folding ADC structure basic understanding

[jiaming_lee]

basic folding adc

Hi all:

I am now currently studying the folding ADC. I started from the simple example of 5bits, which has 2 bit coase and 3bit fine ADC. Please see two attached figures.

My questions are:
1. fold number should be alone with the coase bits; if 2 bit coase, 4 folder is required, right?

2. From the folding amplifier output waveform in the attached figure, there is 8 folder or 4 folder? or say, one cycle wave as 1 folder, or half of the cycle wave as 1 folder?

3. I am puzzled that inside -IR to IR output range, there should be 8 steps, because 3 bit fine ADC; so there are totally 8 sets of full range of -IR to IR apear at the output, but coase ADC can only distinguish 4 sets of range (2bits); how to correlate them?

I might understand the structure wrongly; welcome help me to clear some understandings on the issue.

thanks

jimmy

 

[jiaming_lee]

folding adc basics

sorry for not clear figures, here are the replacements:

 

[nooby]

understanding folding adc

Hi Jimmy,

1. 2 bit coase, folding factor is 4 for one folder
2. there are should be 8 folders for the this figure, and folding factor is 4, so 4*8=32 for the 5 fine bits
3. can't understand your question.

Hope it can help you.

Nooby