Digital I/Q modulator having a predistortion

US7158582B2 · kind B2 · utility

Assignee

• Fraunhofer-Gesellschaft zur förderung der angewandten Forschung e.V. · DE

Inventors

• Eberhard Gamm · Ebermannstadt, DE
• Reiner Retkowski · Erlangen, DE
• Gerald Ulbricht · Westerburg, DE
• Heinz Gerhaeuser · Erlangen, DE

Key dates

• Filing date: Mar 2, 2001
• Grant date: Jan 2, 2007
• Expiry date: Jun 25, 2023

Classification

• Technology area (CPC H): Electricity
• CPC primary: H04L27/368
• WIPO field: Digital communication
• WIPO sector: Electrical engineering

Abstract

An I/Q modulator processes a time-discrete I/Q signal comprising an I component and a Q component. The I/Q signal is based on a sampling frequency which is equal to four times a carrier frequency of a carrier signal onto which the I/Q signal is modulated. A predistorter of the modulator predistort the I and components with a predistortion signal, which depends on the I and Q components, so as to form a predistorted I component and, in temporal alternation therewith, a predistorted Q components. An adjuster of the modulator adjusts the signs of the predistorted I and Q components so that two temporally successive predistorted components have a first sign and two additional successive predistorted components, which follow the first-mentioned components in time, have a second sign which is the inverse of the first sign, so as to produce therefrom an output signal at an output of the modulator.