Active Inductor-Based Ultra-Wideband Low Noise Amplifier for Rejection of Wireless LAN Interference

Abstract

This paper presents a low noise amplifier (LNA) for the ultra-wideband (UWB) application in the range 3.1–10.6 GHz based on active inductor topology. The LNA is designed to provide a flat gain and to reject wireless local area networking interference at 5–6 GHz band. An active inductor based on the feedback resistor topology is proposed in this work and integrated with the LNA. The use of an active inductor instead of a conventional CMOS spiral inductor provides advantages over the area, quality factor, and inductance. The active inductor provides a relatively uniform inductance at 5–6 GHz and is used to design an on-chip notch filter circuit, which achieves a maximum attenuation of 45 dB at the center frequency of ~5.6 GHz. The LNA is designed and processed in the standard 0.18 mm CMOS technology. The simulated LNA exhibits the gain of 20 dB and a noise figure of less than 3.7 dB in the non-interfering bands. The input (S11) and output return losses (S22) are less than –10 and –12 dB, respectively, in the allocated UWB frequency spectrum, and amplifier occupies a chip area of 0.54 µm2. The proposed LNA has a superior flat gain, excellent interference rejection, minimum return losses, and a low noise figure in the intended operation band. This LNA finds important application in the radiofrequency front-end devices for UWB application.