In this article I'll compare three popular Arbitrary Function Generators. They are all about the same price point and popular among makers.
G'Day, welcome back to the Lab. Today we're going to be comparing some function generators, so I've pulled the, some equipment off the bench behind me and brought it onto the bench in front because today we're looking at the Rigol DG1022 that you would usually see on the bench behind me and we're going to be comparing it with the new Sigilent DG1032x I was originally looking at a third function generator but decided to drop it because the 1032X is essentially its replacement, so let's take a closer look at these two generators.
All right looking down at the front panels we have the Rigol on the bottom and the Siglent on the top both have a pretty similar look and feel the Siglent definitely has a much larger screen but we'll just see how the usability goes so first up I'll just power them both on at the same time so we can compare the turn on time I think the Siglent might be a little more of a little more complex so it might take a little longer to turn on yeah so we can see the Rigol straight away bang up onto the 30 kilohertz sine wave in only a couple of seconds and the siglent is lagging quite far behind. So I think that was maybe two or three times as long turn on time if that matters to you, then there you have it. Straight away we can see the frequency parameter on the Rigol is really, really accessible at a glance, however, that is the only Parameter that you can see just glancing at the screen if you want to take a look at the amplitude, for instance, you do have to interact with the screen. So if you if you accidentally set, offset to something like a volt and then you kind of forget about that and you start messing around with other parameters you kind of have to either realize that you've made a mistake and left some parameter set that you don't want that that might be you know you're working on your scope and you see oh that's a bit funny you have to kind of go back through and look through the parameters to find, oh okay I've accidentally left that at one volt offset, I have to bring that down. On the Siglent though we have the same we have the same kind of wave shape window there just showing us what way we're generating but all the major parameters are accessible just at a glance, so I'll be, while they are smaller you do get all the wave parameters just at a glance, and that's quite nice.
So let's do a road test and see how easy it is to set these generators to what we want I've currently got them both set up and a 1 kilohertz square wave at 5 volt peak-to-peak let's just take an easy, let's go with 1 megahertz sine wave one volt peak to peak so we're going to set those three parameters; the wave shape, the frequency, and the amplitude. So over on the Rigol, we have a dedicated button for each wave shape, that's really that's convenient if you want to just change the wave shape without changing any other parameters, so we've got one button press to go to sine wave, then we can enter in one and megahertz for the frequency and then we have to tab over to amplitude and bring that down to one volt peak to peak. So that was pretty straightforward it's nice with that dedicated button although you again like I said you now have completely lost sight of the other parameters so you kind of have to procedurally set them rather than just at a glance they aren't made a mistake there I need to fix that.
Over on the Sigilent we have to we have to actually bring up the waveforms menu to change the way shape so to press waveforms and then bring it over to sign and then we can enter around one Megahertz and you can see we're still on 5 volt peak-to-peak i have to jump down to amplitude and enter One Volt Peak to Peak, so the user experience is pretty similar both of those. I like that the Rigol has the dedicated wave shape buttons but then again you do have to tab around to see or read back what those parameter values are.
Okay now that we've got a kind of reference when it's dialed into each generator let's have a look at what there's this operational envelope - each one is I mean we d of know the base headline spec those are in a table in the article let's actually have a look at what kind of frequency and amplitude each can deliver across its range because that's that's really the more important feature. So remember I'm a sine wave 1 megahertz and 1 volt peak-to-peak so a 1 megahertz sine wave let's see yet I'm still on one meg, let's see what the maximum amplitude the Rigol can deliver is and I'll just wind that up with the jog wheel all right so we can reach our full 20 volt peak-to-peak on the sine wave at a megahertz so now that we are at that constraint how about we jump over onto frequency and just see how that goes now that we're at 20 volts peak-to-peak as I wind this up, ok so we can maintain 20 volt peak-to-peak all the way up to 20 megahertz that's pretty decent I'll bring this down I reckon maybe if we go down to 10 volt peak-to-peak we can bring the, actually no we've hit a 20 megahertz constraint so in fact that's 20 volt peak-to-peak has been sustained all the way into 20 mega Hertz that's that's really not half bad I don't suppose we'll be able to get much, if any, offset yeah okay so so to reach 20, 20 megahertz and 20 volt peak to peak we, we can't really have any Headroom left for any voltage offset on that waveform. I wonder, I wonder if we brought that down to 10 volts peak-to-peak, what our off set can do okay yeah we can get a 5 volt DC offset and that's that kind of a kind of makes sense.
