Hi all, was hoping to get some clarification on real-world ADC bit
toggle values on the 8bit-1Gsample iADC.
Looking at the Atmel/e2v AT84AD001B data sheet, we found the "full scale
differential input voltage" was 500mVpp, impedance 50 ohm, so using
R=50ohm, V=500mV/(2^8-1), P = V^2/R:
Pdbm = 10 log10(V^2/R) + 30 = -41dBm
i.e. -41dBm will tickle the first bit. We thought there might be a
factor of two from the minicircuits balun changing the signal from
single ended to differential (500mV -> 250mV), which gives -47dBm.
This is about 20dBm lower than I found in the mailing list, where I
found a quote stating -27dBm is close to 1 bit sampling. Can anyone
explain the finer details I've missed? How is the S/H amplifier part of
the AT84 configured?
Cheers
Danny
