EEVblog #892 - Siglent SSA3021X Spectrum Analyser Teardown - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: June 22, 2016, 11:19:41 am
content: A very detailed look inside the new Siglent SSA3021X 3.2GHz Spectrum Analyser.The entire RF section is broken down and analysed in depth with a block diagram overlay.

author: jancumps
author_rank: Unknown
timestamp: June 22, 2016, 11:25:18 am
content: You may also have broken down youtube. There are playback errors.The error is very representative for a teardown video error thoug.

author: Pinkus
author_rank: Frequent Contributor
timestamp: June 22, 2016, 01:41:06 pm
content: Very nice. Thank you.May I ask for some high-res photos also from TG and main processor board?Interesting to see on the upper right sight: an SD card connector and an unpopulated FPC connector with a missing TSSPO chip. My guess: the latter could be for a planned and/or optional (though resistive) touch panel cable with touch screen controller?Thx

author: EEVblog
author_rank: Unknown
timestamp: June 22, 2016, 01:47:23 pm
content: Quote from: Pinkus on June 22, 2016, 01:41:06 pmYes, will upload tomorrow.

author: System Error Message
author_rank: Frequent Contributor
timestamp: June 22, 2016, 04:02:26 pm
content: Would really like to see this in action, do you think you could do a video of it?edit: nevermind just found it in a comparison video. Its just unboxing and teardown videos without any action have become too common.

author: retrolefty
author_rank: Super Contributor
timestamp: June 22, 2016, 04:12:56 pm
content: The teardown was great. Sure seems like a whole lot of SA for the price point. I don't need a SA but I've always dreamed of owning one.

author: Laertes
author_rank: Regular Contributor
timestamp: June 22, 2016, 05:10:35 pm
content: I gotta say, the format you chose for this teardown is great! It seems you took a bit of a page from Shahriars/The Signal Paths book there, with the block diagrams and the photos with overlay, each individual block explained in depth etc.Excellent workThough I do imagine it's a lot more work than just dicking around with your pointer straight on the actual board...

author: tautech
author_rank: Super Contributor
timestamp: June 22, 2016, 08:26:21 pm
content: Quote from: System Error Message on June 22, 2016, 04:02:26 pmRelevant threads:https://www.eevblog.com/forum/blog/eevblog-891-siglent-ssa3021x-vs-rigol-dsa815-spectrum-analyser/https://www.eevblog.com/forum/testgear/comparison-rigol-dsa815-tg-with-siglent-ssa3021x-spectrum-analyzer/https://www.eevblog.com/forum/testgear/siglent-ssa3000x-spectrum-analyzers/https://www.eevblog.com/forum/testgear/hack-of-sigllent-spectrum-analyzer-ssa3021x/Manufacturers website:http://www.siglent.com/ENs/pdxx.aspx?id=1299&T=2&tid=18

author: G0HZU
author_rank: Super Contributor
timestamp: June 22, 2016, 08:49:41 pm
content: At 23:32 in the video the function of the first RF switch U1 is to switch in the overload dummy load R1 (via C9) if there is an overload.i.e. if there is a large overload the analyser can simply divert the RF input to the big 49.9R resistor R1.The input blocking cap C10 is likely to be a big value possibly as big as 1uF. This can obviously store a lot of energy (for a given charge voltage) compared to a regular RF cap down in the nF range so I would expect to see something to protect the front end from transients from this cap if DC is ever applied/removed at the analyser input. Maybe those clamping diodes help here but it's hard to see how they are configured.

author: G0HZU
author_rank: Super Contributor
timestamp: June 22, 2016, 08:56:12 pm
content: The second SOT23-6 RF switch U2 at 24:06 looks like it allows an internal test signal to be switched in to the front end of the analyser. Possibly for self testing/calibration purposes. The opamp IC to the right of it is probably something to do with the RF overload detection. Possibly a crude diode detector/comparator/trip to control that first RF switch U1 that switches in the (overload) dummy load resistor R1.The input switches U1 and U2 look quite feeble in the SOT23-6 package but they are probably rated to about 1W and probably a bit more before they actually get damaged. So U1 can probably dump something in the ballpark of 1W into R1 if there is a bad overload. But much more than this and something is going to release some magic smoke somewhere...

