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We present the first group of GHz broadband SH0 mode acoustic delay lines (ADLs). The implemented ADLs adopt unidirectional transducer designs in a suspended X-cut lithium niobate thin film. The design space of the SH0 mode ADLs at GHz is first theoretically investigated, showing that the large coupling and sufficient spectral clearance to adjacent modes collectively enable the broadband performance of SH0 delay lines. The fabricated devices show 3-dB fractional bandwidth ranging from 4% to 34.3% insertion loss between 3.4 and 11.3 dB. Multiple delay lines have been demonstrated with center frequencies from 0.7 to 1.2 GHz, showing great frequency scalability. The propagation characteristics of SH0 in lithium niobate thin film are experimentally extracted. The demonstrated ADLs can potentially facilitate broadband signal processing applications. [ABSTRACT FROM AUTHOR]

We present the first group of gigahertz S0 mode low loss and wideband acoustic delay lines (ADLs). The ADLs use a single-phase unidirectional transducers (SPUDT) design to launch and propagate the S0 mode in an X-cut lithium niobate thin film with large electromechanical coupling and low damping. In this work, the theoretical performance bounds of S0 mode ADLs are first investigated, significantly surpassing those in state-of-the-art. The design tradeoffs of S0 mode ADLs, when scaled to the gigahertz frequency range, are also discussed. The fabricated miniature ADLs show a fractional bandwidth (FBW) of 4% and a minimum insertion loss (IL) of 3.2 dB, outperforming the incumbent surface acoustic wave (SAW) counterparts, and covering a wide range of delays from 20 to 900 ns for digitally addressable delay synthesis. Multiple ADLs with center frequencies from 0.9 to 2 GHz have been demonstrated, underscoring their great frequency scalability. The propagation properties of S0 waves in lithium niobate at the gigahertz range are experimentally extracted. The demonstrated ADLs can potentially enable wide-range and high-resolution delay synthesis that is highly sought after for the self-interference cancellation in full-duplex radios. [ABSTRACT FROM AUTHOR]

This paper demonstrates low-loss acoustic delay lines (ADLs) based on shear-horizontal waves in thin-film LiNbO3 for the first time. Due to its high electromechanical coupling, the shear-horizontal mode is suited for producing devices with large bandwidths. Here, we show that shear-horizontal waves in LiNbO3 thin films are also excellent for implementing low-loss ADLs based on unidirectional transducers. The high acoustic reflections and large transducer unidirectionality induced by the mechanical loading of the electrodes on a LiNbO3 thin film provide a great tradeoff between delay line insertion loss and bandwidth. The directionality for two different types of unidirectional transducers has been characterized. Delay lines with variations in the key design parameters have been designed, fabricated, and measured. One of our fabricated devices has shown a group delay of 75 ns with an IL below 2 dB over a 3-dB bandwidth of 16 MHz centered at 160 MHz (fractional bandwidth = 10%). The measured insertion loss for other devices with longer delays and different numbers of transducer cells are analyzed, and the loss contributing factors and their possible mitigation are discussed. [ABSTRACT FROM AUTHOR]

This paper presents the first demonstration of chirp compressors based on laterally vibrating modes in suspended lithium niobate thin films. Both shear-horizontal and length-extensional modes have been explored and demonstrated with the electromechanical coupling coefficients of 30% and 39%, respectively, in a double-dispersive delay line structure. The high electromechanical coupling, along with the low propagation loss in the suspended thin film, produces a low insertion loss of 10 dB over a large fractional bandwidth of 50%. The best fabricated device demonstrates a delay-bandwidth product of 100, and provides a voltage gain of 5 to the corresponding chirp signals. Moreover, significant signal-to-noise ratio enhancements (>100), collectively enabled by the processing gain and filtering characteristics of the chirp compressors, have been demonstrated. The measured devices, in this paper, greatly outperform state-of-the-art chirp compressors based on surface acoustic waves in insertion loss for a comparable TB. As a result, signal-to-noise ratio enhancement and voltage gain have been simultaneously demonstrated for the first time in a passive device and the analog domain. The high performance can be harnessed to greatly enhance the sensitivity of near zero power wake-up radio receivers and enable low-power wireless connectivity for Internet of Things applications. [2017–0126] [ABSTRACT FROM PUBLISHER]