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This paper reports a novel application of finite horizon constrained optimization techniques to design an audio-band full digital amplifier. The digital amplifier using power MOSFET requires a modulator to modulate the reference signal into binary sequences. The modulator can be viewed as an over-sampled quantizer with noise-shaping requirement. An FPGA (field programmable gate array) implementation of the finite horizon constrained optimization technique to construct the modulator is presented. Experimental results are shown by driving the loudspeaker load.

This paper proposes a novel switch-mode power stage architecture for actuator array. When the number of actuator is large, the associated power amplifier becomes costly and bulky if each actuator is controlled by an independent amplifier. Further, the increased operational block raises power consumption and is inefficient. The proposed architecture allows sharing of the power amplifier among actuators, and thereby reducing the number of switching devices. The switching method is controlled by an MIMO optimal feedback quantization, which is designed to minimize a weighted measure of the quantization distortion. The proposed method is applied to design a class-D stereo audio amplifier (dual actuators). The control performance and cross-talk behavior are investigated.