Video Tutorial on the Theory, Design and Characterization of Delta-Sigma ADCs - Page 1
Forum section: electronics / projects

author: Hugoneus
author_rank: Frequent Contributor
timestamp: August 04, 2014, 02:54:04 am
content: In this episode Shahriar explores the world of Delta-Sigma modulators with emphasis on a Delta-Sigma Analog to Digital Converter (ADC). The basic concepts of analog to digital conversion is presented, particularly with respect to quantization noise spectral shape and power density. Next, oversampling ADCs are presented to demonstrate the possibility of increasing SQNR (ENOB) through manipulation of quantization noise spectrum.Due to the practical limitations of high oversampling ratios, delta-sigma modulations is explored. The principle operation behind delta-sigma ADCs is presented with detailed explanation on noise shaping, filtering and decimation. The signal and noise transfer functions for a 1st order and 2nd order delta-sigma ADC are derived. Finally, as a practical example, a 2nd order delta-sigma ADC based on a 1-bit quantizer is presented. The ADC uses two Miller integrator op-amps, one comparator and a D-Type flip-flop. The complete measurement of this delta-sigma ADC is presented. The impact of over sampling ration, op-amp linearity and input signal bandwidth is presented. The slides for this video can be downloaded from The Signal Path website.You can watch the video here: [1 Hour & 1 Minute]http://youtu.be/z9u-QTDAeaMMore videos at The Signal Path:http://www.TheSignalPath.com/

author: Vgkid
author_rank: Super Contributor
timestamp: August 04, 2014, 03:50:27 am
content: I look forward to watching this video tomorrow.

author: andyturk
author_rank: Frequent Contributor
timestamp: August 04, 2014, 05:55:15 am
content: Great stuff! I've been trying to figure out how MEMS microphones work (with PDM data output) and your video helped a lot. I wish I understood more of the theory though.The effort you put into these videos must be tremendous. Amazing job. Thanks.

author: vaualbus
author_rank: Frequent Contributor
timestamp: August 04, 2014, 10:05:55 am
content: On of your best tutorial. Really good.I have just one question: so the flio flop (i suppose a 7474) is connect how? Gnd at -5 at vcc at 5v? I never see a logic device connect so. Why the the component still work?And why you select a open collector op amp?Best regards alberto.

author: Hugoneus
author_rank: Frequent Contributor
timestamp: August 04, 2014, 01:08:27 pm
content: Quote from: vaualbus on August 04, 2014, 10:05:55 amThanks!Voltage is all relative. So by connecting the VDD of the flip-flop to 5V and its GND to -5V, it will produce logic between +/-5V. You just have to make sure that you keep all your voltages consistent between the components. I used an open-collector comparator because that was the only one I could at the moment. O0

author: vaualbus
author_rank: Frequent Contributor
timestamp: August 04, 2014, 01:58:12 pm
content: ok thanks.By the way keep on doing this advanced tutorials, they are more interest than the base one!And also repair videos are good.And a tutorial on PLL and FracN synthetized tecqnique would be ineterst.Best regards, Alberto

author: w2aew
author_rank: Super Contributor
timestamp: August 04, 2014, 06:26:08 pm
content: Shahriar - as I commented on your video - very nice! I really like the process of going from theory, to practice, to real-world effects. I try to do a bit of that on my videos too, although I don't typically go as deep in the theory as you do. Great job!

author: Lukas
author_rank: Frequent Contributor
timestamp: August 04, 2014, 07:24:42 pm
content: Great stuff as usual! I especially like the connection between theory and application. All of a sudden the content from university begins to make sense

author: HighVoltage
author_rank: Super Contributor
timestamp: August 04, 2014, 07:29:01 pm
content: I learned a lot of new and interesting stuff from your great video.Thank you so much

author: Mechatrommer
author_rank: Super Contributor
timestamp: August 04, 2014, 07:50:04 pm
content: thats the "signal path" talking allright. rare! thank you!

author: German_EE
author_rank: Super Contributor
timestamp: August 04, 2014, 09:22:04 pm
content: Shahriar, please talk a little slower on your videos. I know that you have a lot to cram into a one hour video but some of us do not have English as a first language.The video was however very interesting, thank you.

