John Larkin <jlarkin@highland_atwork_technology.com> wrote in news:mtlj9gda07sa2i1botgr4nga978cp6u8ug@4ax.com:> Well, RF people are not logical people. >Oh boy! Yet another Larkin totally retarded crack. Someone should stick a 10kW antenna up your ass and key up the mic for an hour. Fool modulation. Just like Mountain Dew... It'll tickle your innards!
digital capacitor
Started by ●April 15, 2021
Reply by ●May 10, 20212021-05-10
Reply by ●May 11, 20212021-05-11
On Tue, 11 May 2021 01:11:57 +0000 (UTC), DecadentLinuxUserNumeroUno@decadence.org wrote:>John Larkin <jlarkin@highland_atwork_technology.com> wrote in >news:mtlj9gda07sa2i1botgr4nga978cp6u8ug@4ax.com: > >> Well, RF people are not logical people. >> > > Oh boy! Yet another Larkin totally retarded crack. > > Someone should stick a 10kW antenna up your ass and key up the mic >for an hour. Fool modulation. > > Just like Mountain Dew... It'll tickle your innards!It was a pun. Lighten up.
Reply by ●May 12, 20212021-05-12
Simon S Aysdie wrote:> On Sunday, May 9, 2021 at 10:49:03 AM UTC-7, > jla...@highlandsniptechnology.com wrote: >> On Sat, 8 May 2021 17:35:50 -0700 (PDT), Simon S Aysdie >> <gwh...@ti.com> wrote: >> >>> On Friday, May 7, 2021 at 2:47:47 PM UTC-7, John Larkin wrote: >>>> On Fri, 7 May 2021 14:09:34 -0700 (PDT), Simon S Aysdie >>>> <gwh...@ti.com> wrote: >>>> >>>>> On Friday, May 7, 2021 at 11:16:34 AM UTC-7, John Larkin >>>>> wrote: >>>>>> On Fri, 7 May 2021 10:13:48 -0700 (PDT), Simon S Aysdie >>>>>> <gwh...@ti.com> wrote: >>>>>> >>>>>>> On Thursday, April 15, 2021 at 5:46:05 PM UTC-7, John >>>>>>> Larkin wrote: >>>>>>>> A few people make digital caps. This one is nice: >>>>>>>> >>>>>>>> https://www.mouser.com/ProductDetail/IXYS-Integrated-Circuits/NCD2100TTR?qs=npTsUczJOtNXvd3UFPIV7g%3D%3D >>>>>>>> >>>>>>>> >>>>>>>>I'm upgrading an oldish product that used a Maxim part that is, of>>>>>>>> course, discontinued. Maxim won't even acknowledge the >>>>>>>> old part number. Nobody in the world seems to have >>>>>>>> any. >>>>>>>> >>>>>>>> The Ixys part has three cap groups, coarse/medium/fine, >>>>>>>> with 10 bits total. The transfer function code to >>>>>>>> capacitance is sawtooth shaped, not monotonic, which >>>>>>>> guarantees that any cap value in the full range has >>>>>>>> some code that will hit it within one LSB. >>>>>>>> >>>>>>>> I'm coarse tuning an LC oscillator at powerup, to be >>>>>>>> close to 50 MHz, so that a varicap can take over and >>>>>>>> swing it to exactly 50. >>>>>>> >>>>>>> That's a neat looking part. Thanks. >>>>>>> >>>>>>> Peregrine also makes them. I have never had cause to use >>>>>>> them. None of them do what the Ixys part does, but the >>>>>>> option for series capacitance is there. >>>>>>> https://www.psemi.com/products/family/rf-phase-amplitude-control/digital-tunable-capacitors-dtcs >>>>>> >>>>>>>They do want RF- to be grounded. That's not very clear.>>>>>> >>>>>> I wonder why is has a min frequency rating of 100 MHz? >>>>> >>>>> Dunno. Maybe a similar reason to the Peregrine Si on Sapphire >>>>> switch's power rating that dives below 10 MHz. >>>> MiniCircuits has two very similar Phemts. One is specified for >>>> 0.45 to 6 GHz, and the other for 0.045 to 6 GHz. They both work >>>> fine at real DC; I use them as switches. >>>> >>>> Microwave people have weird ideas what they mean by "DC". >>> >>> DC is under 1 GHz. :) >>> >>>> I bought some absorptive RF switch ic's rated for DC-10 GHz, >>>> that didn't work below 100 MHz. Hittite I recall. >>>> >>>> Most "DC-to-xxGHz" rated microwave parts require input and >>>> output signal coupling capacitors. >>> >>> In that case "DC" means there are no internal DC blocks IN or >>> OUT. So, that means it will go as low as the DC blocks you put in >>> allow it to go. I am more annoyed by the opposite: when it has no >>> internal DC blocks yet they say it only goes down 50 MHz or so. >>> >>> A "DC" MMIC really does go down to DC. You just may not like the >>> built-in offsets. hah hah >>> >> A few honest people say LF instead of DC. > > By that logic, any transistor or Darlington should come with a low > frequency rating. > > The limit is in what you attach to it, not the device itself. That's > what they are telling you, and it is true, when they say "DC." >RF folks also care about impedance matching, which is typically quite different near DC. 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
