another RF part rant

When I designed this PA I just did a load line match per Steve Cripps. The Celeritek data sheet was one page. A spice model was not really necessary.

The evil phrase there is "pre-matched'.

Cheers

Phil Hobbs

What was the frequency range?

I worked with Metricom for a while, when they still wanted to do electrical metering. My impression, which aligns with this rant, is that they were mostly RF engineers and didn't much care about low stuff like 60 Hz.

Smart meters are a giant business now, and other things made their Ricochet idea obsolete.

And, basically, fiddle with the bias until it works.

"Pre-matched" usually means they have tweaked the wire bonds to resonate parasitics in some RF band, which wrecks time-domain behavior. This one claims "DC to 1.7 GHz" and "The device can support pulsed and linear operations" which imply time-domain uses. Maybe they still mean pulsed RF.

Maybe I can cage a sample.

Are those coaxial ceramic resonators up top? They can be useful in time domain too.

John, it has been more than 20 years. lol. I mean, it had to cover the 915 ISM band (~3%). It was well wider than that, of course, but "wide" is definitional and I don't recall. There was no particular attempt to make it narrow. Regardless, the Metricom radios were narrowband in fundamental requirements, as are most communications requirements.

Our power supplies were energized by 60 Hz. We loved 60 Hz. But seriously, the IFs were bandpass sampled at 6 MHz for the 900 radio and 8 MHz for the 2400 radio. No, low frequency performance was not a concern with this particular part.

I counted my blessings on having a great part available, sparse part data notwithstanding. 20 dB of gain and 4 W of power at 900 MHz seemed good to me at the time. Low frequency performance, aside from stability questions, was not important to the task at hand. So, you're right about that.

IIRC, Schlumberger bought the metering part from them as they went whole hog into the Ricochet thing. I mean, Ricochet was not the metering part of the business.

Yes. They were Transtech and/or Toko as were both on the AVL, IIRC.

I mean, I am referring to the little ones. The giant ones (12 mm) up top are in the ComNav preselector. ComNav has exceptional Q because of their plating process. For a long time they were th only vendor who could meet specs. Eventually IMC in San Diego managed to meet the requirements. So we had ComNav from Maine and IMC from San Diego.

Qorvo confirms that there are no DC curves nor a Spice model.

Odd to publish surface temp rise data above 200C for a part that is epoxy-sealed.

RL

Supposing you do manage to figure it out, chances are that Qorvo will then EOL it. lol