Hi Miguel!,
Thanks for your useful reply.
Please find point-wise reply as given below:
1- unless you know your impedance range, you wont be able to design a robust system... ie. it is not the same to excite a 5pF cap than 1uF cap.
A: I will try to provide you data that are measured using LCR meter and Impedance Analyser. But, probably, its available up till 1MHz sweep. It includes resistance, capacitance, impedance, phase angle, dissipation factor etc. The data covers the whole sampling range. It is measured using the samples that covers full range. That will help you get an idea about impedance range.
2- As you pointed, it is preferred a clean signal... the problem, in your case is the wide excitation signal range.
You can built a simple LPF... but not sure if will significantly improve the performance as the AD8302 BW is 30MHz... unless you build a variable LPF...
A: In my case, while characterizing network response, sweep range will be 100 KHz to 30 MHz. So you can advise if it serves the purpose for LPF selection.
3- You didn't answer the question... but based on your answer I guess you already evaluate AD8302 performance and it is good enough for you.
A: Yeah, I think so. It seems it can work for the DDS applications of the type requiring network response measurements (magnitude and phase) comparing reference signal with response signal in phase and magnitude, as discussed in the pdf article on "DDS Applications" of Analog Devices.
4- Unless you are using a dual sampling ADC, you will add some error in the measurements... as you dont know if during sampling one of the output, the load has changed of impedance..
A- It's ok, I can use dual sampling ADC if you suggest so. I was thinking to use PC based data acquisition card initially, as I'm possessing such a card readily. It has multiple analog/digital i/o channels that it can read/write. I'm not sure whether its dual sampling type? and at what rate? I will check details and update you model tomorrow.
Thanks and sincere regards,
Dr.Babankumar