Virtex® Family FPGAs

[assaf_malki]

Hey guys,

I'm using Virtex-5 ML507.

I'm trying to use the Frequency Synthesizer (ICS843001-21) which is on board.

I've configured the DIP switches (SW6) according to the User Guide to produce a 155.52 MHz clock (for example).

According to the user guide, when J54 is shunted, the clock is driven out to the SMA connectors, J12 and J13, I can also see it in the schematic.

However, I use the scope, I've connected it to the J12 connector and I see nothing.

Am I missing something?

Thanks a lot.

Assaf.

[alaney]

You need to add a 100R termination across the diffrential pair to see an output.

[assaf_malki]

Ok,

So when I connect it to the SMA_DIFF_CLK_IN in J10 connector which from my understanding, is the dedicated input clock to GTX_X0Y5, it uses it without a problem, right?

Another thing, I want to work with a speed of 1.6 Gbps, for that I need a clock of 80 Mhz, ICS843001-21 can't give me that clock according to the user guide, is there a way to work around it without using GREFCLK?

Can I config ICS843001-21 to give me that clock?

Thanks a lot.

Assaf.

[mcgett · Accepted solution]

> You need to add a 100R termination across the diffrential pair to see an output.

The SMAs are driven from a ICS85401 device with LVDS outputs.  While a 100 ohm termination would present a cleaner eye on the scope it is not necessary.  The absence of any signal, with the jumper on J54, would indicate that that something else is wrong.

[assaf_malki]

That's wierd.

All I need to do is to turn on the ML507 and setup SW6 (and put the J54 jumper on), right?

Thanks a lot.

Assaf.

[assaf_malki]

Ok,

I can see the clock, the connection with the scope was wrong.

Thanks a lot.

Assaf.

[assaf_malki]

Well, I figured out a way to get that 80 Mhz clock.

I use 25 Mhz clock with M = 32 and N = 10.

The problem is that I take VCO all the way to 800 Mhz, is that ok?

Thanks a lot.

Assaf.

[mcgett]

According to the ICS843001 datasheet a VCO of 800 MHz is outside of the operating range of the device.