Current-steering FET logic circuit
US4939390A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 6, 1989 |
| Grant date | Jul 3, 1990 |
| Priority date | — |
| Expiry date | Jan 6, 2009 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K19/09436
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An integrated circuit, having applicability to GaAs circuitry, is disclosed for performing a current steering logic function. The integrated circuit comprises a switching circuit, a high impedance tail current source, and a pair of low impedances respectfully coupled to the tail current source through a respective one of the switching transistors. The resistors in the tail current source and in the load resistance are formed from sheet resistor material so that any process-induced variation in the resistivity of the sheet material causes a mutual but compensatory variation in both the load and current source resistors, maintaining a match between the current capability of the current source and the resistance of the loads. The follower circuit, on the other hand, comprises a low impedance FET and a follower current source having an active load whose current is primarily dependent on its threshold voltage. Accordingly, process factors which affect the threshold voltage of the low impedance FET also affect the threshold voltage of the active load in a mutually compensatory manner without adversely affecting the output levels of the logic level signals from the current steering circui…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.