sql begin end week of year

I do cant get the begin and end week between two dates in Sql Server? for example:

    begin       end
    2016-04-25  2016-05-01
    2016-05-02  2016-05-08
    2016-05-09  2016-05-15
    2016-05-16  2016-05-22
    2016-05-23  2016-05-29
    2016-05-30  2016-06-05
...

Regards!