Tunable Compact Low-Noise Amplifier With Permalloy Thin-Film Enabled Slow-Wave Transmission Lines

This paper provides a first tunable low-noise amplifier (LNA) design with Permalloy (Py) enabled inductors. Tunable inductor is an important passive device in adaptive radio frequency circuit design. In this paper, a new integrated tunable inductor is implemented utilizing novel slow-wave transmission lines that are built with coplanar waveguide having alternative high and low impedance signal sections, and the Py thin films are deposited and patterned on the signal line of narrow section to provide higher and tunable inductance density. The inductance per unit length has been increased from 877 to 949 nH/m with 100 nm Py thin film at 5 GHz. A tunable 5 GHz LNA utilizing SWLTs is developed, where the tunability of power reflection and power gain of LNA are demonstrated with variable inductors.