Hello all!
I need advice from you. Iam working on one project where i need extremly high quality converting. But one huge problem is how to sync individual cards. Iam distributing wordclock over backplane and i need maybe just high quality divider for frequency 48kHz -192kHz or some jitter cleaner and divider or some pll with low jitter on each card. For example on each card will 4 inputs or outputs.
Distributed Word Clock i want to get from GPS module so it should has jitter >1ps i hope. But problem is that i want the same low jitter on each card. Could you please help me with some IC-s or webpages?
Many thanks
I need advice from you. Iam working on one project where i need extremly high quality converting. But one huge problem is how to sync individual cards. Iam distributing wordclock over backplane and i need maybe just high quality divider for frequency 48kHz -192kHz or some jitter cleaner and divider or some pll with low jitter on each card. For example on each card will 4 inputs or outputs.
Distributed Word Clock i want to get from GPS module so it should has jitter >1ps i hope. But problem is that i want the same low jitter on each card. Could you please help me with some IC-s or webpages?
Many thanks
So now i decided to use FPGA just for divide WCLK from 192kHz to 96kHz and 48kHz. I will use combinational circuit so there should be low jitter and i will use internal pll to multiply wclk to bclk and mck. do you think it will be fine?
so 117 views and any reply. What is wrong with you guys? No one can help? I thought this is high-fi forum... But if someone writes about 3886 ...
You ,ay have to look at signal integrity issues, do you have a schematic of the clock distribution including connectors it will be going through and track lengths...
I don't understand what you are trying to tell...
Word-Clock is a standard, which any decent audio card understood. Many can sync to an 48 kHz clock even if they are using 96 kHz internaly... There are also Word-Clock generators with setable outputs.
Word-Clock is a standard, which any decent audio card understood. Many can sync to an 48 kHz clock even if they are using 96 kHz internaly... There are also Word-Clock generators with setable outputs.
So question is, how to generate low jitter clock for converters (from word clock)? Do you have any tested PLLs or some tested circuits? And how high jitter is fine? I think in professional High-end aplications.
A good start is a google search for clock distribution buffers/dividers e.g. from IDT...
Low Voltage Differencial Signaling Logic (LVDS) buffers are especially good in minimizing skew.
Low Voltage Differencial Signaling Logic (LVDS) buffers are especially good in minimizing skew.
OK i will try it again, i have distributed word clock with on frequency 192kHz. on each card i need to clock multiple adc and dac. My questions is, do you have any tested circuits or IC-s? ive googled it for a long time and now iam trying to ask you.
What is wrong with simply routing your clock output to the adc/dac clock inputs? Maybe with a buffer tree...
I have about 24 cards and every card is changable, so you have 24 cards and on each card are 8 converters, i have one control card which generates word clock. Each card can be in or out and can be clocked with different clock...
wow - 192 converters .... what are you doing with such a large number of adc? I would be really interested to hear some details!
You could put one 74HC245 buffer at each card with VCC=3.3Volt.
Each of the 8 outputs goes to one converter.
Use some series resistance at the output of each buffer to match line impedance.
The buffer needs at least 1uF ceramic cap and a good ground plane as all outputs are switching simultaneously.
The control card generates word clock and this goes to an 74LVC245 buffer with VCC=3.3Volt.
Connect two LVC outputs together with 10 Ohm.
The four LVC outputs go to a 75 coaxial cable. Each coax connects 6 cards together.
The last of the 6 cards has an 75 Ohm termination resistor.
Alternatively you can use PECL logic for clock distribution.
Use converters with adjustable clock multipier - so you only need 48kHz. Alternativly use flip flops at the clock generator for dividing (be careful with timing).
Greetings,
Udo
You could put one 74HC245 buffer at each card with VCC=3.3Volt.
Each of the 8 outputs goes to one converter.
Use some series resistance at the output of each buffer to match line impedance.
The buffer needs at least 1uF ceramic cap and a good ground plane as all outputs are switching simultaneously.
The control card generates word clock and this goes to an 74LVC245 buffer with VCC=3.3Volt.
Connect two LVC outputs together with 10 Ohm.
The four LVC outputs go to a 75 coaxial cable. Each coax connects 6 cards together.
The last of the 6 cards has an 75 Ohm termination resistor.
Alternatively you can use PECL logic for clock distribution.
Use converters with adjustable clock multipier - so you only need 48kHz. Alternativly use flip flops at the clock generator for dividing (be careful with timing).
Greetings,
Udo
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