Area efficient low power neural amplifiers using MOS and MIM capacitors in submicron technologies for ultra low corner frequencies

This paper presents the design methods that allow to drastically limit an area of a recording channel in multichannel integrated circuits dedicated to neurobiology experiments. The techniques that are presented in this paper allow to apply them in a 3D pixel multichannel integrated systems where area limitations are very strict. Furthermore, these allow one to minimize main problems existing in modern submicron processes i.e. leakage currents, an ability of obtaining very large MOS based resistances or a uniformity of main parameters of recording channels. For further improvement of the recording channels we designed and processed in a 180nm CMOS technology two recording channels that differ from one other in channel feedback components. The measurement results show that our methods allow to tune the lower cut-off frequency in a very large range, i.e. 10 mHz-300 Hz. The upper cut-off frequency can be changed into two different modes, i.e. neural spike recording mode where it is equal to 9 kHz or slow biomedical signals recording mode where it can be changed in the 10 Hz - 280 Hz range. The voltage gain of the recording channels can be switched either to 260 V/V or to 1000 V/V. The input referred noise of the recording channel is equal to 5 μV while its power consumption is equal to only 11 μW. The single recording channel occupies only 0.06 mm² of the chip area and together with its large functionality allows one to adapt it into modern 3D pixel multichannel neurobiology applications.