| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a method of linearizing characteristics of a class-D power output stage by compensating a pulse area error caused by a non-constant power supply and the inconsistency of a similar circuit. <P>SOLUTION: A class-D amplifier typically converts a PDM (pulse density modulated) input signal using a Sigma Delta modulator 21, and typically uses an H-bridge 24 as the class-D power output stage. A basic idea is to keep the time-voltage area of each pulse constant. To obtain this, a circuit applies integration 22 to the power supply voltage, and the integration is started with the PDM input pulse 23 and is stopped when reaching a defined time voltage reference. To compensate voltage drops of both ends of output devices in addition to power supply variations for example, an input for an integrator is refered to actual voltages of both ends of the output load 25 more directly. <P>COPYRIGHT: (C)2004,JPO&NCIPI</p> |
