A new emitter finger layout in SiGe HBT to reduce thermal-coupling is presented in this study. By redistributing the emitter fingers of various SiGe HBTs, the thermal resistance reduces significantly from 133 to 88 K/W under room temperature. Thus, in dc performance, output conductance increases from -2.0 to -1.6 mA/V. In ac performance, the f(MAX) shows an improvement over 10%. In power performance, the linear power gain, P-1 (dB) and PAEat P-1 (dB) increase by 0.5 dB, 1.5 dB and 6.2% at 1.8 GHz, respectively. (c) 2007 Elsevier Ltd. All rights reserved.