What's the prototyping board you're using?
This is a SP3T-50x50-G from BusBoard Prototype Systems. It has a copper plane on the bottom side, 50x50 mils pads on the top side and non-plated holes every fifth pad or so. It is a thin PCB, can be cut using a paper scissor.
I've been using the LTC6957 demo board. Unfortunately I'm in the middle of moving house (again) so everything is packed up so can't show anything other than this very bad photo.
The rise times for LVCMOS output is around 700 to 800 psecs and much less for the LVPECL version.
http://www.linear.com/product/LTC6957-1
This is a SP3T-50x50-G from BusBoard Prototype Systems. It has a copper plane on the bottom side, 50x50 mils pads on the top side and non-plated holes every fifth pad or so. It is a thin PCB, can be cut using a paper scissor.
Very nice, I'm sure I'll be adding a couple of those onto my next Mouser order.
Edit: do they spec the Er?
This is a SP3T-50x50-G from BusBoard Prototype Systems. It has a copper plane on the bottom side, 50x50 mils pads on the top side and non-plated holes every fifth pad or so. It is a thin PCB, can be cut using a paper scissor.
Very nice, I'm sure I'll be adding a couple of those onto my next Mouser order.
Edit: do they spec the Er?
I would have thought that the variability of anything you would use as conductors on the topside would be more significant than the likely difference in Er. I'd simply assume 4.2.
Hi,
I have discovered that BG7TBL's
35M-4.4G USB Signal Source (based on ADF4351) generates a quite nice square wave with fast edges around 200ps.
Measured with my TDS520B-500MHz (in fact ~650MHz --> Tr=~538ps)
Michel.
Don't really have a fast pulse generator, but I can show some relatively fast rise time on my RF gen.. as captured by the RTM 1054
I can reliably see the signal up to 1.2Ghz.. even up to 1.8Ghz is somewhat visible but the trigger starts failing pretty often at that frequency.
Thank you all for the postings. I just got the Siglent SDG2042X, at 1Mhz the square wave is acceptable, at 5Mhz starting to degrade very bad, etc. I thought I got a defective device. I need to dig more into how these things works. How the square wave is generated, etc. Reading your post helped me understand that I did not get a defective generator.
Thank you all for the postings. I just got the Siglent SDG2042X, at 1Mhz the square wave is acceptable, at 5Mhz starting to degrade very bad, etc.
Might get better results with ARB mode=DDS and using square from built in ARB wfms.
Heard a colleague say "now that's a fast edge"
ADT123,
was that sampling scopes one of your projects? Having a go at building a sampling scope has always been something I have wanted to try. The principles are so simple, but I am sure it took a massive effort to get that 25MHz bandwidth. The waveform really is amazingly clean.
Historically, this is the technology that allowed scopes to be built with GHz bandwidths when scope mainframes were struggling to reach even 1 MHz bandwidth.
A pity the price is so out of reach of the hobbyist. I have always thought this is potentially a very cheap technology if the market was big enough - maybe not for 25GHz, but 5GHz bandwidth would be pretty good.
Am I delusional?
Richard.
Here are my results of measuring a 10 MHz squarewave from my Siglent SDG1010 with three different bnc cables .
I know nothing about tech side... but as a concept, maybe it is possible to hack analog frontend of cheap USB scope having ETS? For example ~100EUR Pico 2204A has 2GSa/s ETS listed. Logically software is there, timing stuff is there...
Heard a colleague say "now that's a fast edge"
That looks like a fast rise time but to keep things apples to apples most of the measurements here have been at 10% and 90% rather than 20% and 80%.
Richard - I designed most of the real time scopes with a parallel port starting with the ADC-10 in 1991 and hung up my soldering iron around 2001 with the ADC212/100 which included repetitive ETS sampling (
https://www.picotech.com/about/history).
As for a lower cost / lower bandwidth sampling scope its an interesting idea. Above a few GHz every component gets expensive if you want to do the job properly (connectors, PCB etc) but below say 5GHz things get a lot cheaper. Will have a think. Guess it depends on the market - hobby users often go for 2nd hand boat anchors which can be cheap and to be honest not everyone knows how to drive a sampling scope (splitters for trigger signals etc).
10/90 vs 20/80 rise time - thats a fair cop. I just borrowed a waveform so when I get a chance will see if I can do better.
Tabor 8025, programmed to be 1Vpp, 50 MHz, 50 ohm terminated. 10%/90% rise time is 5.2ns, fall is 4.65ns.
10/90 rise time (see comment from Electro Fan a couple of posts again). Scope rise time is 14ps, pulse rise time is 10ps. Combined gives 18.74ps.
Please dont try to beat this - not sure I can respond with anything faster!
Noticed that on last Pico screenshot sampling rate is mere 10TSa/s, while on previous 16TSa/s
But guess both are adequate being "slightly" over Nyquist
10/90 rise time (see comment from Electro Fan a couple of posts again). Scope rise time is 14ps, pulse rise time is 10ps. Combined gives 18.74ps.
Please dont try to beat this - not sure I can respond with anything faster!
It is very competitive with the best rise time we have previously seen (~16ps by EV):
https://www.eevblog.com/forum/testgear/40-ps-rise-time/msg935446/#msg935446
Maybe someone can show us a sub picosecond rise time?
Not fast - Siglent SDG5082
50 Ohm output, 50Ohm pass through terminator on scope.
Not too horrible for ECL logic feeding multiple sources.