Partial isolation of power rails for output buffer circuits
US5204554A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 6, 1991 |
| Grant date | Apr 20, 1993 |
| Priority date | — |
| Expiry date | Dec 6, 2011 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L2924/3011
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An output buffer circuit (10) delivers output signals of high and low potential levels at an output (V.sub.OUT) in response to data signals at an input (V.sub.IN). The output buffer circuit comprises an input stage (12) coupled between a relatively quiet power supply rail (V.sub.CCQ) and a relatively quiet power ground rail (GNDQ), and an output stage (14) coupled between a relatively noisy power supply rail (V.sub.CCN) and a relatively noisy power ground rail (GNDN). A first coupling resistor (R5) is coupled between the relatively quiet and noisy supply rails (V.sub.CCQ, V.sub.CCN) for reducing V.sub.CC droop in the relatively noisy supply rail (V.sub.CCN) which in turn reduces output step in voltage during transition from low to high potential level (LH) at the output (V.sub.OUT). A second coupling resistor (R5A) is coupled between the relatively quiet and noisy ground rails (GNDQ,GNDN). The coupling resistors (R5 and R5A) have low resistance values selected for partially coupling the supply and ground rails respectively, while maintaining partial isolation for protecting input dynamic threshold levels of quiet outputs. The first coupling resistor (R5) is coupled between supply r…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.