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
page, please do.
Below are all of the forum threads, including all
the responses to the original posts.
Post subject: Negative Resistance Posted: Sun Sep 16, 2007
Joined: Fri Aug 11, 2006 6:07 am
I'm trying to synthesize a negative resistance to add to a circuit.
As far as I know there are three popular ways of doing so:
a device with negative resistance characteristics (e.g. Tunnel Diode).
2. Using a configuration of OpAmps with feedback that gives a negative
resistance when seen from the input.
3. Using a configuration of
BJTs, ot FETs.
It is the third method that I'm interested in
since I'm working at a somewhat high frequency and I need to be able
to integrate the resulting circuit on an IC. I'm specifically interested
in making a negative resistance using MOSFETs. I did read a couple of
papers that talked about the subject but it was quite general, with
no reference to biasing or methods of tuning. While I was able to sucessfully
simulate a negative resistance using two MOSFETs, the resulting resistance
was quite large (tens of Mega Ohms) and it was unstable when put in
a larger circuit.
The resistance I need is S-type, in the range
of tens of Ohms. Can anyone point me to where I can get more info on