Parameters determining ADC dynamic range

[Vitamin-C]

Hi, All,

I have designed a ADC circuit which is tested and achieve the
SNR = 80dB.
Does it mean that it can also achieve a dynamic range of 10000:1 ??

I have tested with a sine-wave with a magnitude of 1/500 of full scale
and but the rms error is as high as 5% !!
So the dynamic range is even less than 500:1 ??
Is there other parameters I have overlooked?

Please help.
Vita

 

[Circuit_seller]

dynamic range adc

Hi

For ADCs Dynamic Range depeneds on INL(Integral Nonlinearity), SFDR(Spurious Free Dynamic Range). so you should measure this factors to say something about your ADC Dynamic Range.

Regards

 

[Vitamin-C]

dynamic range of adc

thank you for reply.

I have measured SFDR for different input magnitude
SFDR = 80dB for 0dB FS input
SFDR = 47dB for -33dB FS input


thx

 

[santhoshv78]

analog to digital converter dynamic range

SNR will also depend on the number of bits in ADC.
Max SNR you can acheive considering only quantization noise,for N bit ADC is given by 6.02N+1.76.
Your ADC should be more than 13-bit accuracy to get 80db SNR.
SNR degrades with lots of other noises in the system.

 

[nathan]

adc dynamic

Also, you need to specify at which input frequency ... SFDR change at different frequencies.

nathan

 

[santhoshv78]

dynamic range in adc

there is a relationship between the input frequency u give for the SNR testing and the sample frequency.
fin/fsample = (Number of cycles/ Number of record samples u take in the selected window)
I guess, this is to avoid the sample mismatch in the different cycles.
Anybody has more clear information.

 

[flatulent]

dynamic range

The quantization noise is spread across the frequency range from 0 to the sampling frequency. If you sample twice as much, the qunatization noise density is half. It is to your advantage to sample much higher than the Nyquist frequency. If you do not want to carry the high data rate further in the system, you can low pass filter using more bits than the ADC and then decimate.

There is also the problem with distortion from nonideal quantization levels. The Noise Power Ratio test from the decades old analog telephone industry is a better test of the converter.

 

[Vitamin-C]

measure adc dynamic range

hi, All,

thank you for all your reply.

Maybe the question changed as follows:

If, I have a ADC with SFDR of 80dB in the interest frequency band, what is the accuracy of measuring the energy of a sinewave with magnitude of
Vfullscale/500 ?

best,
Vita

 

[Regnum]

adc bits and dynamic range

error = 500 / (10^(80/20)) = 0.05 = 5%

 

[Vitamin-C]

adc dynamic range from bits

So, what 's the error in term of long term energy calculation for this small sine wave ?

 

[Vitamin-C]

different ranges adc

maybe I change the question,

If I see a datasheet with ADC dynamic range of 500:1 with < 0.2% error.
What does it mean in term of SNR and FSDR.

thanks
Vita