hi

can any one guide which circuits are usually used to split the data bit stream into +/- I and +/-Q for being modulated on pair of quadrature carriers (specifically for high freq > 10G)

Thanks

 

You are talking about a quadrature modulator.

One good way is to start with a self-contained quadrature modulator. Below is the link to just one classical mdoulator but there are many available.
ADL5385

This web page gives a good overview. Please pay special attention to the Tayloe modulator.
I and Q Phasing Modulators