We are designing DDC receiver (decided to use AD9461) .
We must provide sensitivity above -120dBm (10 dB SNR / bandwidth 12kHz). To simplify the calculations I take unmodulated carrier.
My preliminary calculations are:
AD9461 SNR = 77 dBFS
After digital down conversion:
SNR Improvement (dB) = 10 x log (Sampling Rate/2x Signal Bandwidth)
SNR Improvement (dB) = 10 x log (122.880e6 / 2x 12e3) = 37dB
SNR summary = AD9461 SNR + SNR Improvement= 77 + 37 = 114dB
But for sensitivity -120dBm we must have SNR= 120dB + 10dB= 130dB
1) Tell me please, my calculates is correct?
2) If I can't provide the sensitivity -120dBm on AD9461, what can I do in this case?