AM to PM conversion of linear filters

TL;DR

This paper analyzes how linear filters convert amplitude modulation to phase modulation and vice versa, providing models, evaluations, and guidelines for maintaining AM and PM isolation in signal processing.

Contribution

It introduces a detailed model for AM to PM conversion in linear filters, including a scatter model and evaluation functions based on the filter's transfer function.

Findings

The model accurately predicts AM to PM conversion behavior.

System bandwidth significantly affects AM and PM isolation.

Practical rules of thumb are developed for system design.

Abstract

The conversion between amplitude modulation and phase modulation as a modulated signal goes thrugh a filter is analyzed. The difference in how the modulated sideband ampitude experience the filter, and how AM and PM has opposite signs for one of their sidebands interact. The conversion between AM and PM is modelled, providing a scatter model and evaluation of two functions based on the linear filters transfer function. The system bandwidth effects is analyzed and rule of thumb developed to ensure AM and PM isolation.