Okay now it's the Siglent's turn, I don't suppose that will have any trouble getting to its full 30 megahertz on just one volt peak-to-peak so let's jump over on to amplitude, so I'm at 30 megahertz and let's wind that up and see how high we can go okay, so we're only able to get to 10 volts peak to peak but we are at 30 megahertz, remember that the Rigol would only go to 20 megahertz so just to make the test a bit fairer I'll bring this down to 20 megahertz and we'll see what we can do at the amplitude there. Okay so it looks like for the Siglent, we can only achieve 10 volt peak to peak at 20 megahertz remember the Rigol was able to get to 20 volts peak to peak at 20 Meg, so it looks like we have a bit of a frequency and amplitude trade-off there the Rigol can only go to 20 megahertz but it can apparently deliver 20 volts peak-to-peak at that frequency whereas the Siglent can go all the way to 30 megahertz but from 20 it can only bring that 10 volt peak to peak.
All right I've got the Scope out and turned off the light so you can see the screen properly I have the generators off camera just so we can make the most of the screen here what we're going to do now is a bit of a bit of a signal generator killer test we're going to generate generate square wave at the maximum amplitude we can just whine the frequency up to see what the shape of that wave looks like I'm going to use the same lead for both scopes well for both our generator sorry so that we don't have any you know any inconsistencies in the lead.
So at the moment I have a I'm testing the Rigol, so I have a hundred kilohertz square wave and I'm at the full 20 volt peak-to-peak so I'm just going to start winding that frequency up and we'll, we'll keep an eye on the shape of that wave. At the moment it's looking pretty good we're at we're at 500 kilohertz and that's still like a nice, a nice hard edge I'll make sure that trigger is in the center let's bring up to a megahertz and we still we still have a nice, nice clean edge. What's going on with this is triggering, I have an offset okay still still a nice edge it one megahertz, I'll bring it up and bring it up we can see the the rise time isn't really changing of course because it's trying to drive just a pure square wave so we're really interested to see how far can maintain that nice edge. Okay we can see things getting getting a bit furry and of course I know it still looks fine out here we still we still have a good edge compared to the rest of the wave but it's starting to come undone we're at five megahertz and that's where we've maxed down so five megahertz is the upper limit that we can drive a 20 volt peak-to-peak wave and if I bring that all the way down I'm going to bring that down to something sensible like to like four volt peak-to-peak so I always have to remember that I've brought down to 4 volt peak-to-peak and we'll see if we can wind the frequency up but it looks like five megahertz is the highest frequency square wave you can generate of course no offset, low amplitude, even if I bring that down to something crazy, something like you know still well it's not really really small one volt peak-to-peak and I still I still kind of get any higher on that square wave so let's look at the shape I'll bring the amplitude up little bit more I'll bring it up back up to 4 volt peak-to-peak probably a little bit a little bit more you know meaty and we'll look at that edge. And yeah, like, you know there's definitely no overshoot there's not really there's not really any overshoot or ringing or anything like that but we've kind of we've kind of lost the square edge that we're looking for what's the rise time on this the rise time is the average at the moment others I mean the average in the current at the same so we're looking at about 20-23 nanosecond rise time for the Rigol let's see how the Siglent compares.
