Digitally compensated multiplying digital to analog converter
US4779029A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 11, 1985 |
| Grant date | Oct 18, 1988 |
| Priority date | — |
| Expiry date | Mar 11, 2005 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03M1/785
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A multiplying digital to analog converter using ladder networks and binary weighted load compensation to allow integration and video frequency operation. In one form, the circuit is configured from field effect transistors which incorporate by virtue of their structural and operational characteristics both the switching and resistive functions of R-2R ladder networks. The circuit is used to convert digital format words representing intensity and color (red, green and blue) into analog red, green and blue display drive signals. According to that configuration, the output of the digital to analog intensity word converter serves as the reference for the three digital to analog color word converters. Loading effects attributable to differences in the bit content of the color words are offset by a binary weighted switched load which is responsive to a digital compensation word. The switched load is also connected to the output of the intensity word converter. This circuit configuration provides an implementation by which the color (hue and saturation) in analog form can be held constant while the intensity of the color is selectively varied.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.