RF switches

[Jamie Morken]

Hi,

What are some good, low noise transmit/receive RF switches to use for
low power 2.4GHz ISM band? I haven't had much luck finding the SPM321
RF switches used in this circuit: (from a Nordic Semiconductor appnote)
"http://www.atgig.com/jmorken/poweramp.jpg"

Anyone know of some nice parts from TI, National, Maxim-ic etc that may
work well?

cheers,
Jamie

 

[Ken Taylor]

"Jamie Morken" <jmorken@shaw.ca> wrote in message
news:JWRie.1215$on1.92@clgrps13...

Hi,

What are some good, low noise transmit/receive RF switches to use for low
power 2.4GHz ISM band? I haven't had much luck finding the SPM321 RF
switches used in this circuit: (from a Nordic Semiconductor appnote)
"http://www.atgig.com/jmorken/poweramp.jpg"

Anyone know of some nice parts from TI, National, Maxim-ic etc that may
work well?

cheers,
Jamie

Checked out MiniCircuits?

Ken

 

[John Larkin]

On Thu, 19 May 2005 01:26:01 GMT, Jamie Morken <jmorken@shaw.ca>
wrote:

Hi,

What are some good, low noise transmit/receive RF switches to use for
low power 2.4GHz ISM band? I haven't had much luck finding the SPM321
RF switches used in this circuit: (from a Nordic Semiconductor appnote)
"http://www.atgig.com/jmorken/poweramp.jpg"

Anyone know of some nice parts from TI, National, Maxim-ic etc that may
work well?

cheers,
Jamie

Check out Hittite and NEC, too.

John

 

[Joerg]

Hello Jamie,

As John mentioned NEC may have suitable devices. Check out their UPG series.

Other than that, how about PIN diodes? These make fantastic RF switches
but they do require a few mA for a "closed switch".

Regards, Joerg

http://www.analogconsultants.com

 

[Jamie Morken]

Hi,

Joerg wrote:

Hello Jamie,

As John mentioned NEC may have suitable devices. Check out their UPG
series.

Other than that, how about PIN diodes? These make fantastic RF switches
but they do require a few mA for a "closed switch".

I found a couple of these at digikey but am not sure if they are
suitable for 2.4GHz operation:
MA2JP0200LCT-ND
MMBV3700LT1OSCT-ND

I checked out the Mini-Circuits GSWA-4-30DR, but it is listed at $20
each, and these PIN diodes from digikey are under a dollar each!

How would the pin diodes be layed out for transmit/receive switching,
similiar to this circuit:
http://www.atgig.com/jmorken/poweramp.jpg

How many PIN diodes would be required?

cheers,
Jamie

Regards, Joerg

http://www.analogconsultants.com

 

[Ken Taylor]

"Jamie Morken" <jmorken@shaw.ca> wrote in message
news:MW5je.5604$tt5.3701@edtnps90...

Hi,

Joerg wrote:
Hello Jamie,

As John mentioned NEC may have suitable devices. Check out their UPG
series.

Other than that, how about PIN diodes? These make fantastic RF switches
but they do require a few mA for a "closed switch".

I found a couple of these at digikey but am not sure if they are suitable
for 2.4GHz operation:
MA2JP0200LCT-ND
MMBV3700LT1OSCT-ND

I checked out the Mini-Circuits GSWA-4-30DR, but it is listed at $20 each,
and these PIN diodes from digikey are under a dollar each!

Minicircuits have already gone to the trouble of putting the PIN diodes into
a package and making it work. Depends how much your time is worth, or how
much fun you can have for your money.

How would the pin diodes be layed out for transmit/receive switching,
similiar to this circuit:
http://www.atgig.com/jmorken/poweramp.jpg

How many PIN diodes would be required?

cheers,
Jamie

The Minicircuits website has data on the devices, including the circuits for
the devices themselves, showing exactly what you want. See:
http://www.minicircuits.com/dg03-214.pdf

Cheers.

Ken

Regards, Joerg

http://www.analogconsultants.com

 

[Joerg]

Hello Jamie,

How would the pin diodes be layed out for transmit/receive switching,
similiar to this circuit:
http://www.atgig.com/jmorken/poweramp.jpg

The old HP app notes are really good. Examples on how to arrange PIN
diodes can be found in these notes, such as:

http://www.qsl.net/n9zia/wireless/pdf/An1072.pdf

For some reason it has become tough to find some of the HP app notes on
the Agilent server (sigh...) so it may be better to use Google.

How many PIN diodes would be required?

It depends on whether you want to do SPST, SPDT or a larger mux. Also,
it depends on off isolation requirements. For mundane stuff a single
diode in the RF path might do, for higher isolation a T-switch with
three diodes is favorable.

With respect to cost, check out other mainstream suppliers as well. I
have designed with PIN diodes that were more in the penny range rather
than a Dollar. They are not always called PIN diodes. Occasionally
marketeers prefer to label them "band switching diodes" and the like.

Of course, at 2.4GHz strict RF layout guidelines apply.

Regards, Joerg

http://www.analogconsultants.com