[SI-LIST] Re: I need to compensate for component with too high an input capacitance.
- From: Bob Ross <bob@xxxxxxxxxxxxx>
- To: brimdavis@xxxxxxx
- Date: Wed, 22 Mar 2006 14:49:21 -0800
Brian provided a reference to T-coil peaking. This is an old
Tektronix technology kept as a trade secret since the 1960's
While mentioned in some trade publication articles, several
books in the 1990's, including the one Brian referenced, discuss
T-coils. I had the privilage or working with Chapter 10 author,
Carl Battjes, on the original lossy T-coil formulation (without
Rcomp) mentioned in the Hagerman paper.
A new book is available from Springer by two Slovenian authors,
Peter Staric and Erik Margan, on "Wideband Amplifiers" cover some
of the T-coil technology and extensions:
http://www.springer.com/sgw/cda/frontpage/0,11855,4-102-22-70230149-0,00.html?changeHeader=true
A full color 84 page excerpt is available on this link, and
full color color CD comes with the book.
Another research reference showing a recent T-coil application
for ESD circuits is:
http://www.ee.ucla.edu/~razavi/papers/Journals/G&RDec03_1.pdf
Bob
brimdavis@xxxxxxx wrote:
> ( re-posting, apologies if any duplicates show up )
> Tom wrote:
>
>>They now claim that it is around 6 pF instead of 2 pF. This, they
>>claim, is why driver with an 80 ps rising edge causes
>>such "excessive ringing" on the input.
>>
>
>
> If the problem is ISI from the {re}reflections off the big
> input C, one simple fix is to stick a differential pad in front
> of the reflective load - see further notes below.
>
>
>>How best to do this? I have done some spice analysis on a circuit
>>that is known as the "constant resistance termination".
>>
>
> For another discrete-laden matching approach that can improve
> rise time for a big C, google "T-coil peaking".
>
> http://www.hagtech.com/pdf/tcoil.pdf
>
> Chapter 10, The Art and Science of Analog Circuit Design,
> Williams (ed.), 1995 ( chapter on T-coils )
>
> I've done simple inductive matching for narrrowband clock inputs,
> but have never been brave enough to try a fancier peaking scheme
> for, say, a 64 bit wide differential bus.
>
>
--
Bob Ross
Teraspeed Consulting Group LLC Teraspeed Labs
121 North River Drive 13610 SW Harness Lane
Narragansett, RI 02882 Beaverton, OR 97008
401-284-1827 503-430-1065
http://www.teraspeed.com 503-246-8048 Direct
bob@xxxxxxxxxxxxx
Teraspeed is a registered service mark of Teraspeed Consulting Group LLC
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