A CMOS multi-sine signal generator for multi-frequency bioimpedance measurements

Multi-frequency signals are important for a variety of sensing and instrumentation applications. These include various impedimetric applications inhibiting a time-varying behavior, where a system has to be characterized rapidly across a specific bandwidth. In this paper a novel CMOS system is presented, which can generate a multi-sine signal with components of any desired frequency and amplitude, while generating at the same time the required 0° and 90° demodulation signals necessary at each frequency for a synchronous demodulation front-end. The proposed system performs summing of waveforms of different frequencies in the current domain, eliminating the need for an additional summing amplifier.