Asynchronous I2S FIFO project, an ultimate weapon to fight the jitter

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iancanada

iancanada

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AR2 said:
Hi guys,
I was wondering if any of you have solved this puzzle. Ian's S/PDIF board in its output uses U.FL connectors. Acko's DAC at input uses W.FL Hirose connectors. Any idea how to connect those two? I do not think they make any crossover cable that has both types of connectors. The only idea I have is to somehow switch U.FL connectors from S/PDIF board to W.FL, which I am sure is less than optimal from mechanical stand point, but I believe only possible one. Obviously my intention is to use those prefabricated cables, as they seem like really good solution.
Now I hope someone had a same problem with better idea. I absolutely hate those ultra small connectors. U.FL are quite fine and I hope Acko will replace his at some point to the bigger ones.
Click to expand...

Hi AR2,

I really love those u.fl connectors and cables. They make the signal quality much better then any other regular cables. I tend to use them as possible as I could, you can say that:).

Actually, anything before clock board is not that immportand, especially with the isolator board. Having nothing wrong on data is the only thing I ask for. So, ph2.0mm calbles don't have any problem. Only need ground wires between signals if Fs higher then 176/196KHz. However, anything after clock board is critical. So, coaxial (U.FL) cable is almost a must for those low jitter high speed applications.

I didn't try w.fl. Seems a bit diffcult to solder. Fortunately, qusp mentioned that w.fl can share same footprint as u.fl. Replacing those smt sockets is very easy.

I'm afraid there would be kind of w.fl to u.fl bridge cable, but I just couldn't source it.

Ian
 
iancanada

iancanada

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marce said:
The GND (return path) should be adjacent to the signal, when you start getting into 100MHz signals, you can easily inroduce signal integrity problems. The main concern is avoiding impedance mismatches as you go from on board to another, and distance is also critical, they dont like going a long way, depending on the driver, receiver and cable used for transmission.
Samtecs range of high speed cables to give you an idea of what is used for high speed signal transmission:
Samtec | High Speed Cable Assemblies
Another methos widely used is either FPC/FFC connectors and cables or bespoke two plus layer flex caqbles with a ground plane and the respective connectors. Preferably the signal should travel over a contigous return plane (GND) from transmittor to receiver, or if only one or two signals then co-ax cable with rf connectors.
The frequencies that are of concern are determined by the knee frequecy:
Fknee=1/2tr where tr is the 10-90% rise time of the signal.
This is also the determining factor on whether a design is high speed, not the ultimate clock frequency.

The following links are some of the main people for signal integrity:

beTheSignal.com
Signal Consulting, Inc. - Dr. Howard Johnson
Speeding Edge consultants specialize in high-speed PCB and system design disciplines
Click to expand...

Hi marce,

Thank you for sharing your RF knowledge with us. You are expert on RF and high speed layout design. I always have to keep in mind those tips with my designs, otherwise I will have troubles in those EMC labs. Passing all the EMC tests is a basic requirement for FDA registration.

Totally agree with you, RF signal has to be treated as analog signal. Clock signal have to be treated as RF signal.

Do you have some on line simulation on RF signal transmition over coaxial cable or transmition line? If so, that would much easier to understand the principles.

Talking about the raising time, matching on the source with a serial resistor is a very common method, but it will make the rasing edge a bit slower. Or, you have to use end termination. I'm not quite sure which way is better for the low jitter performance, with or without. On the new designed Si570 clock board, I'll leave a optional u.fl socket footprint for a MCLK signal without source serial resistor, will see, which way is better :D.

