Programmable logic device macrocell with an exclusive feedback and exclusive external input lines for registered and combinatorial modes using a dedicated product term for control
US5300830A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 15, 1992 |
| Grant date | Apr 5, 1994 |
| Priority date | — |
| Expiry date | May 15, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K19/17716
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A programmable logic device (PLD) with an output macrocell circuit is disclosed. Specifically, there is a field programmable logic array (FPLA) using a dedicated product term for macrocell control. Particularly, the macrocells contain a faster, more flexible, and exclusive feedback line as well as an exclusive external-input line from an input/output (I/O) pad for a registered mode of operation. Moreover, there is a registered mode macrocell which has 1) a feedback path for the registered mode signals which is activated even when the I/O pad driver is disabled, 2) an input path, to the logic circuitry, over an I/O pad, 3) a feedback path for the registered mode signals while outputting the same registered mode signals, and 4) a feedback path which avoids the unnecessary signal noise emanating from the use of a 3-state device or output driver. In addition, the macrocell allows for a disabled tri-state and still have the feedback intact for the combinatorial mode; thus, avoiding the extra noise that a tri-state creates.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.