author: altaic
author_rank: Unknown
timestamp: June 22, 2016, 09:09:07 pm
content: Dave, I really liked the front-end breakdown and explanation of the block diagram!As people mentioned in the thread for the previous video, it'd be great to have a fundamentals friday explaining how SAs work and what each stage of the front-end does to the input signal to do the business. Actually, a video series on analog front-ends in general would be awesome-- you've already done one on multimeters; 'scopes and SAs to come?

author: AF6LJ
author_rank: Unknown
timestamp: June 22, 2016, 09:17:49 pm
content: By the way Dave;The common way to pick off signals for sampling is to use a directional coupler.Their PCB implimentation of a directional coupler is tried and true. They look like 10DB couplers. IF I had to put a number on it.Good job on the teardown.One of your very best RF teardowns yet...

author: Someone
author_rank: Super Contributor
timestamp: June 22, 2016, 11:38:11 pm
content: Daylight = 500THzTerahertz

author: AF6LJ
author_rank: Unknown
timestamp: June 23, 2016, 12:21:55 am
content: Quote from: Someone on June 22, 2016, 11:38:11 pmYup

author: tszaboo
author_rank: Super Contributor
timestamp: June 23, 2016, 03:29:52 pm
content: I really liked the added effort for this RF equipment. It was too often: "Look RF voodoo and strange looking antennas!". OK, not really, but almost. This was very good.

author: bitseeker
author_rank: Super Contributor
timestamp: June 23, 2016, 07:00:39 pm
content: Best teardown, Dave. The extra time investment clearly shows and the level of detail is appreciated.

author: richnormand
author_rank: Unknown
timestamp: June 23, 2016, 07:15:32 pm
content: Really appreciated this tear-down and analysis with the diagrams and the board walkthrough of the various stages.Cheers and thanks Dave.PS: considering the comments on the last video comparing the two SP and the fact you did not have it for long I wonder what are the reactions from Siglent on the level of design detail given as well as just opening it?

author: tautech
author_rank: Super Contributor
timestamp: June 23, 2016, 08:17:10 pm
content: Quote from: richnormand on June 23, 2016, 07:15:32 pmDave has a reputation for teardowns so any manufacturer shouldn't be at all surprised that he did.Don't want a teardown and exposure of your design to the world ..... then don't send it to Dave, simple.

author: nctnico
author_rank: Super Contributor
timestamp: June 23, 2016, 09:39:32 pm
content: From what I have seen from the teardown there is nothing Siglent should be ashamed off. However the hardware engineers at Siglent should go after their co-workers in the software department with pitch forks more often to make them do a good job as well

author: richnormand
author_rank: Unknown
timestamp: June 24, 2016, 12:10:13 am
content: Quote from: nctnico on June 23, 2016, 09:39:32 pmFully agree. At this price point this is excellent work.

author: EEVblog
author_rank: Unknown
timestamp: June 24, 2016, 12:28:40 am
content: Quote from: richnormand on June 23, 2016, 07:15:32 pmI just got an email from Siglent, they loved the teardown.

author: bitseeker
author_rank: Super Contributor
timestamp: June 24, 2016, 12:30:52 am
content: That excellent, Dave. Now, how can we use that knowledge to work for us?

author: AF6LJ
author_rank: Unknown
timestamp: June 24, 2016, 12:36:56 am
content: Quote from: EEVblog on June 24, 2016, 12:28:40 amGood Deal

author: coppice
author_rank: Super Contributor
timestamp: June 24, 2016, 02:37:27 am
content: Quote from: EEVblog on June 24, 2016, 12:28:40 amThey might have liked it less if you'd done a parallel teardown of the 3.2GHz model, and found the hardware was identical.

author: tautech
author_rank: Super Contributor
timestamp: June 24, 2016, 03:25:23 am
content: Quote from: coppice on June 24, 2016, 02:37:27 amWe already know it is.

author: coppice
author_rank: Super Contributor
timestamp: June 24, 2016, 05:09:43 am
content: Quote from: tautech on June 24, 2016, 03:25:23 amWhere is the information which confirms this? All I have seen it that the feature packs are enabled by a key.

