Level Control Loop with AD8314 RF Log Detector

Question

I am designing an RF level controller with the AD8314 Logarithmic RF Detector, using it's non-inverted output (V_UP, pin 6). 
 According to the datasheet, the loop filtering capacitor Cf should be placed between pin 4 (FLTR) and pin 6 (V_UP). 
 Maybe I'm wrong, but if pin 4 (FLTR) is an internal current summing node, why not connect Cf directly between pin 4 (FLTR) and ground like with the AD8315? 
 Thank you very much in advance, and best regards. 
 Alberto

enash · Accepted Answer

The devices have different internal structures. So the AD8314 recommendation for the connection of the filter cap is correct.)

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Level Control Loop with AD8314 RF Log Detector