how to design PIN diode driver - high voltage and high speed

"Phil Hobbs" <pcdhSpamMeSenseless@pergamos.net> wrote in message 
news:QdydnVSgMPimBw3VnZ2dnUVZ_jidnZ2d@supernews.com...
> The guys down the hall were building a 100-GHz acoustic microscope that had 
> to work in superfluid helium.  I don't think they ever got it working.

Hmm... perhaps they're working on the 100mpg car X prize by now. :-)

100GHz in the early '80s... definitely pure research, I would think (e.g., you 
work your best at it, but you don't really expect you'll be able to make it 
work...).

>
> Yes, I would certainly agree that proper filtering to separate thePIN
> bias from the RF is a good idea. =A0The faster you need to switch, the
> more critical that becomes. =A0It should be an advantage to consider not
> only a low-pass filter for the bias but a high pass filter for the RF--
> or other methods to reduce the capacitance that thePINswitch must
> drive. =A0Of course, be careful about the return path for the current
> that charges the capacitance especially on the receiver side, so that
> you do not expose the receiver input to excessive current. =A0A power
> mosfet that switches several hundred volts in a few tens of
> nanoseconds will be generating quite a bit of available energy to a 50
> ohm 3-30MHz input! =A0If there exists between the fastPINdriver
> circuit and thePINdiodes a low pass filter, and also between thePIN
> switches and the receiver input (or transmitter output) a high pass
> filter, and the filter passbands do not overlap, then there should be
> decent isolation to protect the receiver input. =A0I can tell you that I
> also usePINdiodeclamps on the input to a receiver I recently put
> into production, and they are able to absorb transient energy quite
> nicely. =A0They are just diodes normally reverse-biased by several
> volts. =A0In a switched system, I would consider driving them actively,
> using differential drive so that there is no (or very low) transient
> on the RF input that they shunt to ground when they are "on." =A0If the
> diodes are matched (as they are in a packaged pair, such as Avago
> HSMP-3822) and you drive them to the "off" state symmetrically, they
> should inject very low pulse energy into the line they are switching.
> The data sheet for the HSMP-3822 has several ideas for getting very
> good isolation on the receiver side, once you've gotten isolation from
> the high power with a high voltagePINdiode, and there are otherPINdiodeap=
 notes on the Avago site.
>
> Cheers,
> Tom

Hi,Tom
   Thank you for your reply in my news group"how to design PIN diode
driver - high voltage and high speed ?"! I got so much in your answer!
   In my Antenna switch, in order to avoid input overload of my
receiver, a power limiter will be utilized. In your reply , you
mentioned that you also use PIN diode clamps on the input  to your
receiver . My question is , is it able to absorb transient voltage >1
mV (the maximum value of receiver's pre-amp is 1mV )? According your
suggestion , i am going to use HSMP-3822 diode pair with 5 volts
forward bias(when transmitting ),-5 volts reverse bias(when
receiving), on the input of my receiver. Do you think the power
limiter plan can absorb the transient energy above 1 mV for the
receiver during both the receiving state "ON" and "OFF"?
   Any suggestions will be appreciated!