Re: MMICs (was Modamps)

Andy G4JNT

I think I'd agree, having also had only modest success using wafer scale chips.    In my case it was the AD8312 log-power detector.   Details of it, along with some photos are in June 2015 RadCom, page 40

That is a 1 x 2mm  Ball Grid Array package with 6 pads spaced about 0.5mm.  Connecting  BGA chips mandates reflow soldering - there's no hot iron option there -  and I did manage to do it after much effort.   However, only 50% success rate as I managed to break one of the devices though rough handling.    As Chris mentions, a vacuum pick-up is useful.   I'd had recommended a dampened wooden cocktail stick and that does work with small components but not with that larger device.   So the non-advised metal tweezers and sure enough, one chipped and damaged.    Other one works fine and I have a decent 3GHz power meter for the -50 to 0dBm region with line-of-LEDs display

So after reading Chris's comment below, won't bother ordering some to play with.   After pondering a bulk Mini-Circuits order, went instead for Mini-Kits (AU)  to stock up on a few ERA-1 for legacy stuff and some GALI-1 devices to try out.

The chip Sam mentions looks good too - next Minicircuits order, worth getting a few 

Andy  G4JNT

On 13 June 2016 at 10:07, Christopher Bartram cbartram@... [ukmicrowaves] <ukmicrowaves@...> wrote:

(The term Modamp has been obsolete for a very long while ...)

As I seem to be the only person on this list to have actually used the
VMMK-2203 (and also some other parts within that range) I can offer the
potential insight that I've stopped using them!

The devices work well (I used them in my 10GHz transverter boards) , but
despite having a great deal of experience working with SMD devices, the
chip-scale package is a complete pain to handle! It would be VERY
difficult to solder using even a very fine soldering iron. I never
succeded (and I use an ERSA soldering station with a 0.1mm bit for
working with 0402s). Reflow worked OK - most of the time. Also, the
package itself, being a liquid crystal is very fragile., and a vacuum
pick-up tool is essential.

I'm not sure if they are still currently manufactured.

Had I continued with the transverter, I planned to replace the VMMKs
with a (from memory) RFMD NBB310, even that, though, is a pretty
long-in-the-tooth part. However, over the last few months some other
devices have begun to appear which look even better, including some from
Mini-Circuits, but I've not had time to investigate them.

Vy 73



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