Path: ...!Xl.tags.giganews.com!local-1.nntp.ord.giganews.com!nntp.supernews.com!news.supernews.com.POSTED!not-for-mail NNTP-Posting-Date: Fri, 07 Jun 2024 02:19:23 +0000 Subject: Re: AD5791 Newsgroups: sci.electronics.design References: From: Phil Hobbs Message-ID: Date: Thu, 6 Jun 2024 22:19:22 -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: 7bit Lines: 51 X-Trace: sv3-w1AzUwR3acJYKVPXyVOIyi247sgVlB7dgxgc85RXQgXeqFpIFNxNA4LQYZcevOovujYlMEF16g8vW79!olgGmUmJl/9y0/CmmkJlmStdjTcUdCTC2bYanLBkFPbgdfBh/tawPaxsKeYTTjN+OWcWbKPlhnEb!ggzBzzUxiJ1I+E+l4ZSg8s0= 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: 2829 On 2024-06-06 13:57, john larkin wrote: > On Thu, 06 Jun 2024 10:15:45 -0700, boB wrote: > >> On Tue, 04 Jun 2024 10:48:00 -0700, john larkin wrote: >> >>> https://www.analog.com/en/products/ad5791.html >>> >>> That's an amazing part. 20 bit DAC with 1 PPM accuracy and 0.05 PPM >>> per degree C tempco. >>> >>> My main gripe is its 3.4K output impedance, which makes a lot of >>> Johnson noise. I suppose I could run a bunch in parallel. >> >> >> Nice part but costs way too much for any products we make. >> >> boB > > What do you make? > > We live on the lunatic fringe of electronics, things that are really > hard to do, things with extreme exponents. It makes money because it > has little competition, but the money is a side effect. I do it > because it's fun. > > There must be something cool that we can do with a 1 PPM accurate DAC. > > TI has a 20-bit delta-sigma DAC that's about $12, but it's only linear > to 15 PPM. I don't understand how a d-s DAC or ADC can even be that > good. It would seem to need femtosecond edge accuracies inside. > I expect that the deterministic part of the jitter gets pushed out to high frequency by the noise shaping. Random jitter you'd have to deal with by averaging. 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