Current-conveyor-based wide-band current driver for electrical impedance tomography

摘要

Objective: In this paper a wide-band integrated current driver for electrical impedance tomography (EIT) is presented. The application is primarily for prostate and breast cancer detection which require the tissue to be interrogated at frequencies up to 10 MHz while achieving low harmonic distortion and high accuracy. Approach: The current driver is based on current conveyor architecture and can deliver 1.2 mA of peak to peak ac current between frequencies of 100 Hz–10 MHz. It is fabricated in CMOS 0.18 μm technology with a power supply of 3.3 V, and occupies a core area of 0.26 mm2. Main results: The measured harmonic distortion for a peak current of 1.2 mA is <0.1% for frequencies less than 100 kHz, and increases to 0.68% at 10 MHz. The measured output impedance of the current driver is 101 k at 1 MHz and 19.5 k at 10 MHz. Significance: The circuit is suitable for high frequency active electrode applications.