Base　on　the　thermal-electric　feedback　network　analysis,　the　thermal　stability　factor　S　is　presented　to　express　the　thermal　stability　of　the　device.　It　is　shown　that　the　self-heating　effect　is　compensated　completely　and　the　electrical　characteristic　of　device　won＇t　shift　when　S=0.　Furthermore,　the　expression　of　the　minimum　ballasting　resistance　RC　of　HBT　to　compensate　the　self-heating　effect　is　presented　taking　into　account　of　the　temperature　dependence　of　emitter　current,　the　valence-band　discontinuity　at　emitter　junction　(ΔEV),　the　bandgap　narrowing　due　to　heavy　doping　(ΔEg),　additional　ballasting　resistance　in　emitter　and　base　(RB　and　RE)-　It　is　found　that　the　higher　the　temperature　T　is,　the　smaller　the　minimum　ballasting　resistance　RC　to　compensate　the　self-heating　effect　is.　The　agreement　between　theory　and　experiment　is　shown　to　be　excellent.　Because　of　the　reducing　of　ballasting　resistance,　RF　power　HBT　will　provide　higher　output　power,　power　gain,　and　power-added　efficiency　(PAE)　in　an　amplifier　block.　©　2006　IEEE.