Modelado, simulación y medida de la compresión en LNAs para aplicaciones de astronomía

Abstract

In this work, system level modelling and realistic simulation and measurement results of a 31 GHz Back-End Module (BEM) Low-Noise Amplifier (LNA), designed for the QUIJOTE CMB (Q U I JOint TEnerife CMB) experiment radiometer, are reported. The signals received by radiometers can be identified as continuous spectre gaussian white noise signals. This makes necessary time-domain simulation techniques and appropriate models for the realistic analysis of radiometers behaviour. The measured-based modelling of one BEM´s LNA, its simulation in nominal conditions and the measurement of the nonlinear characteristic by using filtered white noise excitation signals, will be shown. Typically, in the LNAs design process the linearity is not taken into account but, as we will see, in the radiometers case, the nature of gaussian noise excitation signals makes amplifiers to present higher nonlinearity in their characteristics than when using single tone excitation signals. Therefore, in order to analyze the suitability of the LNAs nominal operation, linearity figures of merit have to be obtained, but using realistic excitation signals. In this paper, the LNAs nonlinear characteristics with gaussian noise excitation signals have been obtained by simulation and measurement.