Elimination of 3D parasitic effects on microphone power supply rejection

摘要

A MEMS microphone package is described that includes a first node and a second node having nearly equivalent 3D parasitic capacitances relative to a preamplifier of the microphone package, such that any noise generated on the first node is equivalent to any noise generated on the second node. An external power supply is connected to the first node and provides a bias voltage signal to the MEMS microphone package via the first node. An inverting amplifier is connected between the power supply and the second node. A third node is connected to the first node through a packaging parasitic capacitor, while the second node is connected to the third node through either an intended parasitic capacitor or an explicit capacitor. The noise coupled from the external power supply to the third node is then cancelled by summing the inverted power supply noise into the third node.