Bioimpedance measurements are performed in a va-udriety of medical applications including cancer detection in tissue. Such applications require wideband (typically 1 MHz) accurate ac current drivers with high output impedance and low distortion. This paper presents an integrated current driver that fulfills these requirements. The circuit uses negative feedback to accurately set the output current amplitude into the load. It was fabricated in a 0.35- μm complementary metal–oxide–semiconductor (CMOS) process technology, occupies a core area of 0.4 mm, and operatesudfrom ±2.5-V power supplies. For a maximum output current ofud1mA p-p, the measured total harmonic distortion is below 0.1%,udand the variability of the output current with respect to the loadudis below 0.5% up to 800 kHz increasing to 0.86% at 1 MHz. Theudcurrent driver was tested for the detection of cancer sites from postoperative human colon specimens. The circuit is intended for use in active electrode applications.
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