Noise analysis of a driven chain with an improved Howland current source for electrical impedance tomography

Abstract Driven chains, also called current injection blocks, are one of the main sub-blocks of electrical impedance tomography (EIT) systems. In most applications, the noise performance of a driven chain is a critical figure of merit, which limits the signal-to-noise ratio of an EIT system. Accurate noise analysis of driven chains with improved Howland circuits is still missing in the EIT literature. In this paper, an accurate noise model of a driven chain with an improved Howland current source for an EIT system is presented. Both simulated and lab-built driven-chain circuits are employed to validate our model. It is shown that the simulation and test results closely match. This work provides both an accurate noise model and a noise budget method for EIT driven chains with an improved Howland current source.