A tunable bandwidth 6th-order active low-pass filter in 0.18 um CMOS technology

Abstract

In this paper, a tunable bandwidth 6th-order active Butterworth low-pass filter has been designed in 0.18 um UMC CMOS technology. The topology consists of three second-order filters designed by using the Sallen-Key topology. The standard two-stage operation amplifier with Miller compensation capacitor is utilized as an operation amplifier stage in 2nd-order Butterworth low-pass filter. The cutoff frequency (3dB bandwidth) can be adjusted from 22 kHz to 52 kHz with a step value of 10 kHz by using a programmable capacitor bank. The post-layout simulation results show that for each cutoff frequency value, the designed tunable low-pass filter has a maximum passband attenuation of 11.53 mdB and a minimum stopband attenuation of 50 dB. The power consumption of designed active filter is 2.24 mW for a 1.8 V power supply. It achieves an in-band integrated input-referred noise of 130.502 uVrms and occupies active area of 0.65 mm2