author: deephaven
author_rank: Frequent Contributor
timestamp: August 04, 2014, 09:27:58 pm
content: Excellent video as usual

author: Hugoneus
author_rank: Frequent Contributor
timestamp: August 05, 2014, 01:23:37 am
content: Quote from: German_EE on August 04, 2014, 09:22:04 pmI'll do my best.

author: IanB
author_rank: Super Contributor
timestamp: August 05, 2014, 02:13:07 am
content: Quote from: German_EE on August 04, 2014, 09:22:04 pmI appreciate the trouble following fast speech, but at least with a video you can pause and replay parts that are difficult to follow.On the other hand if the presenter speaks too slowly it is not so easy to speed things up.

author: Hugoneus
author_rank: Frequent Contributor
timestamp: August 05, 2014, 02:56:37 am
content: Quote from: IanB on August 05, 2014, 02:13:07 amThere is no script for the videos. I just say what comes to mind and I tend to speak faster when I do that.

author: IanB
author_rank: Super Contributor
timestamp: August 05, 2014, 03:04:09 am
content: Quote from: Hugoneus on August 05, 2014, 02:56:37 amFor myself, I appreciate a rapid pace of delivery. It makes things more lively. I didn't feel you were speaking too fast, but I'm used to it.Interestingly, American commenters often complain that British presenters speak too fast, while British commenters complain that Americans speak too slowly. That's a curious cultural difference.

author: EEVblog
author_rank: Unknown
timestamp: August 05, 2014, 03:47:08 am
content: Quote from: wilfred on August 05, 2014, 03:39:45 amWhy? This is where the original thread is, Shahriar posted it here himself and also replies here.Rude would be to post here and instruct people to discuss on another forum

author: Hugoneus
author_rank: Frequent Contributor
timestamp: August 05, 2014, 04:03:09 am
content: Quote from: wilfred on August 05, 2014, 03:39:45 amI appreciate your concern Wilfred. My goal is to reach a wide audience and Dave's forum has a lot of users. As you know I have no advertisements on my site anyway, so traffic to my forum is only beneficial as far as getting people to discover new videos. Commenting on my YouTube videos, subscribing and liking the videos is the best because it shows manufactures a high degree of engagement to my videos and makes it more likely for them to want to work with me.Cheers!

author: Mechatrommer
author_rank: Super Contributor
timestamp: August 05, 2014, 04:53:35 am
content: i wish i can post in signalpath_forum but it stagnant and i believe mr hugoneous is not a regular forumer/admin. i agree with slowing/pausing down fast pace video, i also not native speaker. slow pace 5 hours videos and nearly 1GB of the same content is not fun.

author: HighVoltage
author_rank: Super Contributor
timestamp: August 05, 2014, 08:52:08 am
content: Quote from: German_EE on August 04, 2014, 09:22:04 pmOne other way is to download the video and play it with VLC and slow down the playback by 10% or so.It has helped me to understand a few things in documentaries or movies.

author: HackedFridgeMagnet
author_rank: Super Contributor
timestamp: August 05, 2014, 01:10:28 pm
content: Verbal typo @ 25:20 2.5 bit is 15db not 9db.Great video. Thanks.

author: Hugoneus
author_rank: Frequent Contributor
timestamp: August 05, 2014, 02:02:06 pm
content: Quote from: HackedFridgeMagnet on August 05, 2014, 01:10:28 pmYes! I multiplied 6 by 2.5 and somehow got 9...

author: HackedFridgeMagnet
author_rank: Super Contributor
timestamp: August 05, 2014, 02:42:07 pm
content: Just wanted to prove I was paying attention.

author: w2aew
author_rank: Super Contributor
timestamp: August 05, 2014, 04:39:46 pm
content: Quote from: Hugoneus on August 05, 2014, 02:02:06 pmNo worries, happens to me all the time. One of my latest videos, I converted 29 feet into 88.4cm instead of 884cm! Duh! That's why YouTube has "annotations". A lot of my videos have post-publishing annotations to fix my goof ups!

author: Hugoneus
author_rank: Frequent Contributor
timestamp: August 05, 2014, 07:14:22 pm
content: Quote from: w2aew on August 05, 2014, 04:39:46 pmWhat you guys don't know is that at the last minute I decided to add some more decoupling caps to the board. I put one of them backwards... I turned it on and was setting up the camera before it exploded. Scared the hell out of me and my cat ran out of the room at nearly the speed of sound.

