A wideband tunable, nonreciprocal bandpass filter using magnetostatic surface waves with zero static power consumption

Modern wireless systems demand compact, power-efficient radio frequency (RF) front-end components that support wideband tunability and nonreciprocity. We present a class of miniature bandpass filter that achieves both continuously tunable frequency operation (4.0-17.7 GHz) and high nonreciprocity ( > 25 dB), all within a compact size of 1.07 cm³. The filter employs a microfabricated 18 µm thick Yttrium Iron Garnet (YIG) 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).