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High speed pulse generator to test oscilloscope

Started by Unknown May 12, 2014
Greetings
I have a Tek TDS694C I will be selling, and I'd like to demo it's high speed 
performance by showing it detecting a rise time - I'm trying to remember exactly 
what that is - somewhere in picosecnd range?

Is there a chip which will show a fast rise time? I believe they use some kind of 
high speed fpga? 

thanks in advance
jb
On Monday, May 12, 2014 6:39:03 AM UTC-4, haitic...@gmail.com wrote:
> Greetings > I have a Tek TDS694C I will be selling, and I'd like to demo it's high speed > performance by showing it detecting a rise time - I'm trying to remember exactly > what that is - somewhere in picosecnd range?
It's something like, 1/3 or 1/pi times 1/bandwidth, so 1GHz is 300ps of something. There's a nice J. Williams article about fast edges/ pulses AN47? (maybe?) George H.
> > > > Is there a chip which will show a fast rise time? I believe they use some kind of > > high speed fpga? > > > > thanks in advance > > jb
On 12/05/2014 20:39, haiticare2011@gmail.com wrote:
> Greetings > I have a Tek TDS694C I will be selling, and I'd like to demo it's high speed > performance by showing it detecting a rise time - I'm trying to remember exactly > what that is - somewhere in picosecnd range? > > Is there a chip which will show a fast rise time? I believe they use some kind of > high speed fpga? > > thanks in advance > jb >
An old Philips 74LVC04 chip can do about 250ps risetime: http://www.youtube.com/watch?v=oUiEeOp8ynY#t=698s (It is Philips not TI as mentioned in the video.) Unfortunately that particular board didn't have sufficient low-frequency decoupling (it was intended for use at much higher frequencies where the decoupling was adequate), so the power supply cable inductance rings badly with the small decoupling capacitors on the board. If he had looked at the fall-time instead of rise time, and left my ac-coupling and back termination in, it might have been a bit cleaner. The best option would have been to improve the local low frequency decoupling, with some big caps. Chris
On Monday, 12 May 2014 20:39:03 UTC+10, haitic...@gmail.com  wrote:
> Greetings > > I have a Tek TDS694C I will be selling, and I'd like to demo it's high speed performance by showing it detecting a rise time - I'm trying to remember exactly what that is - somewhere in picosecnd range? > > Is there a chip which will show a fast rise time? I believe they use some kind of high speed fpga?
John Larkin is the expert here. When I had to do something similar - a long time ago - I used a well-specified step-recovery diode from HP. If you could find one in a low-inductance - which is to say, a small circuit mount - package, and mount it in a transmission line environment, above a good ground plane, you might have got down to a 100psec risetime. John seems to do better. Some ECLinPS parts are supposed to be in the same ball-park, and will drive 50R terminated transmission lines, as will a step recovery diode. -- Bill Sloman, Sydney
On 05/12/2014 10:33 AM, Bill Sloman wrote:
> On Monday, 12 May 2014 20:39:03 UTC+10, haitic...@gmail.com wrote: >> Greetings >> >> I have a Tek TDS694C I will be selling, and I'd like to demo it's high speed performance by showing it detecting a rise time - I'm trying to remember exactly what that is - somewhere in picosecnd range? >> >> Is there a chip which will show a fast rise time? I believe they use some kind of high speed fpga? > > John Larkin is the expert here. When I had to do something similar - a long time ago - I used a well-specified step-recovery diode from HP. > > If you could find one in a low-inductance - which is to say, a small circuit mount - package, and mount it in a transmission line environment, above a good ground plane, you might have got down to a 100psec risetime. > > John seems to do better. Some ECLinPS parts are supposed to be in the same ball-park, and will drive 50R terminated transmission lines, as will a step recovery diode. >
Well, the real answer of course is to hang onto the TDS694C, and get an 11801C and SD-24 TDR head to test it with. ;) Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
On Monday, May 12, 2014 10:35:54 AM UTC-4, Phil Hobbs wrote:
> On 05/12/2014 10:33 AM, Bill Sloman wrote: > > > On Monday, 12 May 2014 20:39:03 UTC+10, haitic...@gmail.com wrote: > > >> Greetings > > >> > > >> I have a Tek TDS694C I will be selling, and I'd like to demo it's high speed performance by showing it detecting a rise time - I'm trying to remember exactly what that is - somewhere in picosecnd range? > > >> > > >> Is there a chip which will show a fast rise time? I believe they use some kind of high speed fpga? > > > > > > John Larkin is the expert here. When I had to do something similar - a long time ago - I used a well-specified step-recovery diode from HP. > > > > > > If you could find one in a low-inductance - which is to say, a small circuit mount - package, and mount it in a transmission line environment, above a good ground plane, you might have got down to a 100psec risetime. > > > > > > John seems to do better. Some ECLinPS parts are supposed to be in the same ball-park, and will drive 50R terminated transmission lines, as will a step recovery diode. > > > > > > > Well, the real answer of course is to hang onto the TDS694C, and get an > > 11801C and SD-24 TDR head to test it with. ;) > > > > Cheers > > > > Phil Hobbs > > > > -- > > Dr Philip C D Hobbs > > Principal Consultant > > ElectroOptical Innovations LLC > > Optics, Electro-optics, Photonics, Analog Electronics > > > > 160 North State Road #203 > > Briarcliff Manor NY 10510 > > > > hobbs at electrooptical dot net > > http://electrooptical.net
hmmmm What is the tds64c god for, practically? jb
On Mon, 12 May 2014 10:35:54 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

