Show us your square wave

[JohnG]

Ok, so it's not the fastest, but it's pretty fast. It's also driving 5V into a 50 ohm load.

Texas Instruments LMG1020 gate driver in BGA package driving 50 ohms, measured with a Tek DPO7354C. Room for improvement on connection to SMA, but not bad. The chip has separate pull-up and pull-down outputs, and the resistors connecting the chip outputs to the transmission line are 1 ohm resistors in 0402 packages.

Cheers,
John

[Alfons]

Here is a screenshot of a signal from an ADF4351. I've gotten that part in order to better calibrate the MCP CRT of a 2467B in high frequencies. When programming with the arduino and testing, I was amazed to see that the part has quite fast rise times. Or do I understand something wrong, does the device measure wrong?

[Alfons]

I have just converted the TDS744a in a TDS784a, which was done without problems. The bandwidth has doubled. Here is a picture of the same signal as yesterday. You can see how a narrow bandwidth smoothes the signal.

[guenthert]

I have just converted the TDS744a in a TDS784a, which was done without problems. The bandwidth has doubled. Here is a picture of the same signal as yesterday. You can see how a narrow bandwidth smoothes the signal.

  While fundamentally one can expect a signal sampled with higher sample rate to produce a trace which better reflects said signal, in the examples given, there are enough sample points using the lower sample rate to show those 'humps' (harmonics) seen in the second trace.  I rather think those are two different signals.  Perhaps insufficient grounding in one?

  Ah, strike that.  Somehow I read 'bandwidth' you wrote as 'sample rate' (I'm having my coffee now).  If indeed the bandwidth of the low pass filter on the input got risen, you'd expect the different traces you got.  Don't mind me then.

[AVGresponding]

Sorry, couldn't resist   

[0culus]

I have just converted the TDS744a in a TDS784a, which was done without problems. The bandwidth has doubled. Here is a picture of the same signal as yesterday. You can see how a narrow bandwidth smoothes the signal.

I have an ADF4351 based signal generator evaluation board, and it looks fairly similar to that on my 7104. Really fast edges (I beat it by constructing a Jim Williams pulse generator though) but generally very ugly even with proper termination. 

[Alfons]

I have just converted the TDS744a in a TDS784a, which was done without problems. The bandwidth has doubled. Here is a picture of the same signal as yesterday. You can see how a narrow bandwidth smoothes the signal.

I have an ADF4351 based signal generator evaluation board, and it looks fairly similar to that on my 7104. Really fast edges (I beat it by constructing a Jim Williams pulse generator though) but generally very ugly even with proper termination. 

It would be overkill for me to get me a generator that produces clean signals to about 1 Ghz. But you can use that to test equipment. That's how I got the part. With a little skill you can use it to repair and calibrate equipment, because after all, the frequency is relatively stable to 1 Ghz and the frequency is also relatively accurate. Otherwise, I would not know what to do with it, because RF is not my area.

[0culus]

I originally bought the board because I needed a just over 3 GHz CW source that was juuust beyond what my 8664A could provide. I now have an 8672A 2-18 GHz signal generator, which obviously completely outperforms the eval board in virtually every relevant spec, especially phase noise.

[tautech]

Square waves from SDG6022X (80 MHz max) and SDG2042X (25 MHz max)
Taken with SDS5104X, Siglent 1 GHz rated BNC cable and feedthrough 50 ohm for the SDG2042X 10V p-p screenshot. All other shots using scopes inbuilt 50 ohm input.

[Mechatrommer]

few months ago verification... Rigol DS1054Z...





old Lecroy SDA6000...

[Electro Fan]

few months ago verification... Rigol DS1054Z...





old Lecroy SDA6000...

That looks like a very fast Rigol 1054Z

[Mechatrommer]

That looks like a very fast Rigol 1054Z

thats look like it but i dont know, thats what it said... i'm also a bit surprised... (tested with Leo Bodnar 30-40ps pulser) iirc that shape only happened on that V/div setting. if i increase (or decrease, dont really remember) when the relay clicked, that shape will be screwed... so i'm not sure whats going on inside there.

this is from another source tested much earlier (Uni-T UTG962 AWG Synch output)..

[Electro Fan]

That looks like a very fast Rigol 1054Z

thats look like it but i dont know, thats what it said... i'm also a bit surprised... (tested with Leo Bodnar 30-40ps pulser) iirc that shape only happened on that V/div setting. if i increase (or decrease, dont really remember) when the relay clicked, that shape will be screwed... so i'm not sure whats going on inside there.

this is from another source tested much earlier (Uni-T UTG962 AWG Synch output)..

Your measurements look like the Rise Time measurements but I can't quite figure it out.

