Delay circuit for a monolithic integrated circuit and method for adjusting delay of same
US4894791A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 10, 1986 |
| Grant date | Jan 16, 1990 |
| Priority date | — |
| Expiry date | Feb 10, 2006 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K19/00323
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A delay circuit that can be implemented in a monolithic integrated circuit includes a plurality of capacitor/laser-fusible link series pairs. Delay of a binary output signal of the circuit with respect to an input transition is directly proportional to the amount of capacitance connected into the circuit. Because the laser-fusible links can selectively be opened with a laser, the amount of capacitance connected into the circuit can incrementally be reduced; thus, the delay of the circuit is reducibly adjustable to a desired value. By including a plurality of conductive element/laser-fusible link series pairs in the delay circuit, the delay of the circuit is also increasingly adjustable. A method for economically adjusting the delay of each of many like delay circuits embodied in a semiconductor wafer includes measuring a sample of the delays of the delay circuits, calculating an average delay, determining the difference between a desired delay and the average delay to determine an incremental amount of delay to eliminate or to add, determining from predetermined data which fusible links should be opened, and using a laser beam to open the appropriate links.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.