I would like to know the "why" of this project, and about the signal that needs to be attenuated (sine wave, NRZ, RZ, etc.), and the impedance characteristics of the source and sink, and how important dc preservation is, and what levels of accuracy and precision are required in the attenuation, and all price/availability constraints. In other words, complete requirements. Otherwise, it sounds too much like a homework assignment without showing existing work.
There are many RF attenuators that have flat passbands well in excess of 10MHz, are rated down to dc or close to it, and only cost about $3 each thanks to mass production of mobile handsets. Peregrine Semiconductor and M/A-COM are manufacturers to search for.