As far as I know, the highest standard for minimum write speed on a SD card is V90 (90 megabytes per second). To achieve 1 gigabit per second would require something on the order of V150 (120 megabytes per second, as Davidgp says, plus a bit of a buffer). Most of the speed claims beyond V90 are read speed only, and the cards that claim higher write speeds (the Sony David linked to, plus top cards from several other manufacturers) don't guarantee it as a minimum - several cards claiming hundreds of megabytes per second don't carry any certifications beyond U3 - they only guarantee 30 megabytes per second sustained, although they have a much higher burst capability. Again, as far as I know, the only standard media that is capable of that kind of write speed is XQD. CFExpress, a forthcoming descendent of XQD, will be even faster, easily capable of handling even 4K RAW video, although capacity will be a problem...