A Wideband Tunable, Nonreciprocal Bandpass Filter Using Magnetostatic Surface Waves with Zero Static Power Consumption

TL;DR

This paper introduces a compact, tunable, nonreciprocal bandpass filter operating between 4-17.7 GHz, utilizing magnetostatic surface waves in YIG waveguides with zero static power, suitable for modern wireless RF front-ends.

Contribution

It presents a novel miniature filter design with wideband tunability, high nonreciprocity, and zero static power consumption using a thick YIG film and a unique biasing circuit.

Findings

Achieves >25 dB nonreciprocity and 4-17.7 GHz tunability.

Demonstrates low insertion loss (3-5 dB) and high out-of-band rejection (>30 dB).

Operates with high linearity and power handling capabilities.

Abstract

Modern wireless systems demand compact, power-efficient RF front-end components that support wideband tunability and nonreciprocity. We present a new class of miniature bandpass filter that achieves both continuously tunable frequency operation (4-17.7 GHz) and high nonreciprocity (>25 dB), all within a compact size of 1.07 cm3. The filter employs a microfabricated 18 micrometer thick Yttrium Iron Garnet waveguide with meander-line aluminum transducers, enabling low-loss unidirectional propagation via magnetostatic surface waves. Leveraging a benzocyclobutene planarization fabrication process, this study enables a dispersion profile unique to thick YIG films, resulting in enhanced filter skirt performance with minimal spurious modes. Frequency tuning is enabled by a zero-static-power magnetic bias circuit using transient current pulses, eliminating continuous power consumption. The filter demonstrates low insertion loss (3-5 dB), high out-of-band rejection (>30 dB), narrow bandwidth (100-200 MHz), robust power handling (>10.4 dBm), and high linearity (IIP3 > 26 dBm).