Hi there, I am using an Analogue Signal Generator EXG 5171B from Keysight for my measurements. I simply need to supply the analog (Sinewave) to my DUT (Schottky diode) using this instrument to evaluate the rectification ability of my diodes at various frequencies and amplitude and determine the cut-off frequency of my Schottky diode.
Since my DUT impedance is not 50 ohm, the signal generator is not sending the same voltage (amplitude) that I set in the signal generator, I know this is due to the fact that the instrument output impedance by default is 50 ohm and it has to be changed to high Z which can ensure the same voltage (what I set in the ASG) goes to my DUT.
I don't know how to set this in my particular Signal Generator, if anyone knows, please help me to set this up?
Your valuable suggestions are much appreciated!
Kalai.
Hi Kalaivanan Loganathan ,
I guess high Z would aggravate your problem, Z = 0 would be a solution, but this doesn't seem to be available.
A possible solution is outlined on page 116 of the user's manual: You could tap the voltage at your DUT, and route it to the ALC input. Probably, you'll need an amplifier with high input impedance and the possibility to adjust gain and offset.
Oops, I just saw that an "ALC input" seems to be a feature of the models N5173B and N5183B only. Perhaps one of these is available in your lab?
Perhaps you can just use 50 ohm termination (just a resistor or coax termination/ 20 dB attenuator (high value attenuators provide nearly perfect termination).
Dear Kalaivanan Loganathan
welocme,
Adding to the colleagues above. You can use a wide bandwidth unity gain amplifier to buffer your source.
This is one solution.
The other solution is to add 50 ohm resistance in series with the diode or any suitable current limiting resistance in series with the diode. In this case you can use the series resistance as a current measuring resistance in the diode.
Best wishes
Abdelhalim abdelnaby Zekry Yes, I totally agreed. Thanks for the clarifications and yes I am moving towards option 1 that you mentioned (having an amplifier prior to my DUT), The option 2 that you suggest is something that I would like to try as well.
Dear @ Kalaivanan,
In commenting the answer of Joerg Fricke , you wrote: I am thinking either have an amplifier prior to the DUT or have 50 ohm series resistance in series with the diode – 📷Kalaivanan Loganathan
This is really my answer which introduced the solution.
Is that write?
Best wishes
Abdelhalim abdelnaby Zekry Yes, you're right, I wrote you as well and I don't know why it is not appearing below your answer, sorry for that! and thanks for the clarifications.
My dear Kalaivanan Loganathan
My colleague Joerg Fricke is very known to me and he is a very respected colleague. I am very sorry to bother you. But one advise: You do not need to select a best answer. It is just elective and when few answers are collaborating to give a complete answer so one can not clearly choose a best answer.
Best wishes and wish you success and the colleagues many blessings.
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