Comparison of low frequency noise and high frequency performances of double and simple polysilicon Bi-CMOS BJT

The issue of this paper concerns 0.35 mum Bi-CMOS double polysilicon bipola r transistors and 0.5 mum Bi-CMOS simple polysilicon bipolar transistors. L ow-frequency noise measurements are performed. Noise spectral densities are analysed versus bias and geometry. From these noise measurements, base and emitter series resistances are extracted. A comparison of both technologie s is done. Though double polysilicon transistors have a more complex struct ure than the simple polysilicon ones, they exhibit similar or even better p erformances. Indeed, DC characteristics and noise levels are equivalent for both technologies. Double polysilicon transistors exhibit a reduction of t he base resistance and a significant improvement of the transition frequenc y f(T) is obtained. (C) 2000 Elsevier Science Ltd. All rights reserved.