Digital-to-analog converter with segmented resistor string
US5495245A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 26, 1994 |
| Grant date | Feb 27, 1996 |
| Priority date | — |
| Expiry date | Apr 26, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03M1/765
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
The number of resistors and switches required for a voltage-scaling digital-to-analog converter (DAC) is greatly reduced by segmenting the voltage decrementing resistor string into two separate outer strings and an inner string. The outer strings decrement a full-scale voltage in accordance with the most significant bits (MSBs) of the input digital signal, while the inner string decrements the least significant bits (LSBs); alternately, the outer strings can decrement the LSBs and the inner string the MSBs. Opposite ends of the inner string are connected to corresponding points on the two outer strings through passive switched taps on the outer strings that allow the DAC to function as a potentiometer or rheostat, and "slide" up and down along the two outer strings as the input digital signal varies. An analog output is tapped from a selected point on the inner string whose voltage elevation is controlled by the switching of the outer strings. The outer strings are preferably switched in a sequence that adds a transient finite resistance to the circuit during switching, but avoids large scale glitches due to open circuits or short circuiting part of the string.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.