Design of a bioimpedance measurement system using direct carrier compensation

Operation principles, modeling and practical design of a novel system for bioimpedance measurement are introduced is this paper. The system is based on direct compensation of the carrier of response signal in order to emphasize variations of it; amplitude and phase, both caused by a biomodulation in living tissue. The proposed system is qualified to demodulate the biomodulated signals with the modulation depth as low as 0.1 to 1%, considering an excitation in the frequency range from 1 kHz to 1 MHz. The multichannel measurement system is designed for monitoring and diagnosing of the cardiovascular system.