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AD797 as splitter buffer

Question asked by rianovich96 on Apr 13, 2011
Latest reply on Apr 14, 2011 by Georgy

Hello friends,


I want to buffer/split a very clear 10 MHz sine wave signal from a source into four ways. Searching for a high quality oa, appears AD797 to be my sollution but I need a second opinion and few design tips. Source has following specifications which of course, needs to be conserved as much as possible (noise, spurs):


• Z=50 Ohms, 0.5Vrms


• Phase Noise (SSB): 1 Hz <-75 dBc/Hz
10 Hz <-89 dBc/Hz
100 Hz <-128 dBc/Hz
1000 Hz <-140 dBc/Hz
10 kHz <-147 dBc/Hz


• Spurs:
Harmonic: 2nd <-60 dBc
Other: <-65 dBc
Non-Harmonic: 1 Hz to 1 kHz <-89 dBc
1 kHz to 10 kHz <-97 dBc
10 kHz to 100 kHz <-100 dBc
>100 kHz to 1 GHz <-68 dBc


I plan to parallel 4 oa, non-inverting, on the same 50ohm input termination resistor. Minimum 26ohm feedback, like fig.50 of datasheet. The goal is minimum noise but also keeping harmonic spurs <-45dbC. Comments appreciated.