A question about comparing ADC structures

[naalald]

Hi,
Can we compare different structures of ADCs through FOM (Figure Of Merit)?
You know, FOM is defined as:
FOM = P / (DR × BW)
In which DR = 2^b ( b is the Effective Number Of Bits), and BW is the Nyquist rate and P is the power consumption of the ADC.
With this definition, can we compare, for example, a pipeline ADC with a delta sigma ADC or a Flash ADC, and conclude that the one with a better FOM has a better design?
Any ideas?

 

[fanshuo]

yes you can
that is why it serve as scale to determine how good a ADC is

 

[pit1000]

I think, that at an estimation it is necessary to consider specificity of application. For different applications the concrete parametre is important, not FOM. How it is possible to compare through FOM 8b 1Gsps Flash and 24b 1Msps Sigma Delta? They are "animals of different kinds". FOM simply defines energetic cost of conversion and it is useful within concrete application if on critical parametres compared ADC coincide.

 

[spring1860]

i agree with pit1000

 

[naalald]

Hi,
Thanks all. That's right, pit1000. It's not fair to compare two ADCs with completely different applications. But, I think when we may use two ADCs alternatively, for example, with near resolution and output rates (signal bandwidths), FOM could be a useful way to decide on the better, since it expresses the energy per conversion of a ADC (the dimension is generally said in pJ/conversion). So, we may have, for example, a Delta Sigma ADCs with 14 bits and 20 MHz signal bandwidth with a better FOM, some day in future, and it replaces a pipeline architecture.