Nikolaos Gkouvatsos, "Design of low-power low-noise integrated CMOS biosignal amplifier", Diploma Work, School of Electrical and Computer Engineering, Technical University of Crete, Chania, Greece, 2020
https://doi.org/10.26233/heallink.tuc.87060
In this work we will study the designing procedure of a low-power low-noise amplifier, with application in brain signals amplification. The bio-amplifier was implemented in a 90 nm CMOS process so that it is suitable for integration into multichannel recording implants. The recording electrode of the bio-amplifier is directly connected to the input of a low-noise amplifier which includes a Miller integrator in its feedback. The integrator, achieving a long time constant, gives the bio-amplifier the ability to reject unwanted low frequency signals as it sets its low cut-off frequency at 121.5 Hz. The large time constant of the integrator results from a structure of diode-connected transistors which employs a high resistance and allows the use of capacitors of reduced capacitance and area. The design of the amplifier under the constraints resulting from the low supply voltage of 90 nm technology, 1.2 V, was done with the inversion coefficient methodology (IC) that allows design in weak, moderate and strong inversion. The midband gain of the amplifier is 46.8 dB, its bandwidth is 10.84 kHz, the noise at the input 5.8 μVrms and the power dissipation 8.4 μW.