Assessing the Power Efficiency of MEMS Audio Transducers
Recent studies show that wireless earbud users are demanding more innovations and comfort, improved battery life and other things that go beyond sound quality. More innovations require further functional integration and additional requirements on the tight power budget. Basically, all MEMS speakers aspiring to the micro speaker market for earbuds and hearables claim to be more power efficient than moving coil speakers. From the electrical engineering point of view, these MEMS transducers are capacitors. This means that the reactive power doubles when the frequency doubles, it quadruples when the voltage doubles. In this contribution, we want to discuss some fundamental relations of converting an electrical input to an acoustic output and the implications for a proper transducer design that is necessary to deliver on the promise of power efficiency.