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IMS resistors with partial wraparound - RF Cafe Forums

Because of the high maintenance needed to monitor and filter spammers from the RF Cafe Forums, I decided that it would be best to just archive the pages to make all the good information posted in the past available for review. It is unfortunate that the scumbags of the world ruin an otherwise useful venue for people wanting to exchanged useful ideas and views. It seems that the more formal social media like Facebook pretty much dominate this kind of venue anymore anyway, so if you would like to post something on RF Cafe's Facebook page, please do.

Below are all of the forum threads, including all the responses to the original posts.


Peter
Post subject: IMS resistors with partial wraparound
Unread postPosted: Wed Jun 29, 2005 4:12 pm

I am reading about IMS resistors, that are said to be more suited for microwave performances than standard SMT resistors.

Does anybody know if it is stricly a question of wraparound?

For example I saw simulations with manufacturer's model on ADS comparing kemet resistors and IMS. For 0805 package between 1 and 2 GHz there was a significant slope 1dB on the attenuation. For the IMS resitors however this slope was minimal.

I am suprised that just this wraparound question would cause such a difference.

Anybody experienced the same? Any comments?


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Guest
Post subject:
Unread postPosted: Tue Jul 05, 2005 1:08 pm

Wraparound certainly is a big part of it. A lot depends on the value of the resistor and the intended use. For large value resistors, the wraparound can add a signficant parallel capacitance term. For low value resistors, the wraparound can add a significant series inductive term. The method of attachment can also be a significant factor.

For example, about 20 years ago I designed a transimpedance amplifier that used a descrete resistor to set the transimpedance gain (for a fiber optic receiver application). I use a non-wraparound resistor (from IMS and others) because the sub-pF capacitance from the wraparound termination would dramatically affect the bandwidth (due to the multiplication from the amp).


Posted  11/12/2012
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