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This paper demonstrates the first nonreciprocal network based on switched low-loss acoustic delay lines. The four-port circulator is built upon a recently reported frequency-independent, programmable, nonreciprocal framework based on switched delay lines. The design space for such a system, including the origins of the insertion loss (IL) and harmonic responses, is theoretically investigated, illustrating that the key to better performance and low-cost modulation signal synthesis lies in a large delay. To implement a large delay, we resort to in-house fabricated low-loss, wideband lithium niobate (LiNbO 3 )SH0 mode acoustic delay lines employing single-phase unidirectional transducers. The four-port circulator, consisting of two switch modules and one delay line module, has been modularly designed, assembled, and tested. The design process employs time-domain full circuit simulation, and the results match well with measurements. An 18.8-dB nonreciprocal contrast between IL (6.6 dB) and isolation (25.4 dB) has been achieved over a fractional bandwidth of 8.8% at a center frequency 155 MHz, using a record low switching frequency of 877.19 kHz. The circulator also shows 25.9-dB suppression for the intramodulated tone and 30 dBm for IIP3. Upon further development, such a system can potentially lead to future wideband, low-loss chip-scale nonreciprocal radio frequency systems with unprecedented programmability.

In permanent magnet applications, response often scales with volume or dimension in power-conversion and magnetostrictive applications, even in film form. In microelectromechanical devices it is necessary to explore versatile methods of dense film deposition with film thicknesses approaching one micron. In this study, we present a wet chemical route to hard magnetic cobalt ferrite (CoFe2O4) films to produce films with large coercivity, controllable thickness, saturation approaching that of the bulk, and smoother morphology than state-of-the art sputtered or pulsed-laser-deposited films. The development of etching and releasing processes demonstrates how these films are suitable for precise engineering in a variety of form factors and applications. © 2019 Author(s).

This paper demonstrates the first nonreciprocal network based on switched low-loss acoustic delay lines. The four-port circulator is built upon a recently reported frequency-independent, programmable, nonreciprocal framework based on switched delay lines. The design space for such a system, including the origins of the insertion loss (IL) and harmonic responses, is theoretically investigated, illustrating that the key to better performance and low-cost modulation signal synthesis lies in a large delay. To implement a large delay, we resort to in-house fabricated low-loss, wideband lithium niobate (LiNbO 3 )SH0 mode acoustic delay lines employing single-phase unidirectional transducers. The four-port circulator, consisting of two switch modules and one delay line module, has been modularly designed, assembled, and tested. The design process employs time-domain full circuit simulation, and the results match well with measurements. An 18.8-dB nonreciprocal contrast between IL (6.6 dB) and isolation (25.4 dB) has been achieved over a fractional bandwidth of 8.8% at a center frequency 155 MHz, using a record low switching frequency of 877.19 kHz. The circulator also shows 25.9-dB suppression for the intramodulated tone and 30 dBm for IIP3. Upon further development, such a system can potentially lead to future wideband, low-loss chip-scale nonreciprocal radio frequency systems with unprecedented programmability.

This paper reports on the demonstration of a new class of super-high frequency (SHF) microelectromechanical system (MEMS) resonators operating in the 5 GHz range. SHF resonances have been achieved using the first order antisymmetric (A1) mode, which features a phase velocity exceeding 10000 m/s in ion-sliced and suspended Z-cut Lithium Nio-bate (LiNbO3) thin films. The fabricated device has demonstrated a high electromechanical coupling (kt2) of 29% and a high quality factor (Q) of 527 simultaneously. Consequently, this work marks the first time that MEMS resonators at SHF were demonstrated with an extremely high figure of merit (FoM= kt2Q) of 153. The SHF operation and high FoM of these A1 mode devices have showcased their potential as the key building blocks for future SHF front-end filters and multiplexers. © 2017 IEEE.

This paper reports a 2.48 GHz tri-coil and rectifier design implemented in a system that demonstrates simultaneous wireless power transfer and communication to a 0.1 mm by 0.1 mm coil. The tri-coil link and rectifier successfully rectified and demodulated a 20 dBm amplitude-shift keyed (ASK) RF signal modulated at a rate of 1 Mb/s. Additionally, a 5.7 GHz tri-coil link was fabricated to validate the frequency scalability of this technology platform for other unlicensed bands and was measured in a customized experimental testbed to account for the effects of lateral misalignment between coils. The 5.7 GHz tri-coil design had a measured peak RF power transfer efficiency of -29 dB with a vertical separation of 1 mm, which is ten times the load coil diameter. © 2017 IEEE.