A 2 × 2 Neural Amplifier Macro-Pixel with Shared DC Servo Loop for High-Density Brain-Computer Interfaces

Brain-computer interfaces of the future will be recorded from tens of thousands of high-density electrodes. This paper presents a neural amplifier for next-generation single-cell resolution BCIs. The amplifier leverages spatial signal correlation to introduce a novel shared DC servo loop to improve area efficiency while maintaining state-of-the-art power efficiency. Post-layout simulations in 40 nm CMOS technology achieve a $\mathbf{5 0} \mathrm{dB}$ gain in a $[0.1-5.2] \mathrm{kHz}$ bandwidth. The amplifier consumes 920 nW and achieves a total input-referred noise of $8 \mu \mathrm{~V}_{\text {rms}}$ while occupying only $35 \mu \mathrm{~m} \times 35 \mu \mathrm{~m}$ per recording channel.