CMRR improvement for multichannel integrated recording circuits processed in submicron technologies dedicated to neurobiology experiments

This paper presents Common Mode Rejection Ratio´s (CMRR) measurement results of a multichannel integrated circuit dedicated to the recording neurobiological signals and shows the design method that allows for CMRR improvement in multichannel architectures. A 64-channel Neuro-Stimulation-Recording chip named NRS64 is processed in CMOS 180nm technology. The measurements are followed by the detailed analysis of effects that may cause a CMRR deterioration. The simulation results of these effects are also presented and discussed. Additionally, the method improving the CMRR is presented that allows to increase both the CMRR and its uniformity from channel to channel. Furthermore, the design of a prototype multichannel integrated circuit is presented where proposed method was applied. The chip was designed in a 180nm CMOS process.