AnsweredAssumed Answered

AD9913 Evaluation Board

Question asked by Er1cPhoton on Apr 3, 2015
Latest reply on Apr 10, 2015 by Er1cPhoton


This is my first-time post in engineer zone and hope to get some help here.


We are using AD9913 in one of our projects. We bought the AD9913 evaluation board and we followed their design of the output stage on our PCB. (See the picture below).


      Figure 1 Evaluation Board Schematic from Analog Device INC.

We followed every other thing, the two 50ohm resistors R156 and R157 to ground, the transformer, and the 100MHz LPF followed by the Amplification stage designed by ourselves. The specific component that caused trouble is the R155. According to the BOM (Bill of Materials) provided by Analog Device INC. It is a 0 ohm resistor. (See the Picture below)


Figure 2 BOM file from Analog Device INC.

However, as we put the R155 on our PCB the signal was gone. The strange thing is in the BOM file they marked R155 as red and also crossed it out. It seems they did not use this component. But, the R155 is actually on their evaluation board and we could get a clear signal on the evaluation board.

So My question is: Is R155 resistor necessary? What does it do?  Is the R155 on the evaluation board really 0ohm?