[sdiy] Expo converters, lin log etc.

[Eric Brombaugh]

Antti Huovilainen wrote:
> On Thu, 1 Feb 2007, Eric Brombaugh wrote:
> 
>> I've got no experience with delta-sigma ADCs, but the delta-sigma DACs 
>> I've used are perfectly capable of generating DC. The big problem 
>> you'll have with them is that they're typically designed for audio 
>> output levels (~2V p-p), so in order to take advantage of 24-bit 
>> resolution you need CV processing circuits that are accurate to 0.1 
>> microvolts (2V /
> 
> And if you check the noise levels, you'll see that most have around 
> 100dB SNR which is roughly equivalent to 17 bits.
> 
> Another problem is that the DC offset is not very accurate since it's 
> irrelevant for audio use.

Good points. I have noted that some DACs provide an output pin for their 
internal midpoint DC reference node so you could theoretically subtract 
it out externally. I wonder how accurate that would be.

Eric