Picking an Arbitrary Waveform Generator: Keysight 33120A vs TTi TGA1244 vs ? - Page 1
Forum section: electronics / testgear

author: dkozel
author_rank: Regular Contributor
timestamp: March 19, 2015, 10:18:03 pm
content: Hello folks,I'm looking to add an AWG to my bench (already set with misc multimeters, PSUs, oscilloscope, logic analyzer, digital pattern generator, spectrum analyzers, and software defined radios, etc). I do mainly embedded device development and RF work both as a hobby and professionally. I've started learning and playing with more analog circuits and amplifier design so a waveform generator is a pretty necessary next tool. What I don't know is what I really need/want for a first AWG.I'm hoping some of you will have thoughts and opinions you'd be willing to share.Near me there are an Agilent 33120A and a TTi TGA1244 available for $550. Both are 40MS/s 12 bit AWGs. The big differences that I see are four outputs and 64k patterns for the TTi (and several patterns can be concatenated) to 1 output and 16k patterns for the Agilent. The Agilent is smaller though. Thoughts? I'd probably go for a Siglent SDG1025 or SDG5082 which have 125MS/s and 500MS/s respectively and more modulation options otherwise, but don't know if I'm better off with something else! The Hantek HDG2002B thread here is intriguing, but I wasn't able to figure out if phase locking the channels was possible.My thoughts more readable:* How important is samples per second? The SDG5082 and Rigol AWGs have literally over 10x the samples for not 10x the rated sine bandwidth.* Thoughts on multiple channels? I think 2 channels would be useful for experimenting with opamp circuits and supplying quadrature signals to RF circuits.* What am I not thinking about? There are always things that get missed in the decision making, can you think of some that would be worth considering?Tempted by the multiple outputs and quality of the TTi. My budget is about $600 and I'm located in the UK.Any useful feedback or comments? Many thanks!

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: March 19, 2015, 10:49:28 pm
content: Have you looked at the Rigol DG4062?

author: alterbaron
author_rank: Contributor
timestamp: March 19, 2015, 11:16:06 pm
content: If you're going to get an AWG, get one with (at least) two channels. It'll be a much more versatile instrument than a 1 channel wavegen. Two channels will be especially useful for testing circuits like mixers and phase comparators. It also comes in handy for miscellaneous things as well.Examples:Feed an arbitrary waveform that represents a bit pattern into the modulation input to generate a modulated signal with the data you want.Use the second channel to generate an external trigger for your scope that's related in phase to the signal from the other channel.Run a frequency sweep from one channel and generate a sawtooth wave with the same period as the sweep from the other channel. Use the oscilloscope x-y mode to get a plot of the frequency response of your DUT.I went with the Siglent SDG1025, and am happy with it so far. If you have any questions about it, feel free to ask!

author: joeqsmith
author_rank: Super Contributor
timestamp: March 20, 2015, 02:16:25 am
content: No idea what your requirements are.I bought a new HP33120A the year it came out. It gets a lot of use and has never had a problem. Software interface is simple. I have been very happy with it.Also have an old Sony AWG2041. Again, simple software interface and has been very reliable.My first general purpose ARB was home made. Have also made three other ARBs. These have been for specific projects.This video shows the last one I built that is used to simulate an engine.

author: skipjackrc4
author_rank: Regular Contributor
timestamp: March 20, 2015, 02:31:08 am
content: I have a Siglent SDG5082 that I really like. Almost all my equipment is HP/Agilent, but the specs of the affordable HP arbs were so much worse than the Siglent I couldn't justify paying for what was essentially just the HP name.

author: tautech
author_rank: Super Contributor
timestamp: March 20, 2015, 02:46:41 am
content: Quote from: dkozel on March 19, 2015, 10:18:03 pmBoth these models are quite mature, trouble free and have a large following on EEVblog.Firmware has recently reached the stage where the list of bugs and features that need improving is very low.Even a dedicated thread to the 800 & 1000 series that you have probably seen already.https://www.eevblog.com/forum/testgear/the-sdg1000-and-sdg800-thread/Memberjobogrecently won a SDG1025 AWG, you can see his first impressions in this post:https://www.eevblog.com/forum/testgear/win-a-free-siglent-oscilloscope-or-generator!/msg631058/#msg631058

