Looking for alternative to Silicon Labs SI4133 (PLL synthesizer with VCO, 2 GHz - Page 1
Forum section: electronics / rf-microwave

author: wb0gaz
author_rank: Frequent Contributor
timestamp: February 13, 2023, 04:55:12 pm
content: I'm looking for alternative to the SI4133 family RF synthesizer ICs.The SI4133 accepts a reference oscillator (typically CMOS, 13 MHz is common) and (specific to that part) uses an external SMD inductor (or PC trace loop) as part of the VCO, but otherwise is self-contained - program it with SPI port, and out comes RF (depending on the part, up to about 1800 MHz.) It runs off 3.3V and takes modest power (couple tens of milliamps). It has some track record in ham/hobby use, and is available in TSSOP package which isn't too hard to hand assemble.In searching online for an alternative (the SI4133 family seems at/near end of life), I've not found anything that is a clear alternative, presumably because much of the application base (cordless phones, satellite radio, etc.) has matured.If you have any ideas of a substitute (the only really mandatory thing is an onboard VCO and modest power consumption and accepts an external reference input, ruling out SI590 type parts), I'd like to know.Thanks,Dave

author: rfdave#gmail.com
author_rank: Contributor
timestamp: February 16, 2023, 03:38:26 am
content: Both analog devices and Texas instrument offer frequency synthesizers with integrated VCOs that might cover the bands you’re interested in.

author: Odysseus
author_rank: Regular Contributor
timestamp: February 17, 2023, 07:30:22 am
content: The ADF4351 is a common hobbyist PLL / synthesizer with good availability. Lots of turn-key eval boards on the market. Ebay and Amazon searches give lots of results. I need to buy a couple myself.

author: luiswen
author_rank: Newbie
timestamp: February 17, 2023, 11:43:29 am
content: Hi Dave, what's the SI4133 series full part number, i will try to find the alternative for you.Louis

author: wb0gaz
author_rank: Frequent Contributor
timestamp: February 17, 2023, 12:07:12 pm
content: The SI4133 most-common part number is SI4133-D-GT (D is a the more common/later version, G was the initial version, and GT means TSSOP20 package.)The TI/Analog offerings (of which there are many) are (as far as I can tell) invariably QFN-style (=difficult to hand solder) packages, and somewhat overkill as a rule (multiple VCO "cores" and such as they seek to have continuous coverage up to their respective ceiling frequencies.) The SI4133 was (is) more purpose built, mostly I think targeting things like cordless phones, where continuous coverage wasn't a requirement (SI4133 gets it's range from an external inductor, other than that it's VCO is internal.)Thanks very much for the helpful discussion, I really appreciate having "more eyes" on this question!Dave

author: switchabl
author_rank: Frequent Contributor
timestamp: February 17, 2023, 01:56:09 pm
content: Quote from: wb0gaz on February 13, 2023, 04:55:12 pmDo you have more info on that? I know that is has apparently been part of the Sykworks acquisition (https://investors.skyworksinc.com/news-releases/news-release-details/skyworks-completes-acquisition-infrastructure-automotive) and I wouldn't be totally surprised if they discontinued some older SiLabs parts. But so far it is not listedhereand both Mouser and Digikey have it in stock and listed as "active".