Load Programmable Off-Chip Driver
Original Publication Date: 1987-Jul-01
Included in the Prior Art Database: 2005-Feb-01
Load capacitance is programmed into off-chip drivers (OCDs) before or after a chip is designed and placed, such that proper drive is selected to minimize clock skew. Thus, a user may place an OCD of a single design at any point on a card and supply needed capability to drive to any other point on the card with proper timing. The arrival of a drive pulse having sufficient amplitude to switch the receiver can occur at varying time (known as clock skew), depending upon the load being driven by the OCD. By constructing an OCD such that appropriate power to drive into varying load capacitance can be programmed into it, clock skew is avoided and only a single OCD design is needed. The OCD is comprised of several circuit segments: a basic drive circuit designed to drive, e.g.