Ingemar,
Many thanks for the links. I strongly suspect that the technology to embed RF resistors in multilayer laminations already
exists, most probably within some of the Japanese companies.
The whole motivation for thinking of using such a structure is for high speed 1's and 0's data xmission down multilayer planar
mediums (PCB's!). Were not dealing with the same SNR's and signal amplitudes that the RF and Microwave folks are, but we are
embarking on trying to implement similar propagation mediums to the Microwave folk, only on quite a few more layers and at a
much lower cost threshold. That's what make engineering fun!
Best Regards
David Greig
______________________________
GigaDyne Ltd
http://www.gigadyne.co.uk
______________________________
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ingemar Hernefjord (KC/EMW)
Sent: 2005-June-13 07:24
To: [log in to unmask]
Subject: Re: [TN] Embedded Resistor materials for higher frequencies?
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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