A CMOS sinusoidal signal generator based on mixed-time processing for electrical bioimpedance spectroscopy supporting beta dispersion range

A CMOS sinusoidal signal generator based on discrete-time (DT) and continuous-time (CT) processing is proposed for electrical bioimpedance spectroscopy supporting beta dispersion range of tissues. Differential stepwise sine-like signals with oversampling ratio (OSR) of 16 are used for input signals. DT filters with OSR=16 are used to attenuate close-in harmonics of these input signals, and a CT transconductance-C low-pass filter is used to attenuate less suppressed high-order harmonics under the DT processing of OSR=16. This proposed signal generator designed in a 0.25μm CMOS process supports frequency range from 1 kHz to 2.048 MHz. The spurious-free dynamic range more than 65.7 dB and the total harmonic distortion less than 51.6m% were achieved for about 550-mVpp output amplitude.