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AD9956 CML DRIVER ISSUES

Question asked by ALLR on Feb 28, 2012
Latest reply on Feb 28, 2012 by DSB

I'm working in a project, also with the AD9956, and I have the following doubts regarding the CML driver:

 

1: Did the AD9956 CML driver have integrated pullup collector resistors?

 

2: What´s the value in Ohms?.

 

3: In the datasheet, Analog specified that the Common-Mode Output Voltage is equal to 1,75 V. Under what conditions was calculated this parameter?.

 

4: Why is it used a 360 Ohm Voltage divisor at the CML driver output in the AD9956 Eval Board ? In my opinion is the Vcc= AVDD_CP/2 for collector resistors (if there is an integrated collector resistor), but it´s not clear in the documentation. Figure 1.

 

5: In the AD9956 Eval Board the differential impedance after DC block capacitor is 100 Ohm (two 50 Ohm resistors), why this specific value? Figure 1.

 

Sin título.png

 

Figure 1.

 

Thanks in advance to ENGINEERZONE.

 

Lacy McLaury

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