ADC home pageIntroductionGoalsWhy digitize?Number RepresentationDigital to AnalogAnalog to DigitalApplicationsLiterature Citations

DAC Coding Schemes

Choose Subtopic

There are several ways around this problem.

a) Use binary-coded decimal MDACs. Instead of ladder networks designed for base 2, they use ladder networks designed for base 10. Brute force, but it works.

b) Use more binary bits than the minimum, and use a number that is sufficiently close to the scale factor desired that the error is insignificant.

For example, let's suppose we're using a 12 bit converter (quite common). Then for full scale,

Vout = (212/(212-1))*(212-1) * Vobserved = Vobserved.

But 212=4096, so 212/10 = 409.6 which rounds off to 410, and error of only 0.4/410 = 0.1%. 212/100 = 40.96 which rounds to 41, an error, similarly, of 0.1%. Good enough for most purposes.



DAC Ladder Networks DAC Coding Schemes DAC Speed and Glitches Scheeline Group Home Page Univ. of Illinois at Urbana-Champaign Home Page Department of Chemistry Home Page Creative Commons License System Homepage University of Illinois Homepage The Camille & Henry Dreyfus Foundation Homepage Home