author: Smokey
author_rank: Super Contributor
timestamp: June 24, 2016, 05:16:53 am
content: Paging Shahriar... Shahriar... Please report to the EEVBlog for comments on RF gear....https://www.eevblog.com/forum/profile/?u=8240I wonder if Dave violated their video blogger to video blogger agreement where Dave won't do RF gear and Shahriar won't take apart stuff people send him in the mail.

author: tautech
author_rank: Super Contributor
timestamp: June 24, 2016, 05:18:29 am
content: Quote from: coppice on June 24, 2016, 05:09:43 amNot officially, but read this thread and make up your own mind:https://www.eevblog.com/forum/testgear/hack-of-sigllent-spectrum-analyzer-ssa3021x/BTW already linked in reply #7

author: EEVblog
author_rank: Unknown
timestamp: June 24, 2016, 05:36:37 am
content: Quote from: Smokey on June 24, 2016, 05:16:53 amThis is only my 3rd spectrum analyser teardown

author: rf-loop
author_rank: Super Contributor
timestamp: June 24, 2016, 06:56:01 am
content: Quote from: coppice on June 24, 2016, 05:09:43 amIs it better to read this EEVblog forum bit more deeply.Independent of this and without deep knowledge how different manufacturers optimise they production and models.If look Dave's photographs from boards it do not need very deep knowledge to know that if make these, example qty 100 and run statistics with several test parameters you find that every single unit is different, more or less. Analg RF world is - fun. (Btw, in images I can not fid signs about laser or other method individually trimmed filters or other things etc...)In finally you may find (I do not say Siglent find) that some units are wise to sell as 1.5G models, some may be ok for 2G and some may be ok for 3G. It depends how we set our parameters limit values. Then configure (digitally) these units to different models. If I'm manufacturer I do this. Also Analog Devices do even with simple chips labelling them to 40MHz or 100MHz.... and so on..

author: nowlan
author_rank: Frequent Contributor
timestamp: June 24, 2016, 07:57:16 am
content: Re: RF sections;All those hititte chips made me wonder if it was a reference design, or outsourced.

author: rf-loop
author_rank: Super Contributor
timestamp: June 24, 2016, 09:05:57 am
content: Quote from: nowlan on June 24, 2016, 07:57:16 amReally? Do you really believe that company like Siglent do not have enough well educated and experienced RF engineers for design this kind of simply front end where is nothing special. Siglent is also ODM so if you want something like this you can buy this design from Siglent.Just simple cheap front end without any kind of special "High-End" or "State of art" level things. Why it need outsource design with high risk. All these kind of things need tightly keep inside house. Also they have experince with they older SA models 1010 and 3030. If development team do yearswork and this is result I do not wonder at all this result, perhaps I hope result is better... but, this is much more than crap, so public "raise the cup and give a round of applause" to Siglent SSA product department development team. In this price result is not bad.

author: classical
author_rank: Regular Contributor
timestamp: June 24, 2016, 09:32:32 am
content: Thank you for this great teardown! The Image with block diagram overlay was really well done and extremely helpful. Threre is a lot of work in it. I do appreciate it.

author: coppice
author_rank: Super Contributor
timestamp: June 24, 2016, 12:32:37 pm
content: Quote from: rf-loop on June 24, 2016, 06:56:01 amSo, what you are trying to say is you have no idea, right? It might be the same hardware. It might not. It almost certainly fairly similar, but maybe they use a higher spec version of some key parts.

author: xrunner
author_rank: Super Contributor
timestamp: June 24, 2016, 01:17:58 pm
content: I'd probably consider it if I hadn't already bought a DSA815-TG last year. Something new and better always comes out, that's the way it goes. But for my hobby uses the DSA-815 is perfectly fine.

