Floating voltage-controlled current sources for electrical impedance tomography

The design of a current source for wideband electrical impedance tomography medical instrumentation is a challenging task. This paper describes two simple OTA-based floating voltage-controlled current sources (VCCSs) for this application. Both designs are suitable for VLSI implementation and overcome the drawbacks of existing opamp-based discrete VCCS designs. The floating VCCSs are designed to drive loads of 100 Omega to 2 kOmega with current amplitudes of up to 500 muA. The working frequency band is between 100 Hz to 1 MHz. Simulated results using a 0.35-mum CMOS process technology are presented to show the operation of the circuits.