Ian
 
AR2

AR2

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Joined 2002
burningamp.com
Ian and Qusp,

Thank you for the prompt reply. Yes I am clear that besides clock, any other cabling is done without U.FL cables. I have it put together with cables provided by Ian. I did replacement of U.FL to W.FL connectors, previously on my LightHarmonics USB to I2S board, because of the same problem - incompatibility with ACKOP board. I was just hoping someone is smarter ( not hard at all) and found some better solution. W.FL connectors are very small, compared to U.FL that are much easier for handling. Yes it is correct that w.FL will fit into U.FL footprint, but knowing how tight is connection between cable and plug, I always worry that I will pull trace with that little bugger, even if I am using that expensive tool, that I purchased. With U.FL socket in its place, at least I have a feel that connection between board and socket is much stronger.
Thanks a lot guys!
 
iancanada

iancanada

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BOM of standard configuration of Passive Battery Management Board

Testing group start receiving the PCB. Someone may get bit confusion on the schematics and BOM. Actually the standard configuration is very simple, just a couple of components. I post a picture of this configuration below. It should be a good start point. More features could be added step by step later on. Just hope it’s clear enoughJ.

(nothing on the bottom side)

Ian
 

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iancanada

iancanada

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bigpandahk said:
After burnt in the isolator board for a week, details are increasing with much quite background. I still have not isolate the I2C as RS has not delivered my order yet.:mad:

I hope other testers can also report their progress.
Click to expand...

You mean you have already ordered the I2C isolator? I usually receive digikey orders in two days.

Please confirm the datasheet with the PCB footprint, I didnt do it.

Ian
 
qusp

qusp

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Joined 2009
no, not on the board, but in lightning quick response to a suggestion, Ian whipped up this separate isolator, which doesnt just isolate USB, it isolates everything. its placed between the fifo main board and the reclock board, so everything including the fifo CPU itself is isolated immediately before the reclocking process, a much better idea if I do say so myself =) placed here it makes it so the reclock board and clock become part of the dac, not part of your source.

at this stage only the prototypes have been sent out to testing after Ian verified it himself, in fact pretty much the last 20 pages have been about the battery board, Si570 clock board interest list and the isolator.

so its not available for purchase just yet, not till we've finished our testing, but I feel confident it will be standard issue for most people from now on.
 
G

ggking7

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Joined 2010
What about this configuration:
USB isolator (ADuM4160 USB Isolator board by Circuits@Home [CAH-ASSY-UI] - 44,90*€ : lipoly.de, Alles für den Elektromodellflug.) - to - USB to I2S Audio Widget (Q N K T C USB-I2S Module and Analog Board) - to - I2S FIFO - to - DAC
Click to expand...
I believe that isolator uses a switching regulator. Here is an alternative with a linear reg:

Ultravox - SGD70.00 : Welcome to the diyparadise e-store!

That said, I noticed an "unlivening" of the sound when using it that was confirmed by a well-known DAC designer. It did seem to cut PC noise though, with a blacker background and less brightness.
 
iancanada

iancanada

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Assemble Si8605AD I2C/USART digital isolator to the FIFO isolator board

Si8605 arrived yesterday. I assembled it to the isolator board. It will work for ESS9018 with external controller. Just fit the reserved PCB footprint on the FIFO isolator board. Pull up resistors might be required for the I2C bus on both sides.

Digikey P/N: 336-2053-5-ND

Ian
 

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C

coolhead

Member
Joined 2010
iancanada said:
Si8605 arrived yesterday. I assembled it to the isolator board. It will work for ESS9018 with external controller. Just fit the reserved PCB footprint on the FIFO isolator board. Pull up resistors might be required for the I2C bus on both sides.

Digikey P/N: 336-2053-5-ND

Ian
Click to expand...

Ian, it Looks beautiful.
I couldn't keep up with your update, I think that is a good sign for lazy people like me to keep reading.

I received your power management board, I just want to confirm the resistors to make sure I didn't do a silly mistake:
1. R1, 2, 5, 6, 8, 10 are 0ohm
2. R11 is 100ohm
3. R3, 4, 7, 9 are 1kohm
4. R12, 13 are short because my -ve is Gnd

Thanks.
 
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