A Review of Design Methods for Digital Modulators

One of the main components in a digital class D amplifier is the digital modulator. This modulator is necessary so that an N-bit digital input can be converted into 1-bit modulated pulses, which in turn are used for high efficiency operation in the output stage of the class D amplifier. In this paper, we review three design methods for digital modulators. The three design methods are: pulse width modulation, pulse density modulation, and algorithmic PWM-multi-bit DeltaSigma modulation. Among these methods, the algorithmic PM-multi-bit DeltaSigma modulation can have the best trade-offs between performance and power dissipation.