Chopper. Bottom section is a normal gate controlled bi-directional router. Top section is based on a 70s delta modulator, at least in concept. The signals being switched are also the ones controlling the switching, plus you can add CV to that, good luck trying to work out what is going on once that happens.
mouser cart (use as a guide!): http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=d84981e335