Patent ID: 7336794
Filing Date: 2008-02-26
Classification: H04R

Abstract:
1. A miniature loudspeaker assembly comprising: a loudspeaker casing made in an EMI shielding material, the loudspeaker casing comprising: a digital interface adapted to receive a digital input signal, a three-level sigma-delta modulator adapted to receive the digital input signal and provide a three-level PDM signal, a correction circuit comprising a filter adapted to convert the three-level PDM signal into a pattern of pulses with five or more states, a pattern generator adapted to convert the pattern of pulses into a pattern of pulses with level dependent RTZ states, and a loudspeaker comprising a motor adapted to receive the pattern of pulses with level dependent RTZ states, the motor further being adapted to drive a diaphragm so as to generate an acoustical signal.