author: bitwelder
author_rank: Super Contributor
timestamp: June 24, 2016, 04:35:28 pm
content: This teardown was really good, thesignalpath-goodMy vote: O0 O0 O0 O0 (4 Shariars)

author: nctnico
author_rank: Super Contributor
timestamp: June 24, 2016, 06:47:18 pm
content: Quote from: coppice on June 24, 2016, 12:32:37 pmI don't believe they leave producing the 2 or 3GHz model to chance. With modern production processes you can build every unit to precise specifications. If you have different versions you'll also need different microstrip filters so you'll also need two different board designs. Taking the chance with lower spec components isn't going to cut it either. For example: there are many RF switches on the board. If some of them operate to >3GHz and some not the chance of creating a 3GHz capable SA is nearly 0. Also if demand is greater for the 3GHz model you will be left with a whole bunch of boards which you can't sell. So either all units are the same and work up to 3.x GHz or they have specific designs for the 2.xGHz and 3.xGHz models.

author: albert22
author_rank: Regular Contributor
timestamp: June 24, 2016, 10:19:43 pm
content: VERY good video.Thanks

author: TurboTom
author_rank: Super Contributor
timestamp: June 24, 2016, 11:30:05 pm
content: There are quite a few amazing details about the Siglent SSA3021X and the Rigol DSA815 that they have in common. The design of the RF path right to the first mixer is almost identical (a few components are different but function-wise it's exactly the same). Quite funny is the use of the first mixer "in reverse", i.e. RF is applied at the "IF" output of the mixers (HMC488 in case of the Siglent, probably HMC213 in the Rigol -- the surface is lasered blank here) while the mixing product is taken from the RF input. Since the mixers are passive devices (double-balanced diode bridges), this is possible and permits input frequencies (thoretically) down to DC. Both LO and RF "inputs" of the mixers are transformer-coupled and hence have a lower frequency limit. What makes me wonder though if the existing hardware of the 2.1G siglent spectrum analyzer is really capable of 3.2G is the fact that the mixer's IF range is actually specified to 2.5G only. This may be just a limit imposed by the way Hittite has tested this device but it gives some reason for doubts. The HMC213 that I assume to be used in the DSA815 is specified to 1.5G IF so this matches the operational range of this analyzer.Well, that's just food for thought.Another interesting detail is that Siglent used a one-wire unique ID ROM chip (U48, DS2401) on their application processor. Could it be possible that Siglent got batches of ID ranges that refer to a certain frequency version of the analyzer? Or maybe have odd IDs on 2.1G machines and even on 3.2G or vice versa? Or is it just there to be able to identify every single analyzer in the field and prevent it from being tampered with? I would really like to know if the machine still runs without that chip...I guess the Siglent SA will become a new "hacker's paradise"...Oh - just noticed: In the lower right corner of the control board, next to the buzzer, there's an unpopulated footprint of a four-pin header labled "uart". I guess that's the place too look first... Maybe it's easier to get into that thing than expected!Cheers,Thomas

author: nctnico
author_rank: Super Contributor
timestamp: June 25, 2016, 12:13:02 am
content: Still what makes me wonder is that many Hittite chips used in this SA are declared obsolete.

author: tautech
author_rank: Super Contributor
timestamp: June 25, 2016, 12:51:44 am
content: Quote from: nctnico on June 25, 2016, 12:13:02 amReally? How?As rf-loop has alluded to, development will have taken some years and in that time ANY IC's production status can change for whatever reason. Part obsolescence can even result from a change to ROHS compliance or better spec'ed chip in the same package but who knows.Have you never encountered this (of course you f***ing have) or are you just simply trolling the new Siglent SA threads?

author: Smokey
author_rank: Super Contributor
timestamp: June 25, 2016, 02:25:17 am
content: How long did it take to put this video together. This one was definitely not "off the cuff". Lots of prep it looks like.Did you get some help with this one?

author: tautech
author_rank: Super Contributor
timestamp: June 25, 2016, 04:00:04 am
content: Quote from: Smokey on June 25, 2016, 02:25:17 amDo the maths, this is when Dave first announced he had it:https://www.eevblog.com/forum/testgear/siglent-ssa3000x-spectrum-analyzers/msg962513/#msg962513QuoteIf you study the following posts linked above you'll see some forum members gave advice.

author: PartialDischarge
author_rank: Super Contributor
timestamp: June 25, 2016, 04:46:06 am
content: Quote from: tautech on June 25, 2016, 12:51:44 amI dont think hes trolling but its nctnico and his crusade against rigol and siglent products.

