Continue to Site

Welcome to

Welcome to our site! is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

best measurement method ?

Not open for further replies.


Newbie level 6
Aug 8, 2010
Reaction score
Trophy points
Activity points
Hi all.

What would be the best measurement method for the following impedance measurement :-

I am injecting a signal of a few Hz (10Hz) up to a few MHz (3MHz) in increments of a few Hz. I then measure the injected signal and the returned signal which varies in amplitude depending on the frequency (device under test resembles a complex impedance with LRC components). This is performed in steps (1) first inject 10Hz - do measurements on both signals. Process the data then (2) increment signal .....

Time is not an issue.

I would ultimately like phase and magnitude (info) between the injected and returned signal.

I could use various ways of extracting this info but looking for advice from people more familiar with DSP techniques. (FFT, FIR only etc.....)

Thanks in advance

For low frequency problems as your application, the terms injected and returned signal should be better replaced by voltage and current in my opinion. You inject a current and measure voltage or vice versa.

You can refer to the design of state-of-the-art LCR meters, how they achieve a precise measurement. I think, the most simple and straightforward method is synchronous quadrature demodulation. FFT is a more general approach, although I don't exactly see an advantage for this application.

For the possible system topology, should also take a look at the Analog Devices AD5933, a signal chip DSP impedance analyzer. It uses FFT.

Thanks FvM points noted but because I have access to both input and output signals I would prefer the simpler way.

Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to