author: markone
author_rank: Frequent Contributor
timestamp: March 20, 2015, 12:39:34 pm
content: Quote from: dkozel on March 19, 2015, 10:18:03 pmIf you really need a signal generator on the top of your bench, my suggestion is to move toward something else, a decent device for the money like Rigol DG10xxZ or Siglent SDG50xx.Probably you have not fully read the related threads, a lot of HDG's features are broken or missing and the firmware is highly unstable with no update from manufacturer.Yes, it's cheap and specs are interesting (16Bit -250 MS/s DAC, 64MB buffer), but that's all.I got one months ago when the "Firmware Reverse Engineering" thread was active and promising, but everything stalled, probably the effort required to make a minimal open source firmware version is way too high for people spare time job.It's an expensive toy and if you need it for a serious work, you risk to trash 300 Euros, plus your time.Just my 2 cents.

author: dom0
author_rank: Super Contributor
timestamp: March 20, 2015, 01:37:37 pm
content: ... AWGs are somewhat overrated ...you sure you need one if you don't know how fast it should go or how many channels you want?

author: idpromnut
author_rank: Unknown
timestamp: March 20, 2015, 02:49:26 pm
content: Quote from: dkozel on March 19, 2015, 10:18:03 pmThe answer to this is yes it can phase-lock both channels, but I would take markone's advice and go with another brand of function generator, as the HDG models are of poor firmware quality (yes, I have one, and yes, I confirm both of these statements).

author: dkozel
author_rank: Regular Contributor
timestamp: March 20, 2015, 04:19:50 pm
content: Hello Mike. I have a friend with the DG4062 and it looks great. Its over 200 gbp more than I'd like to pay though.Alterbaron, I agree with the multiple channel arguments. I'd say that's me striking the 33120A off as a first AWG. The SDG1025 does seem to be the common choice and is considerably cheaper than the Keysight or TTi instruments.joeqsmith, Not knowing my requirements is quite the issue. I can only make vauge guesses myself beyond being able to say that two sync'd outputs is certain to be useful for testing and working on analog circuits with multiple inputs. The modulation point made by Alterbaron is also a good one that I hadn't fully thought of. I had thought of the usefulness of being able to sum a noise channel with another channel. I believe the Siglents can do that.skipjackrc4, Did you consider the SDG1025? What made you go with the 5082?tautech, I have seen that thread. I'll go over them more in detail now.markone, I have read through the thread and do know about the issues. That's why the siglent was higher up on my list. The fact that lots of work was happening on it was what pulled me in, as well as the price of course. I hadn't realized that the firmware work has slowed though. These are exactly the type of comments I was hoping to get from this thread. Thanks to you and idpromnut for the feedback on the HDGs.dom0, I've started working with opamp circuits and have been using the DAC on an ARM as a crude generator, but its inconvenient and the low amplitude is less than useful. Yes I could add an amplifier and buffer to it, but at some point its worth it to me to have a purpose built tool around. As for channels its true I hadn't fully thought it out, and likely still haven't as I can't tell you what I'd even do with four channels rather than two, but I can name several uses for two rather than one. The answer is certainly to get something decent but lower cost to start off with.I think I can put the saved money to better use than assuaging brand name hunting. Thanks all.

author: Lightages
author_rank: Unknown
timestamp: March 20, 2015, 04:25:40 pm
content: If you do go for the SDG1025 keep in mind that there is horrible jitter on the square wave output. This can be worked around, mostly, by using the pulse waveform output and choosing 50% duty cycle.I have an SDG1025 and I am happy with it for an all round function generator. I haven't used the AWG part at all yet so I have nothing to comment on that yet.

author: rdl
author_rank: Super Contributor
timestamp: March 20, 2015, 04:57:41 pm
content: Do the Siglents still come with factory installed rust? There is a post in the EEVBlog #497 thread made this year that seems to indicate they do.

author: Lightages
author_rank: Unknown
timestamp: March 20, 2015, 06:14:51 pm
content: I didn't see any in mine.

author: dom0
author_rank: Super Contributor
timestamp: March 20, 2015, 06:22:09 pm
content: Quote from: dkozel on March 20, 2015, 04:19:50 pmMaybe go for a traditional function generator? While sometimes convenient there is seldom a need/requirement for an AWG.

author: Lightages
author_rank: Unknown
timestamp: March 20, 2015, 06:32:24 pm
content: Although the SDG1025 is a bit more money, it is a very very good function generator even for the money. The fact that it has AWG is a bonus.If you need an AWG it is there and if you need one.