author: HackedFridgeMagnet
author_rank: Super Contributor
timestamp: August 05, 2014, 11:32:57 pm
content: QuoteShould've had the camera on for that one.As to your two quiz questions. IIRC.Q: Why not use the second channel of the Rigol to produce the input signal?A: Because they share common. You have the sample clock at 256khz +-5v. So the Rigol common is probably at -5v.But you want the input to be 2khz sine wave referenced to zero volts, so need to have the grounds floating between the two function gens.Q: What are the two remnant peaks on the FFT of the digital output.A:Warning I'm pretty hazy here.You said the spectral content of the digital out put is the same as the samples being convolved by the h(t) (hole? ). The twin lines (which are well outside the frequencies of interest) superimposed on the sinc function look like sidebands caused by the 2khz of the input signal.A couple of questionsWhere can I find out about this h(t) function? Have you a link? It seems to be just a step pulse for a finite duration.The sinc function from wikipedia looks a bit different.http://en.wikipedia.org/wiki/Sinc_functionIs the function h(s) more like (sinc(x))^2 than sinc(x)?

author: vaualbus
author_rank: Frequent Contributor
timestamp: August 06, 2014, 01:00:14 am
content: I would be better If the cap explode on video!By the way why you always use so many decoupling cap?There some calculation that is necessary to get the correct number?Best regards, Alberto

author: IanB
author_rank: Super Contributor
timestamp: August 06, 2014, 02:10:38 am
content: Quote from: vaualbus on August 06, 2014, 01:00:14 am"More is better"

author: EEVblog
author_rank: Unknown
timestamp: August 06, 2014, 03:17:36 am
content: Quote from: w2aew on August 05, 2014, 04:39:46 pmOf course, no one actually sees those annotations, so you still get emails and comments 5 years later...

author: EEVblog
author_rank: Unknown
timestamp: August 06, 2014, 03:20:49 am
content: Quote from: Hugoneus on August 05, 2014, 07:14:22 pmThe other week I used a PNP instead of NPN transistor on a breadboard and I was plugging it in "live" andBANGSomeone watching the live feed saw me jump back.

author: Hugoneus
author_rank: Frequent Contributor
timestamp: August 06, 2014, 03:39:15 pm
content: Quote from: EEVblog on August 06, 2014, 03:20:49 amOh yes, the classic move. Perhaps the worst thing that I have done in the lab (recently) was accidentally connect the GND of a scope probe to 50V while the GND of an adjacent probe was connected to an actual GND. Ruined two very expensive probes... Thankfully the scope was OK.

author: w2aew
author_rank: Super Contributor
timestamp: August 07, 2014, 01:34:20 am
content: Quote from: Hugoneus on August 06, 2014, 03:39:15 pmTwo words.... Blooper Reel.

author: w2aew
author_rank: Super Contributor
timestamp: August 07, 2014, 01:35:21 am
content: Quote from: EEVblog on August 06, 2014, 03:17:36 amYeah, you got that right! I've starting putting the annotations in big letters on an obnoxious color background so they get noticed! But, still get the comments...

author: electr_peter
author_rank: Unknown
timestamp: September 25, 2014, 05:34:29 pm
content: Very nice video about delta-sigma ADCs. Both theory and practical aspects are combined and subtle details are shown - very educationalI would not worry too much about video length - 1 or 2 hours are reasonable for such content.Quote from: HackedFridgeMagnet on August 05, 2014, 11:32:57 pmIs this really the reason two signal generators are used? I am not sure about this setup.Rigol outputs +/-4V square wave clock with common at zero volts (by the looks of the breadboard). Agilent provides +/- sinwave signal with common connected to 0V as well (as it looks).Additionally, common of both sig gens should be connected to mains earth, signals are common by default (unless one sig gen is floating?).Can someone explain sig gen connection and why two sig gens are needed in a bit more detail?I noticed that amplitude of output square wave slightly matches input sinwave (see scope shots with blue and yellow waveforms on video). Why is the signal amplitude changing - maybe ground is not stable or signal probing picks up noise via capacitive coupling?