A chip design for body composition analyzer

This paper describes a chip design technique for body composition analyzer based on the BIA (bioelectrical impedance analysis) method. All the functions of signal forcing circuits to the body, signal detecting circuits from the body, Micom, SRAM and EEPROMs are integrated in one chip. Especially, multi-frequency detecting method can be applied with selective band pass filter (BPF), which is designed in weak inversion region for low power consumption. In addition, new full wave rectifier (FWR) is also proposed with differential difference amplifier (DDA) for high performance (small die area, low power consumption, rail-to-rail swing). The prototype chip was implemented with 0.35 mum CMOS technology and shows the power dissipation of 6 mW at the supply voltage of 3.3V. The die area of prototype chip is 5 mm times 5 mm.