So I'll just move that probe, I'll just move that BNC lead off the Rigol and onto the Siglent and we'll see what it's doing. So where did we start I think we started down at 100 kilohertz I mean if you can't do a Square wave at 100 kilohertz then you know, almost, what's the point really about we'll start off at the same point so we can see how that way it develops over time. The amplitude 20 okay I can reach 20 volt peak-to-peak on the square wave that's good, so it looks like the square wave we can reach a much higher amplitude on I think the I think that the Siglent uses a special square wave generator all right let's let's bring that a little more in to view, Okay so here we are just a recap to the cigarette and I went back at our starting point which I think was 100 kilohertz 20 volt peak-to-peak square wave so let's now wind up the frequency and this is what we're looking like at 500 kilohertz. This is a 200 nano second time division, we can see we've got some we've got some overshoot creeping in but I feel like I feel like this is going to be a much more, a much harder edge than we got on the Rigol okay here we are a megahertz and we're still looking still looking pretty good that's still a nice hard edge the rise time is all the way down at about 11-10-11-12 nanoseconds the average here is showing 11 nanoseconds that's pretty promising that should be held all the way up to the full frequency I suppose but I think the Rigol was in the 20s so the rise time is already about 1/2. Alright so we are up to 3 megahertz now and where did we get to on the Rigol, I think we got to 5 so I look at 5, ok we are at 5 megahertz, 20 volt peak-to-peak and what does the? So this is now this is now the upper limit of where the Rigol could go so let's have a good look at the shape now because this is the, this is essentially where the Rigol dropped off, so the signal. We have a rise time of 10 nanoseconds that's that's pretty good I do wonder what effect this leads having on the signal I wonder if this overshoot or this distortion is an effect of the lead or an effect of the output stage of the generator remember the Rigol had some pretty soft edges so it will be interesting to get a whole bunch of leads and really see what the what the effect of those are I couldn't really comment on the quality of this lead but at least for this test we're taking the same lead so we can kind of remove that from the equation and just compare the quality of each. So here's the trade-off we have a really really fast edge then we have a bit of we still not at the end get there this is where the Rigol dropped off, let's see how far we can hold 20 volt peak to peak on the square wave so we're currently at 5 megahertz and I can bring that up too, Wow ok, so once we once we crossed 10 megahertz were already we're already double now, once we crossed 10 megahertz the amplitude automatically dropped down to 10 volts peak-to-peak so now we should have a voltage peak to peak, you might be able to see that, is currently at 10 volts and this is what the edge looks like still still a pretty good edge for for 10 volts peak-to-peak remember that we're right at the top of that amplitude limit so when you've got a fast edge and you're slewing across 20 or 10 volts there's down to be a little ripple on the end of it. Let's keep going and see how far we can maintain 10 volt peak-to-peak we're currently at 20 megahertz so that's, that is four times the frequency of the Rigol and the edges are starting to soften up a bit that's getting, it's getting yet it's it's still kind of like a Square wave but we're approaching more now the slew rate limit for that amplitude but at least in software we can go all the way up to 30 megahertz 10 volt peak-to-peak without without any limits. Of course the the square wave is now quite distorted I wonder what that will look like at a lower amplitude, I think what do we take the what did we take the rigol down to, was is four volt peak to peak think it was something like that I don't really think that way shape has changed very much so that's quite interesting if we go down to two volt peak-to-peak, yeah that wave shape is quite similar. So yeah it's I mean I'm no metrology expert I wonder, I wonder what effects the lead had on both of these tests whether in the Siglent it's causing some own shooter on the shoot or in the Rigol if it's softening those edges both but one thing is definitely for sure the slew rate or the rise time on the Siglent is a whole lot, it was about half the time of the Rigol, so we can get and I mean we can achieve square waves up to 30 megahertz as opposed to only five on the Rigol.
So not a particularly rigorous test but at least now we have some qualitative information about the operational envelopes of these two generators how, how amplitude derates as frequency increases or vice versa. And it's interesting to see the the qualitatively, the wave shapes of each scope as the frequency is increased. Bearing in mindI am using a not a low quality lead just that I don't know the quality of the lead, so that's just worth bearing in mind that we're we're only looking I guess at the the qualitative difference between those two wave, not the, not the absolute rise and fall times as such.
