A 470μA direct readout circuit for electret and MEMS digital microphones

A direct readout circuit configurable for electret or MEMS digital microphones is presented. The circuit includes a transducer interface, a programmable preamplifier, a 4 th order ΣΔ modulator, a bandgap reference, a clock detection circuit, and a stability recovery system. A prototype has been realized in a 0.25μm CMOS process, performing 63dBA SINAD at 1Pa, and a consumption of 470μA at 1.6V supply voltage.