2025/06/11 by Ankitha E. Bangera, Bangera, Ankitha E · 1 citation
Engineering · Physics and Astronomy · #Advanced Optical Sensing Technologies #Advanced Semiconductor Detectors and Materials #Applied Physics (physics.app-ph) #FOS: Computer and information sciences #FOS: Electrical engineering #FOS: Physical sciences #Information Theory (cs.IT) #Instrumentation and Detectors (physics.ins-det) #Radiation Detection and Scintillator Technologies #Signal Processing (eess.SP) #electronic engineering #information engineering
paper · pdf · doi:10.48550/arxiv.2506.09900
openalex publication_date 2025/06/11 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The signal-to-noise ratio of a multistage cascade network is often estimated using the well-known Friis' formulas for noise factors (or the noise figures in decibels). However, this article addresses the major errors in Friis' noise factor formulas for higher stages. Additionally, we re-derive the correct formulas to calculate the stage-wise noise factors for cascade networks from the basic definition of noise factors. We then present a comparison of our derived formulas with Friis' noise factor formulas. Contrary to Friis' formula, we define the total noise factor of an n-stage cascade network as the product of its stage-wise noise factors. We further validate our derived formulas for a cascade network by correlating them with the expressions for a staircase avalanche photodiode.