integrated Circuit Loads

IP.com Disclosure Number: IPCOM000087138D
Original Publication Date: 1976-Dec-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 3 page(s) / 35K

Publishing Venue

IBM

Related People

McDowell, JR: AUTHOR [+2]

Abstract

A current-limited sink drives this circuit to provide a constant current source to charge a capacitive load to an internally generated up level and to discharge it to a down level. This circuit is designed to minimize component count and power dissipation for integrated circuit design.

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 54% of the total text.

Page 1 of 3

Clock Driver for Integrated Circuit Loads

A current-limited sink drives this circuit to provide a constant current source to charge a capacitive load to an internally generated up level and to discharge it to a down level. This circuit is designed to minimize component count and power dissipation for integrated circuit design.

When Icl is on, it sinks the base drive of T1, turning T1 off. This allows the collector of T1 to rise, turning D1, T2 and T3 on. Functionally, T2 sinks the current from T1, turning T4, the up-level driver, off. T3 is the down-level driver. Current limiting occurs when the voltage drop across R1 is sufficient to force the bases of T2 and T3 to exceed the clamp voltage determined by D1 and T1, which shunts the excess base drive away from T2 and T3. D1 also prevents the base of T1 from going below Vee.

When Icl is off, T1 turns on, turning T2 and T3 off. This allows T1 to drive T4 on, providing the up-level drive. The up-level drive current is limited when the voltage drop across R2 exceeds the threshold voltage of T5, which shunts the excess base drive around T4. T6 and Z1 clamp the output voltage by shunting all the base drive around T4.

The power dissipation is minimized by turning off the drivers when the load is in steady state. The normal power dissipation is approximately the power dissipated in R3 and R4, plus the product of T1 and Vcc-Vee, the power supply drop. The power may be further minimized by tying R3 and R4 to a voltage lower than Vcc...