[hpsdr] Hittite c/o switch

[Chris Bartram]

> HAVE YOU considered the HMC174MS8
> I am only observing emails and not taking too close a look at the detail
> but I found some of these on ebay while looking for something else. This is
> a DC to GHz changeover switch made by Hittite with an IP3 typical of 60dBm
> and 0.5dB loss, 10nS switching.
> It might be irrelevant for various reasons but I thought I would draw your
> attention to it.

Be warned - while these switches have excellent performance above a few 
hundred MHz, the internal bootstrapping (which is necessary to get good 
linearity from FET switches) falls over below about 100MHz. I was working in 
this area about a year ago, and the only way - at least at that time, but I 
don't think it's changed - to get linearity in the +60dBm IPI3/+100dBm IPI2 
region is to use discrete devices. I'm afraid client confidentiality prevents 
me from revealing what to use and and how...

Chris
GW4DGU

-- 
Christopher Bartram MIET
Christopher Bartram RF Design
Blaenffos
Pen-y-Bont
CARMARTHEN
SA33 6QG

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