A　novel　segmented　emitter　structure　with　nonuniform　finger　length　and　spacing　has　been　presented　to　alleviate　adverse　thermal　effects　in　multi-finger　SiGe　HBT　power　device.　Considering　the　various　thermal　resistances　of　different　components　for　the　segmented　multi-finger　HBT,　an　appropriate　thermal　model　is　developed.　Using　this　model,　the　thermal　simulation　for　a　ten-finger　power　SiGe　HBT　with　segmented　emitter　structure　is　performed　and　the　three-dimensional　temperature　distribution　on　emitter　fingers　is　obtained.　Compared　with　traditional　emitter　structure,　the　maximum　junction　temperature　reduce　significantly　from　416.3K　to　405K,　the　thermal　resistance　reduce　from　154.67K/W　to　140K/W,　thus　the　thermal　stability　of　improved　structure　is　enhanced　apparently(1).