>On 05/12/2014 10:33 AM, Bill Sloman wrote: >> On Monday, 12 May 2014 20:39:03 UTC+10, haitic...@gmail.com wrote: >>> Greetings >>> >>> I have a Tek TDS694C I will be selling, and I'd like to demo it's high speed performance by showing it detecting a rise time - I'm trying to remember exactly what that is - somewhere in picosecnd range? >>> >>> Is there a chip which will show a fast rise time? I believe they use some kind of high speed fpga? >> >> John Larkin is the expert here. When I had to do something similar - a long time ago - I used a well-specified step-recovery diode from HP. >> >> If you could find one in a low-inductance - which is to say, a small circuit mount - package, and mount it in a transmission line environment, above a good ground plane, you might have got down to a 100psec risetime. >> >> John seems to do better. Some ECLinPS parts are supposed to be in the same ball-park, and will drive 50R terminated transmission lines, as will a step recovery diode. >> > >Well, the real answer of course is to hang onto the TDS694C, and get an >11801C and SD-24 TDR head to test it with. ;) > >Cheers > >Phil Hobbs
Yeah, the TDR step (and the calibrator output) are metrology-class rising edges, in the 30 ps range. A lot of cmos chips will make pretty clean edges in the ballpark of 500 ps. NL37WZ16US is great, 11 cents, but the US8 package is nasty. DS90LV012ATMF is basically a r-r comparator with a 500 ps output. SOT23, reasonable to solder down on some hacked copperclad. The Onsemi Gigacomm parts can make really sweet edges down around 50 ps, but need to be handled very carefully, definitely not x-acto knife stuff. You can reasonably breadboard with EclipsLite and EclipsPlus parts https://dl.dropboxusercontent.com/u/53724080/Protos/BB_fast.JPG 225 ps typ rise/fall for that EL07. -- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation
haiticare2011@gmail.com wrote:
> Greetings > I have a Tek TDS694C I will be selling, and I'd like to demo it's high speed > performance by showing it detecting a rise time - I'm trying to remember exactly > what that is - somewhere in picosecnd range? > > Is there a chip which will show a fast rise time? I believe they use some kind of > high speed fpga? >
I guess a fall time would also count. How high is "high speed"? A simple BFR92 driven hard can give you fall times in the 100psec range. That would be a part that could already be in a parts bin somewhere. The BFS17 is good as well but it depends which kind you have. -- Regards, Joerg http://www.analogconsultants.com/
On 05/12/2014 12:07 PM, haiticare2011@gmail.com wrote:
> On Monday, May 12, 2014 10:35:54 AM UTC-4, Phil Hobbs wrote: >> On 05/12/2014 10:33 AM, Bill Sloman wrote: >> >>> On Monday, 12 May 2014 20:39:03 UTC+10, haitic...@gmail.com wrote: >> >>>> Greetings >> >>>> >> >>>> I have a Tek TDS694C I will be selling, and I'd like to demo it's high speed performance by showing it detecting a rise time - I'm trying to remember exactly what that is - somewhere in picosecnd range? >> >>>> >> >>>> Is there a chip which will show a fast rise time? I believe they use some kind of high speed fpga? >> >>> >> >>> John Larkin is the expert here. When I had to do something similar - a long time ago - I used a well-specified step-recovery diode from HP. >> >>> >> >>> If you could find one in a low-inductance - which is to say, a small circuit mount - package, and mount it in a transmission line environment, above a good ground plane, you might have got down to a 100psec risetime. >> >>> >> >>> John seems to do better. Some ECLinPS parts are supposed to be in the same ball-park, and will drive 50R terminated transmission lines, as will a step recovery diode. >> >>> >> >> >> >> Well, the real answer of course is to hang onto the TDS694C, and get an >> >> 11801C and SD-24 TDR head to test it with. ;)
> hmmmm What is the tds64c god for, practically?
It's my favourite general-purpose high speed scope. I have a couple of 500-MHz ones, which are about the fastest that still have the 1 Mohm input option, but for anything I can use 50-ohms for, or can hang a FET probe on, the 694C is the proverbial bee's knees. 125 ps rise time, no overshoot, whee! Mine has the 2Msample memory as well, which is a win, and a nice bright display. Sampling scopes require many triggers per waveform (512 in the case of the 11801 series), and can't look backwards in time before their triggers. (That's why the 11802 comes with two coiled hardline delay lines in the mainframe.) Sampling scope triggering is also external-only, which takes a bit of futzing around if you're not doing stimulus-response type measurements. The 11801 will give you a factor of 8 faster response than that with the ordinary plugins, and a factor of nearly 20 with the fastest ones. That's fast enough that you have to put the sampling head right at the circuit, which is where the extender cables come in. Cheers Phil "Scope junkie" Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
Den mandag den 12. maj 2014 15.06.00 UTC+2 skrev George Herold:
> On Monday, May 12, 2014 6:39:03 AM UTC-4, haitic...@gmail.com wrote: > > > Greetings > > > I have a Tek TDS694C I will be selling, and I'd like to demo it's high speed > > > performance by showing it detecting a rise time - I'm trying to remember exactly > > > what that is - somewhere in picosecnd range? > > It's something like, 1/3 or 1/pi times 1/bandwidth, so 1GHz is 300ps of something. > > > > There's a nice J. Williams article about fast edges/ pulses > > AN47? (maybe?) >
http://cds.linear.com/docs/en/application-note/an47fa.pdf http://cds.linear.com/docs/en/application-note/an72f.pdf -Lasse -Lasse