Dual mode 4th order active-RC low-pass filter with tunable cut-off frequency from 3 MHz to 20 MHz in 65 nm CMOS

Abstract

In this paper, a 4 th order active-RC filter with two approximation modes and a tunable bandwidth from 3 MHz to 20 MHz is presented. The filter can be configured to achieve maximally flat in-band magnitude or phase response by using a dual mode resistor bank and h as gain control. PVT induced parameter drift compensation is accomplished by using a reduced-in-size resistor bank structure made of series and parallel connected resistors. Furthermore, a, design method for the resistor bank is presented, that allows component value calculation based on a ccuracy and tuning step requirements. The power dissipation is bandwidth depended and ranges from 13 mW to 23 mW from a 1.2 V supply for the entire tuning range, while the SFDR is higher than 72 dB and 65 dB at min and max bandwidth settings respectively. The proposed filter is designed and its parameters verified by using 65 nm CMOS technology and occupy a layout area of 0.172mm 2.