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| Date: | Mon, 13 Jun 2005 08:24:28 +0200 |
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David,
we don't use embedded R at GHz bands. Instead we use various metal oxide versions, as most do. Many a times the RF requirement is 1% tolerance and 10-50 ppm/K on that, which seems to be an impossible equation with ordinary embedded resistors. However, it seems to me, as there has been a lot of experimenting. E.g. the below from MOTA. These polymer inc based resistors are said to be useful at 3 GHz. By means of a silver matrix between the resistor and the copper line, MOTA claim they have obtained stability. Some more US companies have tried, but not many publish their findings. One design guy here had a comment to embedded R :" Gosh! Man, are you crazy. With embedded resistors I can't do fast changes of values. "
Well, well, that might be a argument too...RF is still about magic...
http://www.smta.org/files/SMTAI02-Croswell.pdf
Ingemar Hernefjord
Ericsson Microwave Systems
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of David Greig
Sent: den 11 juni 2005 18:49
To: [log in to unmask]
Subject: [TN] Embedded Resistor materials for higher frequencies?
Hi TN,
Is there such a thing as an embedded resistor material that's suitable for higher frequencies? Application does not warrant
great precision (~5% to 10%), it's just for dealing with signal attenuation at stubs.
Could be part of a Cu foil, or deposited and cured/baked. Might be inner or outer layer. Have considered carbon contact type
materials but do not have much faith in long term reliability (for class 3 Telcom).
All of the embedded materials that I've come across are nickel based, which is not going to be a realistic proposition due to
the ferromagnetic properties.
Best Regards
David Greig
______________________________
GigaDyne Ltd
http://www.gigadyne.co.uk <http://www.gigadyne.co.uk/> <http://www.gigadyne.co.uk/>
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