Frequency Tunable Magnetostatic Wave Filters With Zero Static Power Magnetic Biasing Circuitry

TL;DR

This paper presents a miniature, zero static power magnetostatic wave filter with wide tunability from 3.4 GHz to 11.1 GHz, suitable for mobile RF applications, achieved through innovative magnetic biasing and micromachined resonant cavities.

Contribution

It introduces a novel zero static power, tunable MSW filter using a nonvolatile magnetic bias assembly and micromachined YIG cavities, reducing size and power consumption compared to electromagnet-based designs.

Findings

Achieved continuous frequency tuning from 3.4 GHz to 11.1 GHz.

Maintained low insertion loss of 3.2 to 5.1 dB.

Provided high linearity with input intercept point >41 dBm.

Abstract

A single tunable filter simplifies complexity, reduces insertion loss, and minimizes size compared to frequency switchable filter banks commonly used for radio frequency (RF) band selection. Magnetostatic wave (MSW) filters stand out for their wide, continuous frequency tuning and high-quality factor. However, MSW filters employing electromagnets for tuning consume excessive power and space, unsuitable for consumer wireless applications. Here, we demonstrate miniature and high selectivity MSW tunable filters with zero static power consumption, occupying less than 2 cc. The center frequency is continuously tunable from 3.4 GHz to 11.1 GHz via current pulses of sub-millisecond duration applied to a small and nonvolatile magnetic bias assembly. This assembly is limited in the area over which it can achieve a large and uniform magnetic field, necessitating filters realized from small resonant cavities micromachined in thin films of Yttrium Iron Garnet. Filter insertion loss of 3.2 dB to 5.1 dB and out-of-band third order input intercept point greater than 41 dBm are achieved. The filter's broad frequency range, compact size, low insertion loss, high out-of-band linearity, and zero static power consumption are essential for protecting RF transceivers and antennas from interference, thus facilitating their use in mobile applications like IoT and 6G networks.