how to assign the ADC dynamic range for receiver design

[foxgan]

adc dynamic range

Hi ALL
Now I'm designing a superheterodyne receiver. Now I have some puzzles:
1 How to partition the dynamic range of 16-bit ADC? The AGC should guarantee the signals from demodulator for which part of the ADC dynamic range
2 When I calculate the level of the demodulated signal, there are four signal I-/I+ and Q-/Q+, how to calculator the rms level of the demodulated signal

 

[vfone]

adc parameters and receiver sensitivity

To define the portion of the Dynamic Range of ADC where AGC is active you have to do an RF System analysis which has to include Interfere Levels (Blocking, Adjacent Channel, etc) and Fading Margin. All these parameters are dependent by the Specifications of the Network where your receiver is used.

To calculate Vrms of IQ signal you can measure the peak voltage of each (for e.g. I+ to ground, and Q+ to ground) and:
Vrms = Vpeak * 0.707

 

[dinone]

agc dynamic range calculation

Depend also of some parameters as sensitivity, overall gain, phase noise. You have to attenction also the ADC type (pipeline or Sigma delta), how mani bits you want to use, sampling frequency and jitter. The ADC is the intermediate point from analog to digital worlds, so it is not so simple to analyze its dinamic range.

By

 

[OMEsystem]

adc dynamic range definition

To define the portion of the Dynamic Range of ADC where AGC is active you have to do an RF System analysis which has to include Interfere Levels (Blocking, Adjacent Channel, etc) and Fading Margin. All these parameters are dependent by the Specifications of the Network where your receiver is used.

To calculate Vrms of IQ signal you can measure the peak voltage of each (for e.g. I+ to ground, and Q+ to ground) and:
Vrms = Vpeak * 0.707

It's my first time to hear fading margin? What's it? Does it overcome the amplitude
variation due to fading?
What's the practical value of fading margin?
Thanks,

 

[foxgan]

receiver dynamic range calculation

Ok，thanks . the design is so complex that where i can get a book or article which particularly declares on the design?
thanks!

 

[Mazz]

adc snr fading margin

Quizeng Gu
RF system design of tranceivers for wireless communications
Springer

Good text for RF system design; page 284 deals with this issue

 

[viswa]

adc receiver design

see if the file attached can be useful for u. it explains graphically hw to find the dynamic range of an ADC.

 

[vfone]

specification of adc dynamic range

Fade margin definition:
https://en.wikipedia.org/wiki/Fade_margin

 

[OMEsystem]

quizheng gu

Fade margin definition:
h**p://en.wikipedia.org/wiki/Fade_margin

By the definition of this website, it looks like we need to do an overdesign of
SNR to overcome the fading loss. I make a more detailed statement as following,
please help me check I am right or wrong.

Assume the SNR requirement of Baseband is 21dB to do the demodulation.
We need to design the SNR more than 21dB by fading margin(assume 6dB).
So the Signal to Noise level at input of ADC should be more than 27dB, right?

 

[vfone]

receiver dynamic range, wiki

Everything is related to the Network specification requirements where the receiver is used. Usually these specs doesn’t specify fading performance at the limits of the receive dynamic range, but if they specify you have to increase the limits of SNR.

 

[foxgan]

dynamic range adc

I can't open the website about fading margin.