A Low-power Third-Order Butterworth Filter for NB-IoT Application

This paper presents a third-order Active-RC filter for NB-IoT applications. The filter achieves relatively low power with power-efficient feedforward-compensated OTA. Digital-controlled resistors and capacitor arrays are flexible for gain and bandwidth tuning. The chip is fabricated in SMIC 55nm CMOS process, occupies an area of 0.19mm 2 . The measurement results indicate that the filter provides 3MHz tuning range and achieves an IIP3 of 28.9dBm with 1.2V power supply and the power consumption is 1.96mW.