cancel
Showing results for 
Search instead for 
Did you mean: 
Highlighted
Newbie
Newbie
301 Views
Registered: ‎09-05-2019

why TX Serial Clock = Data Rate / 2 in GTX/GTH

How does the line rate doubled?

TX driver.JPG
0 Kudos
3 Replies
Highlighted
Adventurer
Adventurer
273 Views
Registered: ‎05-07-2018

Re: why TX Serial Clock = Data Rate / 2 in GTX/GTH

Hi

transmitting & receiving data will be done with DDR.( Dual Data Rate )

Highlighted
Teacher
Teacher
236 Views
Registered: ‎07-09-2009

Re: why TX Serial Clock = Data Rate / 2 in GTX/GTH

can you expand upon your question please,

If the serial data rate is 10 Gb/s the serial clock does not equal 5 GHz.

Im taking a big guess here,

    If you think of a data rate of 10M bit per second, and draw it out, each bit is 100 ns wide,

          If that data was 1 0 1 0 1 0 1 0   and you draw it out,

             then as above each bit is true for 100 ns, 

                 the period between two rising edges is 200 ns. 

 

And 200 ns period is 5 MHz.

 

BUT, 5 Mhz is NOT the clock frequency, its the fundamental of the data,

    if you were to send a random stream of 1 and 0 out at 10 Mb/s, then you woud see on a spectrum analyser the fundamental at 5 MHz, and harmonics,   I leave that as a exerics for the reader to predict what frequencies the harmonics would be at ..

 

                 

<== If this was helpful, please feel free to give Kudos, and close if it answers your question ==>
0 Kudos
Highlighted
Xilinx Employee
Xilinx Employee
179 Views
Registered: ‎08-07-2007

回复: why TX Serial Clock = Data Rate / 2 in GTX/GTH

hi @agilulf 

 

tx serial data is updated on both rising edge and falling edge of the clock.

so clock frequency is line rate divided by 2.

 

Thanks,

Boris

------------------------------------------------------------------------------
Don't forget to reply, give kudo and accept as solution
------------------------------------------------------------------------------
0 Kudos