EEVblog #316 - More PFANG, More 13GHz Scope, & More Pulser - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: July 19, 2012, 01:48:47 pm
content: Dave.

author: KTP
author_rank: Frequent Contributor
timestamp: July 19, 2012, 03:32:32 pm
content: There are some comparitors with 50ps rise/fall timesThis paper talks about making a low cost fast rise time pulse gen:http://www.ise.pw.edu.pl/~tomi/papers/wilga2006_50ps.pdfThe ADCMP580 used in that discussion data sheet is here:http://www.analog.com/static/imported-files/data_sheets/ADCMP580_581_582.pdfSells for $18 at digikey...ouch.From the data sheet:"The ADCMP580/ADCMP581/ADCMP582 are ultrafast voltage comparators fabricated on the Analog Devices, Inc. proprietary XFCB3 Silicon Germanium (SiGe) bipolar process. The ADCMP580 features CML output drivers, the ADCMP581 features reduced swing ECL (negative ECL) output drivers, and the ADCMP582 features reduced swing PECL (positive ECL) output drivers.All three comparators offer 180 ps propagation delay and 100 ps minimum pulse width for 10 Gbps operation with 200 fs random jitter (RJ). Overdrive and slew rate dispersion are typically less than 15 ps.The ±5 V power supplies enable a wide ?2 V to +3 V input range with logic levels referenced to the CML/NECL/PECL outputs. The inputs have 50 ? on-chip termination resistors with the optional capability to be left open (on an individual pin basis) for applications requiring high impedance input."

author: veryevil
author_rank: Unknown
timestamp: July 19, 2012, 07:34:00 pm
content: Hey, The letter says that you should have used a 20Mhz SINE WAVE not square wave input! Guessing that would have cut down on the ringing.Now you have to build one and try it again!

author: SeanB
author_rank: Super Contributor
timestamp: July 19, 2012, 08:18:51 pm
content: I did something similar dead bug style to get a better clock out from a PC interface card. 54S14 dead bugged 4 high, with a 0.1uF across the top, and a 10uF 25V wet tantalum as well over that. Just used 1 inverter from the bottom to drive the 3 above it, and they in turn drove the rest of the inverters in parallel. Had no problem driving a 24MHz clock direct to 110R twinax with only end termination. Did run a little warm though, but the cerdip package was happy with that. If they had toasted I would have made another and would have added copper strip fins between the packages.

author: Nermash
author_rank: Frequent Contributor
timestamp: July 19, 2012, 08:36:04 pm
content: One thing intrigues me about that 13 GHz scope, I kind of expected to see SMA or more advanced sexless connectors on it (can't remember the name).From all the sources I have read, BNC is good only up to 3 GHz?

author: EEVblog
author_rank: Unknown
timestamp: July 19, 2012, 11:15:34 pm
content: Quote from: Nermash on July 19, 2012, 08:36:04 pmI was surprised too.But Agilent know what they are doing, so they clearly they have special ones that work to 13GHz.Dave.

author: LEECH666
author_rank: Frequent Contributor
timestamp: July 19, 2012, 11:21:30 pm
content: Dave, have you won the lottery recently? I wonder where all that super high end gear comes from.Cheers,Florian

author: Monkeh
author_rank: Super Contributor
timestamp: July 19, 2012, 11:22:47 pm
content: Quote from: LEECH666 on July 19, 2012, 11:21:30 pmLoaned for review, I believe.Do we get to see inside the obscenely expensive oscilloscope?

author: T4P
author_rank: Super Contributor
timestamp: July 19, 2012, 11:30:36 pm
content: Quote from: Nermash on July 19, 2012, 08:36:04 pmF connectorN connector

author: Monkeh
author_rank: Super Contributor
timestamp: July 19, 2012, 11:31:53 pm
content: Quote from: DaveXRT on July 19, 2012, 11:30:36 pmF? F?!

author: Lukas
author_rank: Frequent Contributor
timestamp: July 19, 2012, 11:42:49 pm
content: The NBSG series by OnSemi offer ~40 ps rise/fall times. They are horribly expensive around 50$ on digikey, but onsemi offers free samplesThe most difficult part in designing a pulse generator using a NBSG16 or so would be the PCB...

