Best 14-Bit Digital Oscilloscope - Page 1
Forum section: electronics / testgear

author: trentender
author_rank: Contributor
timestamp: October 13, 2023, 12:03:12 pm
content: Hi,I am looking for a low cost (<=£1000 max appoximately) 14-bit digital oscilloscope which can accurately measure and trigger on analogue signals (eg. 100KHz sinewave) down to less than 20uV peak-peak so it needs to be a scope with a very low noise level. Just being 14-bit does not mean that a scope can measure below 20uVpp since the broadband noise generated inside the scope might be at a much higher level than 20uVpp. So does anyone out there know of any great,low cost ,low noise 14 bit digital oscilloscopes which might fit the bill?Cheers,Ian

author: UK
author_rank: Regular Contributor
timestamp: October 13, 2023, 12:35:40 pm
content: You didn't mention a preferable form factor if it matters.

author: Sighound36
author_rank: Frequent Contributor
timestamp: October 13, 2023, 12:44:32 pm
content: Would suggest either of these two dependingon your channel count required.https://www.picotech.com/oscilloscope/4444/picoscope-4444-overview?lvhttps://www.picotech.com/oscilloscope/4262/picoscope-4262-overview

author: huababua
author_rank: Contributor
timestamp: October 13, 2023, 12:45:14 pm
content: I mean for < 1000 bucks you cant expect a scope with screen.I am using the TiePie Scope exactly for the noise reason.https://www.tiepie.com/en/usb-oscilloscope/handyscope-hs6Within your budget, Scope is okay, SW runs only on windows but API available.Pico also offers a USB Scope with 16 bit resolution - little bit more expensive.

author: trentender
author_rank: Contributor
timestamp: October 13, 2023, 01:20:03 pm
content: form factor of the scope not a problem but looking to buy a new scope not second hand

author: trentender
author_rank: Contributor
timestamp: October 13, 2023, 01:28:12 pm
content: does'nt look too bad,resolution looks like 90uV for the 16 bit scope which is a bit more expensive than I am looking for and a bit noisier than I am looking for but its a lot better than anything I have seen so far so thanks.

author: Sighound36
author_rank: Frequent Contributor
timestamp: October 13, 2023, 01:30:10 pm
content: All of these scopes suggested are new cost.I have a couple of these and are ideal for what you are sggesting the use is, I have more advanced models, but still use these regularly, the Tiepie is a good alternative option as well.https://www.picotech.com/oscilloscope/4262/picoscope-4262-overview

author: trentender
author_rank: Contributor
timestamp: October 13, 2023, 01:31:25 pm
content: I should also have said at the beginning need the -3db bandwidth of the scope to be 100MHz minimum but targetting 200MHz

author: trentender
author_rank: Contributor
timestamp: October 13, 2023, 01:36:20 pm
content: Looking for something like the OWON XDS3204AE which has a resolution of less than 20uV but unfortunately the background noise is sitting at about 350uV so all that lovely potential sensitivity of the 14-bit ADC is thrown away by poor general design of the scope.

author: trentender
author_rank: Contributor
timestamp: October 13, 2023, 01:39:05 pm
content: good performance from this scope but its a very low frequency scope (5MHz).

author: coppice
author_rank: Super Contributor
timestamp: October 13, 2023, 01:44:21 pm
content: Quote from: trentender on October 13, 2023, 01:39:05 pmHigh bandwidth. High resolution. Choose one.

author: trentender
author_rank: Contributor
timestamp: October 13, 2023, 02:14:26 pm
content: Need both wideband (100MHz minimum) and low noise sensitivity (20uV) and lowish cost.Not asking much I know!!!!!!

author: KungFuJosh
author_rank: Super Contributor
timestamp: October 13, 2023, 03:16:15 pm
content: Quote from: trentender on October 13, 2023, 02:14:26 pmYou remind me of this meme, but apply it to your scope requirements:What you really want is significantly more expensive than your budget, so you need to decide which 2 out of 3 (fast, cheap, great) you can live with.

author: Performa01
author_rank: Super Contributor
timestamp: October 13, 2023, 05:19:23 pm
content: Quote from: trentender on October 13, 2023, 02:14:26 pmWe are used to that.When talking about signals below about 1 mVpp, one of the very few options would be the Picoscope 4262, as has been already mentioned. It is only 5 MHz, but it is 16 bits and has a noise level of <5 µVrms (~81 µVpp). You seem to expect noise levels below 20 µVpp and for this I wish you luck. Of course, the noise can be lowered even further, by resolution enhancement up to 20 bits and digital channel filters, but all these measures reduce the bandwidth even further.So, you’re unlikely find any 100, let alone 200 MHz instrument to show 20 µV resolution in the time domain, even if you were willing to spend serious money.On the other hand, even 8 bit scopes, also with much higher bandwidth than just 200 MHz, with adecentFFT, can measure signals that low in the frequency domain. Yet that doesn’t mean they can distinguish 5.00002 mVpp from 5.0 mVpp, if that’s what you want.In other words: the 16000 count DMM with 1 count accuracy and 200 MHz bandwidth of is not going to happen.

