A 55nm Cascode Flipped Voltage Follower for MEMS Microphone Interfaces.

Audio sensors systems scaling leads to microphone interfaces built in deep sub-micron technologies, which introduces critical aspects in high performance analog cells design. In this paper a Cascode Flipped Voltage Follower interface for Micro Electro-Mechanical System (MEMS) silicon microphones is presented. The pseudo-differential interface architecture suits differential microphones, gaining in linearity performance due to symmetry properties of the system. The device is based on the cascode flipped voltage follower, which allows minimizing chip area and power consumption, while enhancing noise and distortion. A prototype in 55nm CMOS features an A-weighted output integrated noise in audio frequency range of -112 dBV(A) and an Acoustic Overload Point (AOP) of 133dB(spl). Power consumption is lower than 225 mu W from a 1.5 V voltage supply.