author: EEVblog
author_rank: Unknown
timestamp: July 19, 2012, 11:44:54 pm
content: Quote from: Monkeh on July 19, 2012, 11:22:47 pmAgilent heard I needed a high speed scope to measure the pulser, and they kindly loaned me one next day.Wasn't sent for "review".QuoteSorry, no, was asked not to take it apart. You can see some insides in the data sheet.I have some video of the "unboxing" in the garage, but not sure if anyone wants to see that. Probably just more complaints about Agilent owning the blogDave.

author: Monkeh
author_rank: Super Contributor
timestamp: July 19, 2012, 11:48:49 pm
content: Quote from: EEVblog on July 19, 2012, 11:44:54 pmAh. Not that they're uninterested in your comments (like touchscreens being annoying as hell).QuoteFair enough. And unboxing is a fairly boring process unless it's something which needs putting together.

author: free_electron
author_rank: Super Contributor
timestamp: July 20, 2012, 01:36:32 am
content: Quote from: EEVblog on July 19, 2012, 11:15:34 pmLook very closely at that connector. It is NOT a traditional bnc.- For starters there is no isolation sleeve around the center contact.- the center contact is not 2 pronged like in a classic bnc ( a tube sawed in two halves) but has a 6 prongs much like what you see on N connectors of their network analyzers.- If you look deep in the connectors you will not see the classic white plasitc or teflon isolation material but a yellowish material, almost like bare FR-4 material. That is Torlon. Works up to 45 GHz without problems.It looks like a bnc, and it mates with bnc, but it is a notably different construction... if you look a their HF mating probes that go up to those bandwidhts you will see a different construction there as well. These thing are more N-connector than bnc when it comes to the center pin.the sexless connector real name is APC-7. those go beyond 15Ghz... but need alcohol cleaning and a torque wrench to set... Amphenol Precision Connector 7 mmillimeter.the really high performance scopes like the 90000Q series use 3.5 mm connectors looks like a reverse SMA but is not quite the same ...Those scopes are really extreme.. up to 63GHz analog bandwidth... 160 Gigsamples per second and 2 gigapoints, yep GIGA not mega ! deep memory per channel....Read and cry your eye's out ...http://cp.literature.agilent.com/litweb/pdf/5990-9712EN.pdf- Indium phosphide chips ( silicon germanium is for grampa's and gallium arsenide for losers .... )- Can measure rise times as fast as 5pS ... you really need that to see wha tthe jim williams pulser can do ...- the probes have a 200GHz fT ...- has a built in 'calibrator' pulse rise time : 15pS .. eat that JW-pulser ...ah well, at half a million US$ for a base setup ...

author: Nermash
author_rank: Frequent Contributor
timestamp: July 20, 2012, 07:30:26 am
content: Thanks for the explanation, that is some very interesting info!

author: T4P
author_rank: Super Contributor
timestamp: July 20, 2012, 07:15:14 pm
content: Half a million! Wow!Sadly there's something more frightening in this world, than the scope agilent loaned to dave jonesA basic car for the UK people like the toyota's cost maybe 10k pounds or less?Over here it got so scary it costs at least 120,000 SGD at least! That's for an 13GHz 40GSa scope!

author: T4P
author_rank: Super Contributor
timestamp: July 20, 2012, 07:19:09 pm
content: Half a million! Wow!Sadly there's something more frightening in this world, than the scope agilent loaned to dave jonesA basic car for the UK people like the toyota's cost maybe 10k pounds or less?Over here it got so scary it costs at least 120,000 SGD at least! That's for an 13GHz 40GSa scope!Well a house way smaller than dave's house (or for reference, a 5rm flat that i have no idea how many sqft big it is)goes for 200,000 SGD at least more than the 20GHz 80GSa scope!(Read: A 5rm flat that is small but easily starts off at 700k! I want to live elsewhere ...)

