Design of current mode instrumentation amplifier for portable biosignal acquisition system

This paper describes the design of current mode instrumentation amplifier (CMIA) for portable biosignal acquisition system. The CMIA topology is based on voltage mode operational amplifier (op amp) power supply current sensing technique. Op amp mismatch and precise current mirrors are two design challenges of this topology. A simulation analysis is conducted based on an implementation in a CMOS 0.35 ¿m technology. The CMIA consumes 20.22 ¿W under a 3 V DC power supply and has a continuous adjustable gain bandwidth product (GBW)-independent voltage gain via single resistor. The CMRR is higher than 120 dB up to 1 Hz and more than 80 dB up to 100 Hz.