In　order　to　solve　the　energy　consumption　problem　of　active　RFID　tag　and　prolong　the　battery　life,　a　passive　RF　activation　circuit　without　source　power,　which　composed　of　diodes　and　capacitors,　is　studied　in　this　paper.　The　circuit　collects　and　converts　RF　energy　to　DC　power.　Therefore,　it　does　not　need　power　supply　and　can　efficiently　decrease　the　power　consumption.　The　electromagnetic　co-simulation　simulation　results　show　that　the　circuit　can　generate　about　1.5V　DC　stable　output　when　the　antenna　absorbs-20dBm　RF　power　(Standard　RFID　power　signal　is-10-50dBm,　so　average　figure　is　chosen　here).　It　is　very　suitable　for　application　in　electronic　documents　and　device　management　with　their　normal　operation　voltage　always　1-2V.　©　2018　IEEE.