IO Pad max frequency Calculation

[shyam4908]

Hi,

What are the parameter needs to be considered for calculating max frequency of IO pad in FPGA...Say for example IO pad with voltage 2.5V and drive strength of 16mA...I know that we need to used the DC switiching characterstic of the device..but not sure on parameter needs to be considered..can some one help on this..with virtex5 as taking example

thanks in advance

 

[sameh_yassin99]

Hello,
To answer the question "What is the max frequency that I can use?" I think you should firstly read the "clock management" section found in the part data-sheet. For example in Virtex 6 see page number '5' in ds150.pdf.

Then, you should read carefully the clock distribution, how clocks are classified as global clocks, regional clocks and IO clocks in ds152. You will maximum frequency for different parts. For example at page '36' you can find Input/Output Delay Switching Characteristics. You can also find details for BRAM and transceivers etc..

Finally, the amplitude of signal voltage is not a big concern when dealing with frequency. Think of and RF signal that has very small amplitude (order of 2 uV) and a serial stream of a gigabit transceiver (order of 2 Volts), both of them can have any frequency.

regards,