A Low Power, Low THD Current Driver with Discrete Common-Mode Feedback for EIT Applications

A low THD sinusoidal current driver for electrical impedance tomography (EIT) applications is proposed and analyzed in this paper. A discrete common-mode feedback method is proposed to increase the accuracy of the output current amplitude and output impedance. The current driver is designed in 65 nm technology under 3.3 V supply with a chip area of 0.0843 mm
²
, The maximum output current amplitude is 1.2 mA. In simulations the current driver achieves an average THD of 0.098% at 1 mA output current amplitude and 500 kHz output current frequency. The simulated output impedance is higher than 4
$\mathbf{M}\Omega$
at a load impedance lower than 3.5
$\mathbf{k}\Omega$
. The current consumption of the circuit is 1.47 mA and provides a current efficiency of 81.6%.