noise and other systematic effects in the Planck-LFI radiometers

¹ Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
² IASF-CNR, Sezione di Milano, via Bassini 15, 20133 Milan, Italy
³ IASF-CNR, Sezione di Bologna, via Gobetti 101, Bologna, Italy
⁴ Università degli Studi di Milano, via Celoria 16, 20133 Milan, Italy
⁵ University of California at Santa Barbara, Physics Department, Santa Barbara, CA 93106, USA

Corresponding author: A. Mennella, daniele@mi.iasf.cnr.it

Received: 11 March 2002
Accepted: 7 June 2002

Abstract

We use an analytic approach to study the susceptibility of the Planck Low Frequency Instrument radiometers to various systematic effects. We examine the effects of fluctuations in amplifier gain, in amplifier noise temperature and in the reference load temperature. We also study the effect of imperfect gain modulation, non-ideal matching of radiometer parameters, imperfect isolation in the two legs of the radiometer and back-end noise. We find that with proper gain modulation gain fluctuations are suppressed, leaving fluctuations in amplifier noise temperature as the main source of noise. We estimate that with a gain modulation factor within of its ideal value the overall knee frequency will be relatively small (<0.1 Hz).