The effects of geometrical scaling on the frequency response and noise performance of SiGe HBTs

We examine the geometrical scaling issues in SiGe HBT technology. Width Scaling, length scaling, and stripe-number scaling are quantified from a radio frequency (RF) design perspective at 2 GHz. We conclude that a SiGe HBT with emitter area A/sub E/=0.5/spl times/20/spl times/6 /spl mu/m/sup 2/ is optimum for low noise applications at J/sub c/=0.1 mA//spl mu/m/sup 2/ and f=2 GHz using the design methodology, which guarantees optimal noise and input impedance matching with the simplest matching network. Finally, the optimal device sizes at f=4 and 6 GHz for low noise applications are also obtained using the same method.