author: EEVblog
author_rank: Unknown
timestamp: June 25, 2016, 05:24:15 am
content: Quote from: Smokey on June 25, 2016, 02:25:17 amThis one took about two days by the time I dicked around with all sorts of little stuff. Started as usual on Tuesday and wanted to release Tuesday, but had to do some family stuff and I also decided to do the new overlay thing during it. Wasn't finished and uploaded until Wed night.Almost all my videos I shoot and edit in a day, so you could say roughly twice as long as a normal teardown."prep" isn't the right word, there was still essentially zero "prep", I pressed record and started yapping. Then I decided I'd try to use the photos I had and do all the teardown commentary during the edit, rather than in-camera mic work as I normally almost always do.So the only "prep" was figuring out the blocks and drawing them all, looking up datasheets etc. Once I had all that it was my usual press record and start yapping technique. There was no script or planning what I was going to say, as with all my videos, so IMO, still "off-the-cuff".QuoteNot really. But I was talking about it on the forum and posted an early 1st guess block overlay before I wet to bed and realised I had a lot of it wrong, as was confirmed by several others. So I took another shot at it the next day going through it more carefully.

author: EEVblog
author_rank: Unknown
timestamp: June 25, 2016, 05:28:58 am
content: Quote from: nctnico on June 24, 2016, 06:47:18 pmYep. I'd bet my bottom dollar all units are fully speced to 3.2GHz.

author: EEVblog
author_rank: Unknown
timestamp: June 25, 2016, 05:32:43 am
content: Quote from: rf-loop on June 24, 2016, 09:05:57 amIt makes we wonder if they have poached a designer or two from one of the biggies?, or maybe even Rigol? As I have heard that Rigol have been losing people...Not that I'm suggesting Siglent couldn't have done this with their existing people, but to me it just seems like it had a bit more RF spit'n'polish then you'd expect from their first shot at a spectrum analyser.

author: tautech
author_rank: Super Contributor
timestamp: June 25, 2016, 05:49:18 am
content: Quote from: EEVblog on June 25, 2016, 05:32:43 amAnd again we remind readers this is not Siglents first "shot" at a spectrum analyser although they haven't had one to offer in their lineup for the last year or two.https://www.eevblog.com/forum/testgear/siglent-ssa3000x-spectrum-analyzers/msg964143/#msg964143

author: Brumby
author_rank: Unknown
timestamp: June 25, 2016, 07:05:30 am
content: Yes, Dave. A good job indeed.I found this to be not only good as a tear-down, but informative as to the nature of the beast and actual implementation of various functional blocks.I know it's extra work, but I think it's something I would like to see more of.

author: rf-loop
author_rank: Super Contributor
timestamp: June 25, 2016, 07:38:13 am
content: Quote from: EEVblog on June 25, 2016, 05:32:43 amWhat "first shot"?SSA1010 andSSA3030are predecessors for SSA3000X

author: EEVblog
author_rank: Unknown
timestamp: June 25, 2016, 08:14:23 am
content: Quote from: rf-loop on June 25, 2016, 07:38:13 amYep, I stand corrected.Did those things ever really sell?The SSA1010 shows zero hits on Youtube.The SSA3030 gets two hits on one channel.Zero hits for reviews anywhere

author: coppice
author_rank: Super Contributor
timestamp: June 25, 2016, 09:03:20 am
content: Quote from: EEVblog on June 25, 2016, 08:14:23 amMaybe they never exported them, but they've been easy to find in China. Seehttps://world.taobao.com/search/search.htm?_ksTS=1466844976484_55&spm=a21bp.7806943.20151106.1&search_type=0&_input_charset=utf-8&navigator=all&json=on&q=SSA1010&cna=L%2Fc7DLx%2FFQcCAXvL8GZogKJ6&callback=__jsonp_cb&abtest=_AB-LR517-LR854-LR895-PR517-PR854-PV895_2462andhttps://world.taobao.com/search/search.htm?_ksTS=1466844934601_41&spm=a21bp.7806943.20151106.1&_input_charset=utf-8&navigator=all&json=on&q=SSA3030&cna=L%2Fc7DLx%2FFQcCAXvL8GZogKJ6&callback=__jsonp_cb&abtest=_AB-LR517-LR854-LR895-PR517-PR854-PV895_2462

author: tautech
author_rank: Super Contributor
timestamp: June 25, 2016, 10:58:13 am
content: Quote from: coppice on June 25, 2016, 09:03:20 amThey did, a 2013 quote I've just looked up had them retailing at over $5k for the SSA3030.Needless to say I supplied my customer with something else as he didn't need 3GHz.