author: blackdog
author_rank: Frequent Contributor
timestamp: July 20, 2012, 07:59:36 pm
content: So mutch mony en still 8 bit resolution

author: free_electron
author_rank: Super Contributor
timestamp: July 20, 2012, 08:19:19 pm
content: this gives you an idea of what this kind of beast is used for :http://www.home.agilent.com/agilent/redirector.jspx?action=ref&cname=AGILENT_EDITORIAL&ckey=2158864&lc=eng&cc=US&nfr=-11143.0.00&pselect=SR.GENERAL

author: SeanB
author_rank: Super Contributor
timestamp: July 20, 2012, 08:26:03 pm
content: Dave, you are welcome to come live in ZA, no problem at all.

author: SeanB
author_rank: Super Contributor
timestamp: July 20, 2012, 08:38:48 pm
content: Yup, ordered parts at previous work and saw the invoice. $100k each for power supplies........... They fit in the palm of your hand, and are about 150W each. Manufactured by Thompson CSF, now a part of Airbus Industrie.

author: Alexei.Polkhanov
author_rank: Frequent Contributor
timestamp: July 21, 2012, 04:05:10 am
content: Quote from: KTP on July 19, 2012, 03:32:32 pmIf I see what I see - they give a screenshot of 300mV signal with sharp rise time. What this kind of pulse is useful for? It won't even reach a threshold voltage of any laser diode in my possession :-) Many applications of pulse signals also require significant power to be delivered such as with 60-100V pulsers. That is the problem with all this pulsers built with fast logic devices for many practical applications such as lasers or time domain reflectometry kind of stuff you need more power.

author: T4P
author_rank: Super Contributor
timestamp: July 21, 2012, 06:03:59 pm
content: Quote from: SeanB on July 20, 2012, 08:26:03 pmI know i knowNice place and such but generally i am a little afraid of ZAQuote from: SeanB on July 20, 2012, 08:38:48 pm100k in SAR? That's a lotBut seriously, 500k here equates to 250 UK pounds

author: SeanB
author_rank: Super Contributor
timestamp: July 22, 2012, 08:06:45 am
content: Dave, you can literally stay for free......... 1 million refugees can't be wrong.I ordered and got 10 of these......... The price was in US dollars BTW,not ZAR. These did not even have a case, and were a component.

author: T4P
author_rank: Super Contributor
timestamp: July 22, 2012, 05:44:44 pm
content: Quote from: SeanB on July 22, 2012, 08:06:45 amjaw SMASHING

author: NiHaoMike
author_rank: Super Contributor
timestamp: July 24, 2012, 01:40:36 am
content: Those scopes are pretty popular where I work, and the reliability record is terrible! In the last few months, 5 Agilent scopes broke down out of the few dozen in the lab! For that reason, during critical work, they keep a spare on a cart, ready to be quickly swapped in at any time.

author: T4P
author_rank: Super Contributor
timestamp: July 24, 2012, 11:46:05 am
content: not when you are dealing with 13GHz of scope ...

author: deephaven
author_rank: Frequent Contributor
timestamp: July 24, 2012, 01:02:56 pm
content: If I had access to a PFANG and a 13 GHz scope I would seize the opportunity to do some practical tests on the behaviour of various PCB track configurations. There are no end of simulations etc for varying widths of tracks, with or without a ground plane etc. but it would be great to see some real life measurements. What can you get away with, what is critical and what doesn't make much difference. What effect does a small impedance mismatch have.

author: NiHaoMike
author_rank: Super Contributor
timestamp: July 26, 2012, 02:32:50 am
content: Quote from: DaveXRT on July 24, 2012, 11:46:05 amThe high end Tektronix scopes are a lot more reliable. But the Agilents are used a lot because they have the automatic testing software needed for a lot of the modern high speed interfaces.

author: T4P
author_rank: Super Contributor
timestamp: July 26, 2012, 08:31:32 am
content: Quote from: NiHaoMike on July 26, 2012, 02:32:50 amDPO70000 ? disadvantages about that agilent scope is in-reliability but it can be upgraded to 1Gpts anyway ... But the 400,000 wfrms min rate for the 90000a is interesting, much more than what the DPO70000 can do, 300,000 wfrms min ratewhile the tek scope is about 25k more expensive .. for the 12.5GHz model but also it's 10GS moreDo you know why the agilent is unreliable?

author: fcb
author_rank: Super Contributor
timestamp: July 27, 2012, 10:48:20 pm
content: It's not a PFANG, it's a PFAG - just read what Agilent wrote on the front of the unit.