As a frame of reference attached are a couple measurements made with Leo Bodnar's pulser; the LB pulser is spec'd for 30ps but I don't see how that can be achieved unless a scope can keep up.

The first two attachments show a Rigol 2072 spec'd for 70 MHz but that probably achieves a bit over 100 MHz - maybe at -3dB given the measured rise time of about 3.3 ns, and a Tektronix 2467B spec'd for 400 MHz which would imply a 875 ps rise time but that is measured at about 824 ps which implies a bandwidth of about 425 MHz.

In the attached chart are calcs for the 2072, the 2467B, and the 1054Z; these show that your 700 ps RT equates to a 500 MHz bandwidth and your 500 ps RT equates to a 700 MHz bandwidth.

Attached is an old spec sheet that shows some published numbers for a Tektronix 2465 and 2465A and my calculations (using the standard .35 formula) seem to arrive at similar numbers as a sanity check....
https://www.testequipmentdepot.com/usedequipment/tektronix/oscilloscopes/2465series.htm#:~:text=Increase%20in%20bandwidth%20from%20300,delay%20measurements%20(with%20CTT%20Option)

...but it's getting late here so I'm thinking maybe I've made some calc errors; however, if my numbers add up and yours are correct, I think you might have the fastest 1054Z known to mankind.

[Fungus]

That looks like a very fast Rigol 1054Z

thats look like it but i dont know, thats what it said... i'm also a bit surprised...

Plenty of people have seen similar results with the right cables, termination, etc.

(it's buried somewhere in the massive Rigol thread....)

[Electro Fan]

After looking at your Rigol posts and my Rigol while playing with the cursors, I think there is an error in the way we are I am using/interpreting the cursor measurements. 

I think your AX numbers of -800 and -500 ps are the distance to the left of the trigger line, and your BX numbers of 700 ps and 1.3 ns are the distances to the right of the trigger line. 

Try using the built-in Rigol Rise Time measurement and see if you get a number that is different than what your AX and BX cursor measurements are displaying. 

The BX-AX is more likely the Rise Time.

I got mesmerized by looking at ps measurements; I'm guessing what the Rigol cursor measurements are trying to tell us is that the Rise Time is 1.5 ns to 1.8 ns which would imply about 233 MHz to 190 MHz - still very fast for a 1054Z but somewhat more plausible.

Try the Rigol built-in Rise Time measurement and let us know.  My bad for even raising the issue.  Sorry. 

[Electro Fan]

Attached is a file showing the 2072 Rise Time of 3.3 ns.

Note that the B->X = 2.000ns display just happens to be highlighted because the cursor menu selection was set to SelectCursor X and CursorB.  So your eye is drawn to what is highlighted; makes sense except that if what you are really looking for is DeltaX (what I think is the Rise Time), then you might be (in my case, at least) temporarily confused.   

On the 2072 Rigol uses the convention DeltaX and on the 1054Z Rigol uses the BX-AX convention.  These are nitty little things but either way until you are fully indoctrinated (or at least paying attention, duh), it's possible to misinterpret a displayed value.  All good lessons that I'm happy to have learned.    

And, I'm still leaving open the possibility that I'm still missing something.....  so feel free to point it out.... I heard someone say recently we learn much more from our mistakes than when we get it right.  I'm feeling like I'm continuously in the deep end of the learning pool. 

Slightly veering off topic but I just noticed... doesn't seem like the Rigol 2072 display shows the 10% and 90% markers that would be nice to have for RT measurements.

[T3sl4co1l]

Not having seen the settings, acquisition and all that -- it could easily just be a glitch, with sinc interpolation making it look believable.  (The suspiciously small number of points seems to hint at that?)

I can do the same thing, to literally unbelievable risetimes, on my TDS460 -- this being relatively easy as it uses equivalent time sampling.  (Heh, though I don't know how I'd trick it to acquire a nice step; it's random sampling I believe, it just assembles a waveform bit by bit.)

Heh, and at maximum settings (1ns/div sweep, 50x zoom), it can show all the way down to 20ps/div.  Not that anything it can properly acquire is at all meaningful there (it's only 350MHz BW).

Tim

[graybeard]

This is the output of my 1GHz Colby PG100A pulse generator running at 200 MHz into my 1GHz Tektronix TDS784D.  The Colby (with GaAs drive option) is rated for a rise and fall time of <250ps, so the times shown are a limitation of the scope.











Click on the images above for a larger version.

Chris

[Electro Fan]

Not having seen the settings, acquisition and all that -- it could easily just be a glitch, with sinc interpolation making it look believable.  (The suspiciously small number of points seems to hint at that?)

