Hi Joel,
I am providing one reference input (inp B) to AD8302 from DDS (AD9834) at 10 MHz frequency and the other through DUT (input A). When I was checking the inputs at AD8302 through CRO, then input B which i got from DDS was showing perfect values (300mV Vpp, 10 MHz, o/p of DDS) while I wasn't getting a proper value at input A, which I m giving through DUT. My DUT's output showed 46mVpp, 8 MHZ, when not connected to AD8302 and 26 mV, when connected to AD8302.
One more thing: I checked the impedance of DUT through multimeter with reference to ground, it is in Mega Ohms, while AD8302 has internal impedance of 50 ohms. Do you think this is the main reason for AD8302 not getting the input from DUT? What impedance matching would you suggest if this is the case?
In summary, the DDS output (A9834) is reaching the input B of AD8302. So I understand the impedance of both (DDS o/p & 8302 i/p) matches. Whereas the other channel (input A) is receiving input from DUT, whose input stimulation is again derived from DDS only. Basically DDS output is split into two, one goes directly to AD8302 (inp B) , other is reaching channel A (input A) after passing through DUT as a stimulation signal. Do you think I will need to use some impedance matching while feeding o/p of DUT to 8302 since I'm not receiving DUT's signal at 8302's INPA.
Attached is the measurement scheme.
Sincere regards,
Dr.Babankumar