This brief presents a differential difference amplifier (DDA) with a pseudo-differential (PD) common-mode feedback (CMFB) for neural signal recording. One of the input transconductors within the proposed DDA is connected… Click to show full abstract
This brief presents a differential difference amplifier (DDA) with a pseudo-differential (PD) common-mode feedback (CMFB) for neural signal recording. One of the input transconductors within the proposed DDA is connected to target neural signal, to ensure a high input impedance. Another input transconductor employs a self-stabilized topology to stabilize the dc quiescent point and to determine the cut-off frequency. The CMFB is applied via the proposed PD terminal. Benefiting from the parallel connection of PD, the common mode rejection ratio (CMRR) is approximately increased by a factor of differential-mode gain, without damaging the voltage headroom and dynamic range. Moreover, the proposed PD CMFB is suitable for multi-channel neural signal acquisition, the more the channels, the higher the CMRR. The circuits are targeted at IC realization, designed in a 0.18-
               
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