On Sun, 03 Apr 2022 03:30:27 -0400, time-nuts-requ...@lists.febo.com wrote: time-nuts Digest, Vol 216, Issue 4
> ------------------------------ > > Message: 6 > Date: Sat, 2 Apr 2022 07:36:27 -0700 > From: "Lux, Jim" <j...@luxfamily.com> > Subject: [time-nuts] Re: +1/f of transistors > To: time-nuts@lists.febo.com > Message-ID: <fa51db42-c572-810f-785c-3763ef25e...@luxfamily.com> > Content-Type: text/plain; charset=UTF-8; format=flowed > > On 4/2/22 3:31 AM, Leon Pavlovic wrote: >> Hello to all, >> >> as Gerhard already mentioned, the 1/f data of transistors is really a >> kind-of black magic stuff and almost never present in the datasheets. > > Not only that, but it potentially changes from lot to lot. > > Lately, I've been seeing papers using various microwave pHEMTs but, by > the time you find and read the paper, the part is no longer available. > And, of course, just like low noise MMICs (PGA-103, GALI-74) you have to > measure them yourself to find out - because the mfr only measures from > 50 MHz and up. It's a big problem. Nor do they specify DC parameters all that well. > A good example is the 2018 paper by Chen, et al. which references the > ATF54143 - a 3 year old paper, and the part isn't available any more. > The 2SK117 shows up a lot in some older articles and app notes (e.g. > from Wenzel) - it's discontinued, but potentially available from some > surplus/obsolete dealers. > > Exp Astron (2018) 45:231–253 <https://doi.org/10.1007/s10686-018-9576-3> > <https://link.springer.com/article/10.1007/s10686-018-9576-3> > > > There is a list in The Art of Electronics, but some of them won't be > available. Some datasheets do have the curve - the JFE150 from TI has > its voltage noise curve right on the front page. What those folk are currently using for capacitance multipliers and the like (where low 1/f noise is also essential) are SiGe transistors like the following: BFP640H (Infineon), BFP780, SAV541 (MiniCircuits), and 2S2114K (NPN, beta 1200) for high current applications. And the best choices do keep going obsolete. These have GHz gain-bandwidth products, and want to oscillate, so some base or gate resistance (often a ferrite bead) is necessary. There would be two applications in a low-noise oscillator. One would be as a capacitance multiplier to filter the Vcc provided to the oscillator circuit, giving considerable PSRR. The other would be in the oscillator circuit itself. Joe Gwinn _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.