Experience with bipolar front-end amplifiers and perspectives for LHC upgrade

The paper presents detailed noise analysis of detector front-end circuits employing bipolar transistors. The noise models of bipolar transistors are reviewed. Noise analysis of the front-end circuit is performed taking into account noise correlation effects in bipolar transistors. The obtained results on the equivalent noise charge are compared with the measurements performed for the front-end circuit used in the SCTA ASIC. The elaborated formalism of noise analysis is used for the evaluation of noise performance of a front-end circuit employing SiGe heterojunction bipolar transistors