author: KungFuJosh
author_rank: Super Contributor
timestamp: October 13, 2023, 06:22:49 pm
content: Quote from: Performa01 on October 13, 2023, 05:19:23 pm*with currently available tech. 😉

author: nctnico
author_rank: Super Contributor
timestamp: October 13, 2023, 06:26:40 pm
content: My recommendation would be to look for something with differential inputs. A pre-amplifier can also be an option to bypass noise in a cheaper oscilloscope front-end.

author: edavid
author_rank: Super Contributor
timestamp: October 13, 2023, 06:47:28 pm
content: Quote from: trentender on October 13, 2023, 02:14:26 pmThis is actually impossible.Referring to a handy noise calculator:https://www.daycounter.com/Calculators/Thermal-Noise-Calculator.phtmlIf you plug in 25C, 50ohms, and 100MHz, you get thermal noise of 9uV RMS (about 60uV P-P).So it's impossible to build a (non-cryogenic) 100MHz oscilloscope with only 20uV P-P (broadband) noise.

author: G0HZU
author_rank: Super Contributor
timestamp: October 13, 2023, 07:54:12 pm
content: If you just want to look at sinewaves then you don't need lots of instantaneous bandwidth.For example, here's a 20uV pkpk signal at 70MHz being fed to my ancient (500MHz BW) 8 bit HP DSO.To be able to measure it and trigger on it, I've used a precision (2 stage) LNA followed by a 70MHz bandpass filter that is about 10MHz wide. I haven't factored in the loss of the BPF so it shows 18uV pkpk instead of 20uV pkpk, but you get the idea...The other plots show the flat gain response of the first stage of the preamp. The input VSWR is very low and the noise figure is less than 3dB.I normally use this precision preamp for noise figure testing, but it can also be used with an oscilloscope to look at tiny RF signals. You can see that the gain response is very flat at 32dB across a huge bandwidth.

author: thm_w
author_rank: Super Contributor
timestamp: October 13, 2023, 10:36:47 pm
content: Quote from: edavid on October 13, 2023, 06:47:28 pm

author: mawyatt
author_rank: Super Contributor
timestamp: October 13, 2023, 10:42:43 pm
content: More like 77K, not 25CBest,

author: edavid
author_rank: Super Contributor
timestamp: October 13, 2023, 10:45:01 pm
content: If that's supposed to be liquid nitrogen, it still doesn't get you there.-196C, 50 ohms, 100MHz -> 5uV RMS -> 30uV P-P

author: nctnico
author_rank: Super Contributor
timestamp: October 13, 2023, 11:30:20 pm
content: You can always parallel channels to even out the noise.

author: David Hess
author_rank: Super Contributor
timestamp: October 14, 2023, 12:47:19 pm
content: Quote from: trentender on October 13, 2023, 01:31:25 pmThat sure is not going to happen. The old Tektronix 7A22 vertical amplifier has 10 microvolt per division sensitivity, but even at a bandwidth of 1 MHz that is questionable. Modern parts can do a little better, but not enough.What could work however is to trigger off of a higher level signal and then use averaging.Quote from: nctnico on October 13, 2023, 11:30:20 pmThe added parallel input capacitance then limits the bandwidth, so a lower source impedance is required.

author: JeremyC
author_rank: Regular Contributor
timestamp: October 14, 2023, 03:04:39 pm
content: Quote from: trentender on October 13, 2023, 12:03:12 pm

author: coromonadalix
author_rank: Super Contributor
timestamp: October 14, 2023, 03:18:03 pm
content: ill wait for an 24bit scope loll

author: coppice
author_rank: Super Contributor
timestamp: October 14, 2023, 03:21:58 pm
content: Quote from: coromonadalix on October 14, 2023, 03:18:03 pmThey effectively exist, in the form of advanced audio analysers.

author: ebastler
author_rank: Super Contributor
timestamp: October 14, 2023, 06:54:22 pm
content: Quote from: coppice on October 14, 2023, 03:21:58 pmBut as explained by edavid, that does not matter. The thermal noise (Johnson noise) is already there. Digitizing it with higher resolution will get you nowhere.

author: coppice
author_rank: Super Contributor
timestamp: October 14, 2023, 07:35:29 pm
content: Quote from: ebastler on October 14, 2023, 06:54:22 pmOf course. There is a reason why we went from typically 100mV 100k ohm audio interfaces in the pure analogue days, to lower impedance 1V CD interfaces, to at least 2V low impedance interfaces in modern 24 bit audio systems.

author: BillyO
author_rank: Super Contributor
timestamp: October 15, 2023, 12:02:35 am
content: Quote from: coromonadalix on October 14, 2023, 03:18:03 pmWith 10nV noise @ 1GHz for $299?Me too.

author: coromonadalix
author_rank: Super Contributor
timestamp: October 15, 2023, 02:01:10 am
content: exactly, even having tons of resolution, if the noise is there, nothing good will come out

author: pdenisowski
author_rank: Super Contributor
timestamp: October 19, 2023, 11:15:32 am
content: Since (surprisingly) no one else hasexplicitlymentioned it yet: you may want to look into ENOB (effective number of bits)But yeah, what everyone else said: the limitation is often the noise, not the number of bits