Current biased pseudo-resistor for implantable neural signal recording applications

A current biased pseudo-resistor for implantable extracellular neural signal recording applications is introduced in this work. The pseudo-resistor, which is biased in the subthreshold region, is able to realize a very large resistance while keeping the silicon area small. A wide range of resistances can also be implemented by changing the bias current. Issues concerning the linearity of the pseudo-resistor and the frequency response of the pseudo-resistor bias are discussed in this paper. The chips were fabricated in a 0.5 micron 3M2P CMOS process and the test results show that the current biasing method is able to realize more reliable resistance than the voltage biasing method.