Based　on　the　electro-thermal　feedback　model　for　multi-finger　power　SiGe　heterojunction　bipolar　transistor　(SiGe　HBT),　this　article　analyzes　the　effect　of　base　heavy　doping　on　thermal　characteristic　of　SiGe　HBT.　Because　of　the　effect　of　base　heavy　doping,　SiGe　HBT　will　produce　bandgap　narrowing　which　decreases　the　collector　current　density　and　affects　the　device　thermal　distribution.　By　analyzing　the　thermal　characteristic　of　multi-finger　spacing　SiGe　HBT,　we　find　that　increasing　base　doping　can　decrease　the　current　density　and　the　temperature　of　emitter　finger,　which　suppress　the　emitter　finger　thermoelectric　positive　feedback　and　improve　the　device　thermal　stability.　©　2011　IEEE.