I. INTRODUCTION

ETEROJUNCTION bipolar transistors (HBTs) are widely used for the RF and high speed applications. First commercial HBT was made of AlGaAs/GaAs material and that composed material was used very often earlier. The range of modern HBT transistor is wide and the most attractive for RF application are SiGe/Si HBT, InGaAs/InP HBT, InGaP/GaAs HBT, etc Silicon-Germanium (SiGe) technology is the driving force behind the explosion in low-cost, lightweight, personal communications devices like digital wireless handsets, as well as other entertainment and information technologies like digital set-top boxes, Direct Broadcast Satellite (DBS), automobile collision avoidance systems, and personal digital assistants. SiGe extends the life of wireless phone batteries, and allows smaller and more durable communication devices. The heart of SiGe technology is a SiGe heterojunction bipolar transistor (HBT). Another advantage of SiGe technology is the capability to be integrated in CMOS circuits, enabling production of cheap highperformance BiCMOS integrated circuits.