ADC ENOB and SINAD of LTC2500 and AD4030

Hi,

Effective and Peak-to-Peak resolution should not be confused with ENOB, as ENOB uses an FFT analysis of a sine-wave input to the ADC while Effective resolution and Peak-to-Peak resolution measure the ADC's noise performance at essentially narrowband/DC measurement where spectral distortion is not factored. The peak-to-peak resolution represents the resolution for which there is no code flicker or noise-free code and so it gives a better indication of the performance vs effective resolution. Just like how the dynamic range is calculated, the effective resolution is calculated using the rms noise, whereas the peak-to-peak resolution is calculated based on peak-to-peak noise. The peak noise is statistically 6.6 x rms noise; therefore, the effective resolution is greater than the peak-to-peak resolution by 2.7 bits but does not highlight the number of bits that flicker. May we know your specific application so we can assess which ADC is more suitable for it?

Thanks,
Andrei

It is not clear to me what you are trying to point out from your text above. Do you have any available references? 

(I found this one https://www.analog.com/media/en/technical-documentation/application-notes/AN-615.pdf  but this does not really means that performance is going to be better)

Regarding this, "FFT analysis of a sine-wave input to the ADC while Effective resolution and Peak-to-Peak resolution measure the ADC's noise performance at essentially narrowband/DC measurement where spectral distortion is not factored", yes my signal is going to be of an oscillatory nature....that's why I am examining the ENOB and I see that performance is much lower than this advertised.

My application requires a precision ADC for a single ended signal (0...5V), for a bandwidth of 50kHz and being able to distinguish a voltage level of 100-400 nV minimum.

The ADC has to be a SAR and we are planning on oversampling && decimating to achieve a sampling frequency of 1.6MSample/sec to get 2 additional bits, since the ENOB is relatively very low for both the LCT2500 and the AD4030.

It is not clear to me what you are trying to point out from your text above. Do you have any available references? 

(I found this one https://www.analog.com/media/en/technical-documentation/application-notes/AN-615.pdf  but this does not really means that performance is going to be better)

Regarding this, "FFT analysis of a sine-wave input to the ADC while Effective resolution and Peak-to-Peak resolution measure the ADC's noise performance at essentially narrowband/DC measurement where spectral distortion is not factored", yes my signal is going to be of an oscillatory nature....that's why I am examining the ENOB and I see that performance is much lower than this advertised.

My application requires a precision ADC for a single ended signal (0...5V), for a bandwidth of 50kHz and being able to distinguish a voltage level of 100-400 nV minimum.

The ADC has to be a SAR and we are planning on oversampling && decimating to achieve a sampling frequency of 1.6MSample/sec to get 2 additional bits, since the ENOB is relatively very low for both the LCT2500 and the AD4030.

The AD4030 has lower noise and better linearity than the LTC2500-32. The number of bits is not an indicator of accuracy. Better indicators of accuracy are INL for DC applications and THD for AC applications. Transition noise is a good indicator of DC noise performance and SNR is a good indicator of AC noise performance. The LTC2500-32 provides 32 bits of resolution to minimize roundoff error when averaging large numbers of samples. If you look at the AD4030-24 data sheet you will see that when doing block averages, the data format is 30 bits for this same reason.