Path: ...!Xl.tags.giganews.com!local-2.nntp.ord.giganews.com!nntp.supernews.com!news.supernews.com.POSTED!not-for-mail NNTP-Posting-Date: Mon, 10 Jun 2024 19:14:40 +0000 Subject: Re: A collection of monographs on high accuracy electronics Newsgroups: sci.electronics.design References: <33c76j1cr78uhuk3djabivck4gbpe4dq9i@4ax.com> <6djc6jhurdaoqkvgnp0rcb1f4tci4da5pm@4ax.com> From: Phil Hobbs Message-ID: <5a46f302-382b-12de-f41d-61335179fe63@electrooptical.net> Date: Mon, 10 Jun 2024 15:14:40 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Lines: 122 X-Trace: sv3-D2PFEekb4sdsup8QMo8bIDCV24Sg56x/FaaxCbdDDAoADe8qMVulzrrSZx+Q2pUoNl0vNdGulkYECSk!uAtDtF71p95JMEWR/drFYTpur9UBcNwC4XnPLWKdkcJqlVDACvSwDUsyefbWb11AFr69i1ZI9i47!5Jxc7PNJItuMXN8GAM/Dx34p X-Complaints-To: www.supernews.com/docs/abuse.html X-DMCA-Complaints-To: www.supernews.com/docs/dmca.html X-Abuse-and-DMCA-Info: Please be sure to forward a copy of ALL headers X-Abuse-and-DMCA-Info: Otherwise we will be unable to process your complaint properly X-Postfilter: 1.3.40 Bytes: 5406 On 2024-06-09 21:43, Phil Hobbs wrote: > On 2024-06-09 20:55, JM wrote: >> On Mon, 10 Jun 2024 00:29:17 -0000 (UTC), Phil Hobbs >> wrote: >> >>> JM wrote: >>>> On Sun, 9 Jun 2024 18:09:24 -0000 (UTC), Phil Hobbs >>>> wrote: >>>> >>>>> Jeroen Belleman wrote: >>>>>> On 6/9/24 19:02, ehsjr wrote: >>>>>>> On 6/7/2024 9:14 PM, JM wrote: >>>>>>>> A collection of monographs on high accuracy electronics written >>>>>>>> by Mr. >>>>>>>> Chris Daykin, following his career predominantly in metrology. >>>>>>>> >>>>>>>> Unfortunately Chris will be unable to complete the unfinished >>>>>>>> monographs (having started end of life care) but there is plenty of >>>>>>>> interest to any analogue engineer. >>>>>>>> >>>>>>>> https://1drv.ms/b/c/1af24d72a509cd48/EZhO_rP5-glDmxtc4ZHycvYBhrsqmyC5tuZjt2NFFsS0gQ?e=Wq2Yj0 >>>>>>>> >>>>>>> >>>>>>> >>>>>>> Thanks! >>>>>>> Ed >>>>>> >>>>>> I have an issue with his definition of resistor noise power >>>>>> as the product of open-circuit noise voltage and short-circuit >>>>>> current. That makes no sense. >>>>>> >>>>>> There's more than that, probably, but that just jumped out at >>>>>> me. >>>>>> >>>>>> Jeroen Belleman >>>>>> >>>>> >>>>> It?s four times too high, for a start. >>>>> >>>>> Cheers >>>>> >>>>> Phil Hobbs >>>> >>>> "It is shown elsewhere [1] that the noise power is four times the heat >>>> energy which would flow down the conductors >>>> from a warm source resistor to a matching cold resistor." >>>> >>> >>> Which, if true, would solve all our energy problems, except that >>> thermodynamic systems would all be unstable. >>> >>> The thermal noise power produced by a resistor into a matched load is kT >>> per hertz. > >> >> Sure, which is what he states.  By mentioning a hot and cold resistor >> he makes it clear that net energy flow is from hot to cold, and that >> the T refers to the hot source. >> > But apparently he says that it's four times larger than that. > > I'm not making a microsoft account just to download the PDF, so if you > want to discuss it further, you could email it to me. > > Cheers > > Phil Hobbs > > > Bill was kind enough to send me a copy (thanks again, Bill), and right there on P. 374, the author says, Pn = 4kTB which is a factor of four too high. Twenty years ago I posted a brief derivation of the Johnson noise formula in the thread "thermal noise in resistors - Baffled!", as follows (with a couple of typos fixed). > One good way of deriving the Johnson noise formula (the sqrt(4kT) thing) > is from classical equipartition of energy. The stored energy in a > capacitor is a single classical degree of freedom, and hence (when > connected to a thermal reservoir, e.g. connected in parallel with a > resistor at temperature T) has a mean energy of kT/2, and since the > energy is CV**2/2, its rms noise voltage is sqrt(kT/C). > > The noise bandwidth of a one-pole RC lowpass is (pi/2)*(3 dB BW) = > 1/(4RC). Therefore, the noise power spectral density in the flatband is > > p_N=(kT/2C)*(4RC) per hertz, > > so setting p_N=C(e_N)**2/2, we get > > (e_N)**2 = kT*4R > > and > > e_N = sqrt(4kTR) per root hertz. > > This is the same noise that correlated double sampling in CCDs was > designed to deal with. The advantage of this way of looking at it is > that the resistor doesn't have to be linear--CMOS reset switches behave > the same way. > Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com