A Chopper Stabilized, Current Feedback, Neural Recording Amplifier

Advanced neural prosthetics require high-density neural recording and stimulation electrodes interfacing with the tissue. For an implantable device, area, power consumption, and noise performance are the key design metrics. Due to the low-frequency nature of the recorded signals, a chopping technique is inevitable to satisfy the noise requirement while maintaining a small area and low-power consumption. However, chopping leads to a significant drop in input impedance, which leads to potential attenuation of neural signals recorded from high-impedance miniature electrodes, and an unacceptable large input current drawn from the tissue. This letter presents a chopper stabilized, current feedback amplifier (CFA) with input impedance boosted to 3.0 GΩ. The amplifier has an adjustable voltage gain of 40-60 dB, and an adjustable high-pass cut-off frequency of 0.5-5 Hz, with a power consumption of 2.6 μW and noise efficiency factor (NEF) of 3.2.