Ultra-low-power and high-speed SiGe base bipolar transistors for wireless telecommunication systems

Ultra-low-power and high-speed SiGe base bipolar transistors that can be used in RF sections of multi-GHz telecommunication systems have been developed. The SiGe base and a poly-Si/SiGe base-contact were formed by selective growth in a self-aligned manner. The transistors have a very small base-collector capacitance (below 1 fF for an emitter area of 0.2/spl times/0.7 /spl mu/m) and exhibit a high maximum oscillation frequency (30-70 GHz) at low current (5-100 /spl mu/A). The power-delay product of an ECL ring oscillator is only 5.1 fJ/gate for a 250-mV voltage swing. The maximum toggle frequency of a one-eighth static divider is 4.7 GHz at a switching current of 68 /spl mu/A/FF.