[sdiy] (oops) EN #76 question

[Neil Johnson]

Tim Ressel wrote:
> I am looking at Electronotes #76 figures 8a and 8b. 8a shows an 8-bit dac made from discrete binary-weighted resistors. We've all seen this type of dac.
>
> Figure
>   8b shows a dac that has gaussian distribution. The thing is, this
> circuit will only produce 8 different levels, as opposed to the 256
> levels of the 8a circuit. Am I missing something here?

Its the usual trick for generating a sine wave with pseudo better than 8 
bits resolution, by sacrificing other waveforms.  You feed in a bit 
pattern that turns on multiple 'bits', which then sum to give each 
sample of the sine wave.  So what you're seeing is not a Gaussian 
distribution but a sine wave.

Neil
-- 
Modules and more :: www.cesyg.com
Homepage :: www.njohnson.co.uk ::