Microwave detector diode circuit..... What is the highest

[groundhog1]

What is the highest frequency that you can successfully build a detector diode circuit using packaged Surface Mount diodes? I know that for really high frequency operation, you have to transition to bare die. I just don't have a feel for what that frequency is.

Thanks,
groundhog

 

[VisiGoth]

You should be able to hit 18 GHz. There are proprietary sruface mountable sealed glass packages that may work well into the mm wave.

 

[IRstuff]

People built receivers for 35 GHz using packaged parts, back in the late 80's.

TTFN

 

[groundhog1]

Yes, I am getting from Agilent that they have SMT devices that will go to 10GHz and beam lead diodes that will work to 26GHz.

I am wondering if there is anything in between. The beam lead diodes are a little fragile, and I would like to hit up to 18GHz if possible.

groundhog

 

[pstuckey]

Take a look at Macom (

http://www.macom.com).

They have a large selection of diodes some surface mount, some die. One that may be of interest for your detector is MA4E2544L-1282.

 

[biff44]

Alpha used to make some millimeter wave devices that used good old fashioned axial lead glass packaged diodes. They placed the diode across the waveguide, with one lead going out of the top and the bottom going out the bottom wall of the waveguide. They had a simple capacitor choke where the lead went thru the waveguide wall.

 

[pstuckey]

BTW a couple years ago Alpha merged with another company (I forget who) and the combined company is now called Skyworks (

http://www.skyworksinc.com/).

They got rid of some of their mmwave amplifiers unfortunately, but I think they still offer Alpha's diodes.

 

[groundhog1]

That's good information. Thanks.

On the axial lead concept. It must have been a really small diameter pedistal they put the diode on because wouldn't the capacitance of that package short out the diode at high frequencies?

I looked at the macom part. Looks good.

Thanks,
groundhog

 

[biff44]

These were big diodes, like the type you would normally see soldered to a thru hole printed circuit board. I think they tuned them by moving them up and down in the waveguide, and when they were optimized, they soldered them in place at the top and bottom.