Extremely Low-Power Fifth-Order Low-Pass Butterworth Filter

A fifth-order Butterworth low-pass filter using multiple-input operational transconductance amplifiers (OTAs) is proposed in this paper. It is expressed that the number of OTAs that used for realizing fifth-order low-pass filter can be reduced using multiple-input OTA and results to decrease the power consumption and the active area. N-input OTA can be obtained using multiple-input bulk-driven quasi-floating gate technique. Subthreshold technique is used to achieve extremely low power consumption which can be applied to biomedical systems. The proposed topology is simulated using 0.18 $\mu \text{m}$ standard CMOS process. Simulation results show that the proposed filter has a bandwidth located within 250 Hz, a power consumption of 41 nW and a dynamic range of 61 dB.