Impedance matching when AD9717 or AD9779A interfaced with ADL5375

Question

Accepted Answer

Question Can you confirm why I need to use 500ohm or 50ohm impedance matching for the 
 AD9717 and AD9779A interfaced to ADL5375.
 Sorry for that basic questions, but I am from the digital world.

Answer Remember, that the AD9717's and AD9779A's output and ADL5375's input 
 common-mode bias levels are both 500mV and hence do not require voltage 
 shifting circuitry. 
 
 With regards to the AD9717, whose fullscale output current=2mA, then to obtain 
 500mV bias on the output the voltage can vary from 0 to 1V for single-ended. 
 Therefore, the corresponding resistance (RBIP, RBIN) = 1V/2mA = 500ohms.
 
 In the case of the AD9779A, the fullscale output current=20mA and to have an 
 output single-end voltage from 0 to 1V, then the corresponding resistance 
 (RBIP, RBIN) = 1V/20mA = 50ohms.
 
 Refer to Figure 59 in the ADL5375's RevB datasheet for further details

Popular Forums

Product Forums

Application Forums

Design Center Forums

Highlighted Webinar

Places

Libraries

Upcoming Learning & Events

Challenge Yourself!

What's Brewing

Places

Resources

Visit ContentZone

The Latest Read

New Release

Recent Technical Insights

Products Mentioned

AD9779A: FAQ

Before You Switch