A 350-nW Low-Noise Amplifier With Reduced Flicker-Noise for Bio-Signal Acquisition

For the acquisition of bio-signals, like EEG or ECG, there is a need for low-noise amplifiers that are capable of amplifying input-signals with high source-impedance at very low frequencies 100mV at the electrode-tissue interface, ideally without using external components. This fully differential amplifier achieves a gain of 38.7 dB with a CMRR of 74 dB and an input-referred noise of 0.97 $\mu\mathrm{V}_{\mathrm{rms}}$ while consuming 350 nW of power at 1V supply voltage. This renders the amplifier well suited for RF-powered wireless bio-sensing applications. The amplifier uses a flicker-noise reducing switched capacitor feedback and a special method of metal-metal capacitor design to maximize the area-density. This fully-integrated design is implemented in a 1P6M180 nm CMOS technology using 0.42mm2.