Transmitter self-calibration of time delay and frequency response for high baud-rate QAM transceivers

US9991953B1 · kind B1 · utility

Assignee

• Cisco Technology, Inc. · US

Inventors

• Christopher Fludger · Nuremberg, DE
• Thomas Duthel · Nuremberg, DE

Key dates

• Filing date: Jan 5, 2017
• Grant date: Jun 5, 2018
• Expiry date: Jan 5, 2037

Classification

• Technology area (CPC H): Electricity
• CPC primary: H04B10/541
• WIPO field: Telecommunications
• WIPO sector: Electrical engineering

Abstract

A self-calibration procedure for an optical transmitter is provided. During the self-calibration procedure, a phase bias of an optical modulator of the optical transmitter is set so that an in-phase path and a quadrature path of the optical modulator are in phase. Stimulus signals are supplied to the in-phase and quadrature paths of the optical modulator, over a frequency range. Detection, with a photodetector, is made of an optical output of the optical modulator at a plurality of frequency steps over the frequency range. A photodetector converts an optical output of the optical modulator to an electrical signal. First and second measurement values are generated from the electrical signal output from the photodetector. A frequency spectrum and/or time delay is computed from the first and second measurement values for each frequency step value over the frequency range.