High-Output Impedance CMOS Current Conveyor Driver design for Chest Electrical Impedance Tomography

Electrical Impedance Tomography is a medical image modality in which the body tissues are excited by external electrical currents and the resulting image represents impedance properties within the body. The current driver is one of the main blocks of an EIT system, responsible to generate the output current to the body through the electrodes. Therefore, sinusoidal current driver is desired that has a low distortion and a high output impedance, to assure the integrity of the signal in the tissue. The proposed circuit is based on a second generation current conveyor architecture with a triple cascode gain boost to increase the output impedance. The current driver was designed consuming 7.2 mW, operating at ± 1.65V in 180 nm technology, with 605 $\mathrm{k}\Omega$ of output impedance, at 1 MHz, and 2 mA output current with total harmonic distortion <1%. The core of the current driver occupies a total core area of 0.006 $\mathrm{m}\mathrm{m}^{2}$ without pads and 0.08 $\mathrm{m}\mathrm{m}^{2}$ with pads.