Ladder-Based Synthesis and Design of Low-Frequency Buffer-Based CMOS Filters

Buffer-based CMOS filters are maximally simplified circuits containing as few transistors possible. Their applications, among others, include nano to micro watt biomedical sensors that process physiological signals of frequencies from 0.01 Hz about 3 kHz. The order a buffer-based filter is not greater than two. Hence, obtain higher-order filters, cascade second-order constructed. In this paper, more general method for synthesis developed and presented. uses RLC ladder prototypes arbitrary orders. addition, set novel circuit solutions with ultra-low voltage power proposed. introduced were synthesized simulated using 180-nm technology X-FAB. One the designed fourth-order, low-pass features: 100-Hz passband, 0.4-V supply voltage, consumption less 5 nW, dynamic range above 60 dB. Moreover, total capacitance proposed (31 pF) 25% lower compared structure conventional (40 pF).