I can do the same thing, to literally unbelievable risetimes, on my TDS460 -- this being relatively easy as it uses equivalent time sampling.  (Heh, though I don't know how I'd trick it to acquire a nice step; it's random sampling I believe, it just assembles a waveform bit by bit.)

Heh, and at maximum settings (1ns/div sweep, 50x zoom), it can show all the way down to 20ps/div.  Not that anything it can properly acquire is at all meaningful there (it's only 350MHz BW).

Tim

With all due respect, I don't believe we were looking at a "glitch".  It was just a mis-read/misinterpretation of the the cursor readout values.


Edit:  added some photos... original at 700 Pts (what the Rigol chose on Auto) and same waveform from same pulse gen showing same cursor display values at 1.4 MPts, 14 Mpts, and 56 Mpts.  The whole discussion of why Mechatrommer's 1054Z seemed so blindingly fast was because I got us off track when I saw numbers like 700 ps and 500 ps*; it was just me looking at the displayed values (values that at first I thought were Rise Times but I'm now pretty sure are just the deltas to the trigger line).  So these values weren't intended to be interpreted as Rise Time values, that was just my error.  It certainly wasn't anything Mechatrommer did or misinterpreted; he just posted his results.  His posts were A-OK/perfecto and I think his 1054Z is A-OK/normal, ie, very fast for a 1054Z but not fundamentally different than other 1054Zs we've seen.

*I can't help it, I get excited when I see anything with picoseconds 

[Mechatrommer]

if my numbers add up and yours are correct, I think you might have the fastest 1054Z known to mankind.

i think mine is just normal like everybody else rigloled to 100MHz, i suggest someone try the setting, 500mV/div, sinc(always on cant turned off of course), peak acq.. reducing to 200mV/div signal will be distorted similar to your shown 2072 signal.. i smelled ifft effect since there's slightly gibbs phenomenon visible on my signal, i was just enjoying the squareness of it without giving much thought on RT figure. I did check with my erasynth micro last night after you brought this up, the -3db signal bw of my 1054z is just about 270MHz... so no magic there.. i forgot ds1054z has a risetime meas built in, i'll try that later if i remember, now in office and lack of sleep.

[Electro Fan]

Not having seen the settings, acquisition and all that -- it could easily just be a glitch, with sinc interpolation making it look believable.  (The suspiciously small number of points seems to hint at that?)

I can do the same thing, to literally unbelievable risetimes, on my TDS460 -- this being relatively easy as it uses equivalent time sampling.  (Heh, though I don't know how I'd trick it to acquire a nice step; it's random sampling I believe, it just assembles a waveform bit by bit.)

Heh, and at maximum settings (1ns/div sweep, 50x zoom), it can show all the way down to 20ps/div.  Not that anything it can properly acquire is at all meaningful there (it's only 350MHz BW).

Tim

With all due respect, I don't believe we were looking at a "glitch".  It was just a mis-read/misinterpretation by me/EF of the the cursor readout values.
edited to clarify it was my error

i was using manual cursor and calculation to get 10 and 90% level, and criss cross intersect the vertical cursors to get risetime. As said i forgot there is built in risetime math i'll try that later...

- just to confirm, this was my (Electro Fan's) error caused by my mis-read on the values displayed, it was not a mis-read or any error by Mechatrommer

[Electro Fan]

While it's good to learn from the misses, when shooting free throws it's good to end on a made free throw.  So just to show we know a rise time when we see a rise time, here is one that's pretty close to 30 ps.

[Fungus]

if my numbers add up and yours are correct, I think you might have the fastest 1054Z known to mankind.

i think mine is just normal like everybody else rigloled to 100MHz

Turbo Tom did it and got the image below. Original post here

[Mechatrommer]

- just to confirm, this was my (Electro Fan's) error caused by my mis-read on the values displayed, it was not a mis-read or any error by Mechatrommer

retested again with Leo Bodnar Pulser and built-in rT math on CH2 (no cable, direct connection from pulser to inline (diy) terminator to scope. yup confirmed somewhere 1.3-1.8ns (|AX-BX| in manual cursor). so the BW is 200+ MHz. one youtuber confirmed this as well (using -3dB FG amplitude observation) and as Fungus said, many others did too, so i'm normal but when you decrease V/div to 200mV/div (in 1X attenuation setting), relay clicked and boom, 2.6ns and bad risetime (3rd pic) about similar looking to your 2072 picture @ 10mV/div

[Fungus]

when you decrease V/div to 200mV/div (in 1X attenuation setting), relay clicked and boom, 2.6ns and bad risetime (3rd pic) about similar looking to your 2072 picture @ 10mV/div

1x probes have more capacitance.