A 0.8V, 7μA, rail-to-rail input/output, constant Gm operational amplifier in standard digital 0.18μm CMOS

A two-stage amplifier, operational at 0.8V and drawing 7/spl mu/A, has been integrated in a standard digital 0.18/spl mu/m CMOS process. Rail-to-rail operations at the input are enabled by complementary transistor pairs with g/sub m/ control. The efficient rail-to-rail output stage is biased in class AB. The measured DC gain of the amplifier is 75dB, and the unity-gain frequency is 870kHz with a 12pF, 100k/spl Omega/load. Both input and output stage transistors are biased in weak inversion

A compact CMOS MEMS microphone with 66dB SNR

A microphone system, comprising two differentially-operated MEMS microphones and a CMOS differential amplifier mounted on a common die substrate, has a very small volume of 2.6x3.2x0.865mm3, showing a record-high SNR of 66dB over the 20Hz-20kHz audio band. The system sensitivity is -33.5dB (Vrms/Pa), PSRR is above 55dB, and THD is below 1% for sound pressure levels below 112dB. The current consumption is 120μA from a 1.8V power supply