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: PIN diode switch - how to change biasing Posted: Sat Sep 03, 2005 12:51 am
I am working on Switching circuits at 2-4GHz range using PIN diodes. I am designing the circuit in
ADS. Started with simple most series PIN diode switch, but facing some problem in that.
Problem : -
I used on series diode betweeen two microstrip lines terminated in Ports.
the diode has been
biased throguh high - low transmission lines. I gave bias voltage at P terminal of diode of around 2 Volts, the
diode is in forward bias. Even though I change voltage value to be -25 volts, the switch does not come in OFF
condition... i.e. S21 is still less than 1 dB.
Can some please help me out here.
can also write to email@example.com
Post subject: PIN DiodesPosted: Sat Sep
03, 2005 11:07 am
PIN diodes don't really turn on by voltage - they reach a low-impedance state by
(forward) current. So there has to be enough current flowing in the forward direction to give the proper
impedance. In the reverse (off) direction, the applied ("DC") bias must (significantly) exceed the peak voltage of
If you're sure you have those two necessary conditions, then there are only a couple of
1. Bad diode - PIN diodes can be damaged by both overcurrent and overvoltage.
around the diode - parallel microstrip lines might provide that if there's enough length where they're parallel
3. Impedances aren't what you think they are. (Not too likely, I know, but worth mentioning/checking)