Fig. 4: Frequency splitter on HIP substrate.
From: Mode-determined unidirectional phonon transducers for minimal frequency splitter
a, c Function of the proposed frequency splitter and its schematic with electrical connection notation. The unidirectionality of SAW emission will split the frequency components in the mixed AC signal into two channels (colours represent the port name, DUT: device under test). b Simulated responses of the frequency splitter. Within the double-resonance frequency spectrum of the DMNUDT, acoustic modes constrain the emitting direction, furtherly channel selection can be accessed by frequency converge. Port impedances are 50 Ω. d Optical image of the fabricated frequency splitter with port notation. X direction of the transformed coordinate system is marked as “+” direction. Noted that port3 locates at “+” side with port2 at “-” side. The red dotted line refers to position for the cross profile in e. e Cross profile images by FIB-SEM. f, g Measured responses of the fabricated frequency splitter. Ports are matched to 97.5+i*130 Ω for measurement. f Port1 transducers is set for SAW propagate on −20X° direction. g for 20X° direction. Scale bars in d, e are 20 µm and 250 nm, respectively.
