Experience with Aim TTI TGF4000 series waveform generator? - Page 1
Forum section: electronics / testgear

author: nctnico
author_rank: Super Contributor
timestamp: August 23, 2019, 10:26:09 pm
content: I'm still hunting for a new function generator. I don't need lots of waveform memory but low jitter and stable firmware are important. The TGF4000 series from Aim TTi has caught my eye and I'm contemplating getting one to at least try it out. From the specs it seems it has a clever way of producing waveforms with very fine grained timing. Has anyone any experience with these generators and cares to comment?

author: maxwell3e10
author_rank: Frequent Contributor
timestamp: August 24, 2019, 04:41:27 am
content: Looks intriguing. Could be a competitor to Keysight 33500b series or Rigol DG800/900 series. But arbitrary only has 8192 points and 1.25 ns jitter, so its not a "Trueform". Perhaps for standard waveforms it would be fine. If I were to ask them one question, it is how many time steps per period are used to generate a sine wave.

author: nez
author_rank: Regular Contributor
timestamp: January 08, 2020, 08:49:00 am
content: I have a few questions on the TGF4000 too, forgive me while I struggle to express themI am looking at the specs for the TGF4000 compared to, say, Siglent's SDG2000X series or BK Precion's 4060B series (which seem very similar to each other).ARB Jitter:The various jitter specs for the TGF4000's seem very good in comparison to those other two, except the arbitrary wave jitter characteristic isn't specified the same way. The SDG2000X/4060B's ARB is specfied as "jitter (rms)" = 150ps, while the TGF4000 is "Point to point jitter (typical)" = 2.5ns (1.5ns higher models).The 2.5 (or 1.5ns) just corresponds to the flat sample rate of 400MSa/s (800MSa/s) I assume, but how does this type of jitter look in practice compared to just rms jitter?Square and Pulse waveforms are specified as <30ps "jitter (rms)" for the TGF4000's.Is this difference in ARB jitter spec styles due to the different 'strategies' of the designs? Siglent's datasheet describes TrueArb as generating waveforms point-by-point, never skipping any (but has a lower 75MSa/s rate). The TGF4000's design has a flat 400/800 MSa/s rate, but I'm not sure whether it 'skips' points or not, exactly. Does it have a mathematical representation in memory, and can output a point anywhere on that curve (hense the 2.5ns/1.5ns jitter?), or something? I'm pretty weak in this area of knowledge so PLEASE correct me if I'm wildly misunderstanding something!If the above is correct, are both designs perfectly adequate to construct small waveform detail, considering the output bandwidth of the generator?:TGF4000:40MHzARB @400MSa/s, 80MHz ARB @800MSa/s for the various models.SDG2000X:20MHzARB @75MSa/s (TrueArb), @300MSa/s (DDS)Or, are there one or more deficiencies to the flat 400MSa/s design without (apparently) a TrueArb equivalent.I am considering buying one, but the obvious drawbacks are:14-bitTGF4000 vs16-bitSDG2000X (Theideaof the lower resolution really pains me, but I'm not sure if it would actually affect me in practice.)Small TGF waveform memory (I probably don't care)Lower sine wave max. freq for the models I can afford (40 or 80MHz TGF vs up to 120MHz SDG2000X)No automatic Siglent Bode-plot integration w/ my scope, but I imagine I can create/modify some scripts to still accomplish it.No harmonic output (SDG2000X has up to 16th harmonic, or 16 harmonics picked from a larger number, not sure how to interpret)Am I missing any other big drawback, or are any of these clear deal-breakers?The rest of the specs of the TGF4000 like resolution of various parameters, channel crosstalk, inputs, etc. seem really great (besides my uncertainties of the ARB jitter above).=== EDIT ===After sleeping and putting fresh thought into it, I suppose the 2.5ns jitter is DDS 1-clock jitter, which the SDG2000X would also have if switched from TrueArb to DDS mode.The tradeoffs are tough between the models.

author: nctnico
author_rank: Super Contributor
timestamp: August 07, 2020, 05:10:08 pm
content: Meanwhile I ordered & received a TGF4042 and put it back in the box after less than half an hour. It has exactly the same problem as many cheap function generators; low frequencies have an offset. I test this by outputting a 10MHz wave and a 1Hz wave. These should stay synchronised but on the TGF4000 they aren't.

author: Mechatrommer
author_rank: Super Contributor
timestamp: September 04, 2020, 01:39:11 am
content: Quote from: nctnico on August 07, 2020, 05:10:08 pmmaybe because how the DDS chip works, time multiplication will not be the same factor (100ns) when generating 10MHz and 1Hz signal. maybe what you are looking for is disciplined oscillator with 1pps output? or maybe rubidium grade oscillator