I'm just going to take a moment to dive through the article for this video because I think it has a few important things that are worth being in the video. Up first we have the the base spec stable this was comparing perspective the three abitrary function generators, the one in the middle the other Siglent one that I dropped from the review so we're only looking at the left side which is the Rigol and the right side which is the Siglent and in each column I've emboldened the, the winnings you know, headline specification for each device so that's that's what that means and the interesting thing to note is that the Siglent has identical channels channel 1 and channel two have the same specifications; often in two channel entry level arbitrary function generators you really have all the the flagship specifications pushed into the first channel and then the second channel is there kind of is a nice to have just with some small signal stuff usually you'd only expect to see about one and a half four or three or even up to five volts on the second channel but on the Siglent at least we have an identical channel 1 and channel 2 so the experiments that we performed on the siglent for that are that square wave generated killer test. That would have performed identically on channel 2 but I think the Rigol might have fallen over.
So I've taken the time to dive through the data sheets for the units you can even find those linked in the article and one thing that I was particularly interested in what the distortion of a sine wave purity so this can be kind of hard to compare between different models because often different frequencies thresholds are given so it's kind of hard to hold in your mind at once is this one better than this one for instance you're dealing with this order you're juggling a lot of numbers in there at the same time so I've just plotted them just to I guess just to show a little more clearly what's going on so we had in the blue line we had our Rigol in the dotted gray line we had be the arbitrary function generator that was dropped the other Siglent, so we had blue Rigol and orange is the Siglent that we're looking at today; and on the Left we have the distortion this is in DBC that's as decimals with respect to some base carrier wave. So here, lower is better that the more negative you can be the better. Across the x-axis we've got just the frequency for the sine wave so we start at one kilohertz and we wind up over 100 megahertz, which of course these can't generate but we're looking at a log scale here it must be important thing so we have one kilohertz 10 100 kilohertz and then we make the jump to 1 megahertz. These lines would technically go all the way probably down this way all the way off to DC but of course you can't show zero on a log scale, so I just capped it at one Kilohertz.
The important takeaway here is that we have the distortion for the Rigol at negative 45 dB which is pretty respectable for a piece on entry level or maker equipment and then as the frequency of the sine way is increased up to a megahertz we get a jump to negative 40 DBC and then we have another jump I think that's what is that that's probably around five megahertz I suppose on the log scale. So we wind up from at best negative 45 DBC and at worst negative 35 DBC pretty respectable.
For the Siglent however we start at negative 60 and go through a single jump at 10 megahertz, up to negative 50 DBC so already the worst performance distortion from the Siglent is still better than the best-case performance from the Rigol at 45 we have we have the entire line for the Siglent sitting below the entire line for the Rigol so that's that's pretty outstanding this this is a really low distortion function generator for its price. Moving on anyway I just quickly documented that sine wave at square wave function generator killer test that we had a look at before so we have a screen grab of both of those wave forms, just in case it didn't show up to one of the video along with the data if you want the actual screen grabs I think also included a download link so you can have a look at those and pour over the data to your heart's content.
Moving past that we come to the software so I won't go through actually driving the software today - it's quite time-consuming but suffice it to say we have in the two camps we have Rigol's Ultra-Wave and we have Siglents Easy Wave and I'm probably going to mix those up at some point in the video so hopefully you can follow along but there are a few advantages and disadvantages to both. One is, so with the Rigol software which is ultra wave you can you get a blank plot and you can pull in you know standard wave on so here I put in a sine wave and then immediately after that I've tacked on a square wave that's pretty cool you know you can you can start off with these with these standard wave then you can carve out what you want. With the Siglents easy wave, when you import a standard wave it fills the entire window so I couldn't at least I couldn't figure out a way to import a Sine wave into just half the window another square way into the other half I could I couldn't figure out how to do that easily. On the flip side however for Rigols ultra-wave that doesn't appear to be any mathematical way to describe waves and what this means is these are function generators and a function is truly a mathematical function, so we should be able to describe that function using a expression, so up here I'm now in single ins easy wave and you can see that I described some mathematical function using Sine and Cos and actually summing them together changing some amplitudes changing changing some frequencies it doesn't just stop there that you can you can do other operations like you can multiply and divide all out good stuff it doesn't look like in a Rigol that you can do anything like that so I suppose for any complicated function you only have a couple of options you can generate some data points so you can open up MATLAB, octave, Wolfram Alpha what have you you can describe you can write down the function you want to generate and then you just have to generate a list of data points that you then can enter or maybe import into Ultra-Wave that or I suppose you could try and hand it at hand drawing it which just seems kind of fraught, I mean if you want to generate an exact way both of these pieces of software allow you to hand draw waves and that just seems to be kind of from our other one coordinate entering which they both have or function entry which only the Siglent software Easy Wave has.
