Wideband low-power current-feedback instrumentation amplifiers for bioelectrical signals

In most bioelectrical acquisition systems, there is the need for amplifying small differential voltages. This paper describes a CMOS instrumentation amplifier (IA) based on the principle of current feedback for use in biological tissue characterization by bioelectrical impedance measurement. The constraints on the design of IA´s for wideband operation are addressed. An approach that can be exploited to design a wideband current-feedback IA will be examined. To verify the feasibility of the proposed approach, an IA was designed in 0.35 μm CMOS technology for use in the frequency range from 100 Hz to 4 MHz. The designed IA dissipates 240 μW from a single 2-V power supply. Post-layout simulation results are provided and the corresponding performance is discussed.