2.4 GHz CMOS bandpass filter using active transmission line

Abstract

A bandpasss filter (BPF) using active transmission lines (ATLs) in a standard 0.18 μm CMOS technology at the 2.4 GHz band is presented. The ATL consists of a passive transmission line which is loaded by Λ-type circuits periodically. The ATL incorporating the Λ-type circuits not only compensates its resistive losses but also increases the slow-wave factors. Moreover, an inductor is also used in the BPF to improve the passband flatness and circuit instability. Under a power consumption of 21 mW, the BPF achieves 0.5 dB insertion loss at the centre frequency of 2.3 GHz, and a 3 dB bandwidth of 550 MHz.