Analysis of packaging effects and optimization in inductively degenerated commonemitter low-noise amplifiers

The effects of packaging on the performance of inductively degenerated common-emitter lownoise amplifiers (LNAs) are examined and the equations describing the input impedance, transconductance, voltage gain, and noise figure of the packaged amplifier are derived. From the equations, several guidelines for the LNA design are obtained and a systematic approach for the LNA design can be derived. Furthermore, by applying the formulas, the performance of the amplifier can be readily estimated and optimized in the very early stage of the circuit design, immediately as the process data is available. The measurement results of the implemented 0.35-(mu)m SiGe RF front-end with an inductively degenerated common-emitter LNA at 1.575 GHz agree well with calculations and simulations.