PAPER SESSION 1: INTEGRATION PERSPECTIVES
A Fully Differential Digital Input Class D with EMI
Spreading Method for Mobile Application
Cellier(1,3), Emmanuel Allier(1), Carlo Crippa(2), Rossella
Bassoli(2), Gael Pillonnet(3), Angelo Nagari(1), Nacer
(1) ST Ericsson, Grenoble, France.
(2) ST Ericsson, Agrate, Italy.
(3) Institut des Nanotechnologie de Lyon (INL) – CPE
Lyon, Lyon, France.
Class D audio amplifiers are widely used in embedded
systems to achieve high efficiency. Digital class
D accepts bit stream as input signal to drive loudspeakers.
Major drawbacks of such systems are the
nonlinearity due to the switched behavior and EMI
radiations issued from the output low pass filter. This
paper presents a digital class D amplifier with a local
analog feedback loop to improve performances of the
power stage and digital method to spread output
spectrum in order to reduce EMI radiation. The amplifier,
including digital modulator and analog power
stage, was integrated in a single chip in 0.13 ìm
CMOS technology. The silicon results confirm the
validity of the theoretical analysis.