author: markone
author_rank: Frequent Contributor
timestamp: March 20, 2015, 11:20:13 pm
content: Quote from: rdl on March 20, 2015, 04:57:41 pmHDG2002B too comes with factory installed rust

author: markone
author_rank: Frequent Contributor
timestamp: March 20, 2015, 11:40:22 pm
content: Quote from: dkozel on March 20, 2015, 04:19:50 pmThe DG4062 seems like an overkill if you mainly work with OpAmp, a DG1032Z would be way enough and should be in your budget range.

author: tautech
author_rank: Super Contributor
timestamp: March 20, 2015, 11:57:31 pm
content: Quote from: dkozel on March 19, 2015, 10:18:03 pmA further thought for you.....The SDG1000 series have JUST been made BW upgradeable in their latest firmware,Seehttps://www.eevblog.com/forum/testgear/siglent-technical-support-join-in-eevblog/msg628011/#msg628011and following posts. Confirmed by Siglent.So you could get the model you think might do all you want and upgrade if needed later.This could save you quite a few bucks initially and you might find it does all you want anyway.Still it's nice to know you can up-spec later if needed.The ONLY thing that is not clear yet is some higher BW SDG1000 models do have a fan, maybe without one the BW upgrade will be limited to "with OR without fan" models.This needs to be clarified with Siglent next week.

author: drakke
author_rank: Regular Contributor
timestamp: March 21, 2015, 12:38:18 am
content: Quote from: Lightages on March 20, 2015, 04:25:40 pmI have a SDG1025 also.Can you post a picture?Any more information on this?

author: rf-loop
author_rank: Super Contributor
timestamp: March 21, 2015, 01:56:30 pm
content: Quote from: Lightages on March 20, 2015, 04:25:40 pmHere some images about normal SDG1000 series generator. (in this example SDG1010)Two images about Square wave. Old times there was high amount of glitches just before rising edge (ans also same before falling edge. (just there in corner) Glitches level was up to 50% of signal level and also theey start far before rising edge.Corner zoomed 100x (note signal level)Corner zoomed 1000xThen about Square wave cycle time jitter.It is well inside specifications (spec: typical 0.1% at 1kHz) Here max peak time error is around 0.05%. It need also note that many manufacturers do not tell anything about peak values. Mostly they tell RMS jitter. It also depends what is distribution of samples for calculation. I can not even imagine what is here true rms value of jitter. Horizontal scale is zoomed 1000X related to delay time (cycle time)This is well inside specifications. I do not know what is horrible (what is definition for horrible?). Some times 1ns jitter is horrible and some times 1ms jitter is still ok. What other this price class function generator give better? Then, if use pulse mode for square wave (why not use) for example 1Hz frequency. Cycle time is 1s. Working principle jitter is 8ns and then some small jitter from reference clock etc. If we think it is total 10ns. 1us is 1ppm in this case. 10ns is 0.01ppm.With Square function is is perhaps 0.1%. 1s cycle time it means 1ms (1000ppm)1MHz cycle time is 1us. 0.1% is then 1ns! But with 1MHz Pulse mode still have 8ns jitter.Here Pulse mode risetime. Well under 7ns. Also overshoot is well inside sppecifications.Pulse mode do not have at all these rising start and falling start edge noise. Pulses are generated totally different working principle than Square. Only Square is derived from internal sinewave using classic comparator method what have some advantages but also disadvantages.Using Pulse mode instead of Squere give less cycle to cycle time jitter with low frequencies. In some frequency point when going higher freq it turns opposite and Square give less time jitter. This is natural and normal when look circuits working principles.Square wave is derived from internal sinewave using PECL comparators. Pulse is done different, directly using DAC's. For adjust frequency (inside some time interval) correct it need 8ns "hopping" in cycle to cycle and in pulse width.) Square wave derived from internal sinewave do not need this, but with low frequencies comparator method make jitter due to fact that internal sinewave is not ideal pure with zero noise and also comparator is not ideal component.Here one example from very old test about pulse mode 8ns hopping.Picture 11.Pulse mode. Frequency 117.72Hz pulses are around over 8us wide.Trigger position one pulse before centerline positioned pulse.Center line zoomed (small picture inside) and zoomed more up to 2ns/divNow here we can see that pulse mode jitter is bistable. (it do 8ns jumping forward and back for adjust freq. This is nessessary in this kind of "simple circuit working principle" and 125MSa/s)Both channels jitter is 8ns (8ns jump in place or not jump. Both channels do this)