[SOLVED] what is meaning dynamic range of an ADC?

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v_naren

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What does a data sheet mean when it says the dynamic range of an ADC is 80dB?
Can some please explain or give directions to some good documentation which explains the concept of dynamic range of an ADC.

Thank you
 

Yes , you can check the google

The dynamic rang of ADC mean the maximum and minimum input range
 

for ADC:

DR is the ratio of input signal for which max SNR is achieved to input signal for which SNR=1.

You can read e.g. in Razavi's RF Microelectronics about it.
 

for ADC the dymanic range is another form of resoltion.
 

what i inferred is DR can be used to compare two systems.high DR better system
it gives maximum voltage signal that can be given to system.

The system dynamic range should be higher than signal-to-noise ratio of the input signal (SNR according to the maximal signal).
If system dynamic range is lower, the acquired data are distorted by the acquisition system.
 

Gennerally, in the theory , the SNR:

SNR=6.02N+1.76+20log(k) (I)

K: the oversampling rate(OSR)=(ks/2)/Kin,

But actually , the measure do not meet the value.

such as a 14bit ADC (Nyquist sample):

in theory the SNR(Therory)=6.02*14+1.76

but the measure SNR(measure)<SNR(Theory)

Ex. a Nbit ADC input signal Vpsin(ωt),the reference is Vref+, Vref-,

RMS(the maxim input signal)=Vref+-LSB-Vref-
RMS(the noise power)=LSB/(√12)
LSB=(Vref+-Vref-)/(2....2)
--------
N


the DR=20log(the maxim range signal power)/(the noise power))
=6.02N

in theory , DR=6.02N
 

Generally the Dynamic Range (DR) of an ADC is defined for a sinusoidal input signal, i.e. Asin(ωt) where the amplitude A is chosen such that the ADC is operating at fully scale (FS) and ω=ω_s/2. ω_s/2 is the minimum allowed sampling rate, which is also known as Nyquist-sampling rate. If the quantization
process of the ADC can be modelled as additive white noise, the output of the
ADC has a dirac-component as ω with an amplitude of A=FS/2 and white noise spectrum with a power spectral denisty of 1/(12f_s) where fs=ω_s/(2pi).
In practical ADCs the noise floor is generally determined by thermal noise rather than by the quantization noise of the ADC which is typically higher than the quantization noise floor.
In order to give you a more precise answer regarding your ADC with 80dB DR it is important to know how it is measured, i.e. the input signal must be known and also the sampling rate of the ADC.
I hope my comments are helpful for your basic understanding of noise in ADC.
BR
 

May be the following article will help:

IEEE Standard for Terminology and Test Methods for ADC
 

in audio apllication, the DR is measured the output noise floor when the input is -60db, then add -60db to get DR.
 

HERE i WANT TO INSISITS IF WE INCREASE OUR NUMBER OF BIT(N)
OUR DYNAMIC RANGE WILL INCREASE BY 6dB

the DR=20log(the maxim range signal power)/(the noise power))
=6.02N
in theory , DR=6.02N
 

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