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Time Domain Question

Question asked by mikejvir- on Jan 3, 2016
Latest reply on Jan 14, 2016 by mikejvir-

I am a little rusty in my time domain analysis so I am posting here hoping to find a answer.  My problem started with attempting to compare two different manufacturers of SMA connectors (call them Connector E and Connector L).   I have a E5071C that goes to 20 GHz and has option 010.  The calibration was done using an 85052D between ports 1 and 2 with an IF bandwidth of 1 kHz and frequencies from 1 MHz to 20 GHz with 20000 points.

Gating was done from -0.25 to +0.25 ns using a bandpass response.  Page 1 of the attachment show a reasonable agreement  but Connector L has a high frequency resonance at 17 GHz.

Strangely, this is not what bothers me.  If you look at the Low Pass Impulse (page 2) and Low Pass Step Response (page 3) you can see that the Connector L board has a high ripple content along the transmission line between the connectors.   The transmission line is about 2.5 inches long.  Both boards where manufactured at the same time and are made of Rogers 4003 material.  This is real because I first saw it on a smaller length of transmission line (about 1.2 inches) and was not absolutely positive they were manufactured at the same time.

From my rusty knowledge of the time domain, I would not expect the connectors to affect the response in the transmission line area.   Where am I going wrong?

Thanks for the help in advance.

Michael J. Virostko
Integrated Device Technology, Inc.
515 Groton Road, Suite 102, Westford, MA 01886