author: rf-loop
author_rank: Super Contributor
timestamp: June 25, 2016, 11:00:43 am
content: Quote from: EEVblog on June 25, 2016, 08:14:23 amThere is whole world also outside of youtube.Also someone selling used SSA3030http://maxanalyzer.com/products.php?product=Siglent-SSA3030-9KHz-to-3-GHz-Spectrum-Analyzer(btw, look this equipment rear panel, RS232, LAN,GPIB, VGA, USB, )eBay have still new ones (and expensive),Also it is good to realize that there is big domestic markets inside mainland China. There is lot of things what no one sell in western markets - some company may think that it is perhaps even wise to stay out from western markets. Western markets do not make all happy. Try find example ZLG oscilloscopes from western markets.Living there do not even need know that there is some periphery world outside China.

author: Garan
author_rank: Newbie
timestamp: October 29, 2016, 08:35:34 am
content: Great job on the teardown Dave! I liked how you overlaid the block diagram on the circuit board photo.A few comments:[7:00] The unloaded IC, U15, to the left of the Spartan 6 FPGA is probably a for second bank of DDR memory that isn't shared with the host processor. The additional memory is to provide data buffering for the DSP operations in the Spartan 6. This would enable a number of high performance features: real-time spectrum analyzer operation, digital modulation signal analysis, etc.[23:17] The input switch U1 switches the RF input to the 50 ohm dummy load when there is an overpower condition. The unloaded diodes D31-D34 could be the detector or they could be limiters with an adjustable threshold. Perhaps these diodes were not loaded because they degraded input IP3 and/or caused a rolloff in the frequency response.The following switch U2 has a trace on pin 1. It is likely for a calibration signal as G0ZHU mentioned. By providing a reference signal, the signal path amplitude drift vs temperature can be compensated to some degree.The preamp used non-reflective SPDT switches to increase isolation and terminate any stray leakage into the thru path, which feeds back into the input of the preamp, causing oscillation.[33:07] Your block diagram and photos provided enough information to deduce the frequency plan without doing any measurements.[44:35] The ADC uses bandpass sampling to sample the IF. The Nyquist criterion requires that the signal bandwidth has to be less than 20 MHz. It doesn't mean the IF frequency has to be less than 20 MHz. With a bandpass filter around the IF signal, aliasing can be used to downconvert the signal in the digital domain.70 MHz is the 3rd IF. Since the ADC samples at 40MSPS, 70 MHz will alias to 10 MHz, which in in the center of the first Nyquist zone.810 MHz is the 2nd IF as you already discovered. This allows determining the 2nd and 3rd LO frequencies:3rd LO = 880 MHz (810 MHz + 70 MHz)2nd LO = 3520 MHz (880 MHz x 4)The 1st IF is thus 4330 MHz. (810 + 3520 MHz)1st LO range at mixer port: 4330 MHz to 6430 MHz (to 7530 MHz for 3.2 GHz model)The 2.1 GHz and 3.2 GHz model share the same RF design as one would not use such a high 1st IF frequency and use a frequency doubler in the 1st LO path if the design were optimized only for 2.1 GHz.[15:47] The TG offset synthesizer IC is a HMC835 (33-4100 MHz) according to the part markings, not a HMC832. It is set to 4.33 GHz, the same frequency as the 1st IF.

author: tautech
author_rank: Super Contributor
timestamp: October 29, 2016, 08:51:15 am
content: Welcome to the forum Garan.Sounds like you've had a good study of them, from personal experience maybe ?

author: Garan
author_rank: Newbie
timestamp: October 29, 2016, 09:42:07 am
content: Quote from: tautech on October 29, 2016, 08:51:15 amWhy, yes....I have lots of experience in spectrum analyzer design and teardowns.