Now of course the software differences because we're talking about software here, and software can be upgraded, that only reflects the state of affairs as it is now in July of 2017, so I would really like to see a software update from Rigol to fix that that function entry option that I think is missing if it is that I couldn't find it and I'd also like to see from Siglent maybe an option to not have base waveforms like sine square fill the entire sample space and maybe only fill a custom amount of that sample spaces so that that way you can you know stack up a few different wave if you really wanted I'm not sure how how useful that feature would be but it seems like it seems like it would be a pretty easy thing to include.So I guess that draws things to a close for this comparison let's just reach out the the comparisons between the two devices I really like the the Large screen on the Siglent, I really liked being able to see all the parameters at once I mean definitely on the Rigol you can see that parameter from a mile away but if you accidentally had, or if you had something set that you forgot about like you had some offset in place and you just forgotten about that you would have to actually dive into the menu to see that, whereas on the Siglent you can see all the necessary parameters and a glance the right goal could definitely push a higher amplitude sine wave up to its maximum frequency but the Siglent it is able to reach higher frequencies overall especially on the square wave where can get it can go all the way up to 30 mega Hertz whereas the Rigol topped out at 5 so you need to do a square generation up to 30 megahertz then this is the only one of the two that will do it. The second channel on the Rigol is a despec'd channel I have that covered in the article, but the Sigilent it has identical channels on channel 1 and 2 so that's that's really important if you want to mix signals as well that's for the software side of things while the software experience is pretty similar for the 2, I really value the ability to enter in an exact mathematical function and have the Siglent generate that as opposed to regular where it seems like the the most complex you can get is entering single data points so maybe you can generate a list of data points and import them but even then that's another step to the workflow, so I think the Siglent wins out on that so I think the clear winner for this comparison is the signaling SDG1032x, better screen better specs, overall just a much more modern device. I think the the Rigol is kind of showing its age and considering that these are almost identically priced units I just think that for the same price this is a much more capable unit. So if you own or have used either of these units and want to chip in, I'd love to hear your thoughts in the comment section for this video or article and absolutely if you think I missed out on anything important then please do comment we'd love to hear feedback I'll catch you next time
So I guess that draws things to a close for this comparison let's just reach out the the comparisons between the two devices I really like the the Large screen on the Siglent, I really liked being able to see all the parameters at once I mean definitely on the Rigol you can see that parameter from a mile away but if you accidentally had, or if you had something set that you forgot about like you had some offset in place and you just forgotten about that you would have to actually dive into the menu to see that, whereas on the Siglent you can see all the necessary parameters and a glance the right goal could definitely push a higher amplitude sine wave up to its maximum frequency but the Siglent it is able to reach higher frequencies overall especially on the square wave where can get it can go all the way up to 30 mega Hertz whereas the Rigol topped out at 5 so you need to do a square generation up to 30 megahertz then this is the only one of the two that will do it. The second channel on the Rigol is a despec'd channel I have that covered in the article, but the Sigilent it has identical channels on channel 1 and 2 so that's that's really important if you want to mix signals as well that's for the software side of things while the software experience is pretty similar for the 2, I really value the ability to enter in an exact mathematical function and have the Siglent generate that as opposed to regular where it seems like the the most complex you can get is entering single data points so maybe you can generate a list of data points and import them but even then that's another step to the workflow, so I think the Siglent wins out on that so I think the clear winner for this comparison is the signaling SDG1032x, better screen better specs, overall just a much more modern device. I think the the Rigol is kind of showing its age and considering that these are almost identically priced units I just think that for the same price this is a much more capable unit. So if you own or have used either of these units and want to chip in, I'd love to hear your thoughts in the comment section for this video or article and absolutely if you think I missed out on anything important then please do comment we'd love to hear feedback I'll catch you next time