A minimal diffraction cut of quartz for high performance SAW filters

Abbott, B. P.; Solie, L.P.

doi:10.1109/ultsym.2000.922547

Cited by 8 publications

(4 citation statements)

References 7 publications

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“…3 (a) Fig 3 ( considering in their analysis TCD, γ, and PFA. The experimental results reported in [4] show measured diffraction of -0.97, zero TCD, 0.135% for K 2 , and zero PFA, which is consistent with the predicted in this work. It is interesting to mention that ∠Γ u is -46.2° which denotes some degree of directivity in the (0°, 43.8°, 23.2°) orientation.…”

Section: B Optimal Orientations For Quartz (0° θ ψ)supporting

confidence: 91%

“…Note that the (0°, 43.8°, 23.2°) orientation performance is superior with respect to ST-X even when diffraction is not included in the analysis. Table III This optimal quartz orientation vicinity has been identified, discussed, and experimentally tested in [4], where the authors arrived at Euler angles (0°, 43°, 23.7°) by Fig. 3 (a) Fig 3 ( considering in their analysis TCD, γ, and PFA.…”

Section: B Optimal Orientations For Quartz (0° θ ψ)mentioning

confidence: 99%

“…In the past, orientations have been determined based on the simultaneous analysis of contour plots for v p , K 2 , TCD, and PFA [2] [3], and the definition of a three property scalar function for PFA, TCD, and γ, with fixed target values at 0°, 0 ppm/°C, and -1, respectively [4].…”

Section: Introductionmentioning

confidence: 99%

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Optimal orientation function for SAW devices

Cowperthwaite

Cunha

IEEE International Frequency Control Sympposium and PDA Exhibition Jointly With the 17th European Frequency and Time Forum, 200

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The traditional electromechanical coupling coefficient (K 2 ) and temperature coefficient of delay (TCD); more recently velocity (v p ), for compact or high frequency devices; and now power flow angle (PFA), diffraction (γ), amplitude (|Γ|) and phase (∠Γ) of a metal strip reflection coefficient are equally important in Surface Acoustic Wave (SAW) device design and operation.In this paper a novel function which simultaneously analyzes seven SAW propagation properties (v p , K 2 , TCD, PFA, γ, |Γ|, and ∠Γ) is discussed and implemented. This flexible function allows the search and selection of optimal propagation directions along arbitrary piezoelectric substrates by employing user defined criteria for each property analyzed which: (i) specify target values; (ii) set acceptable variations from the target values; (iii) assign desired weights; and (iv) normalize to the maximum property value variations for the orientations under study. Given a substrate and a set of basic propagation properties covering a region in the space or in a plane, the function outputs a scalar number for each orientation. The minima indicate optimal orientations with respect to the user defined search criteria and weights.Contour plots are given showing the function results with respect to orientations in space for different substrates, the historic quartz, and those of more recent interest, the LGX family of crystals. The results validate the usefulness of the optimal orientation function in locating optimal SAW propagation directions and regions in space. Using quartz, for example, attractive propagation properties are confirmed along Euler angles (0°, 43.8°, 23.2°): K 2 is 19% above ST-X, diffraction is minimal, γ and PFA are zero, and the reflection coefficient is almost four times higher than ST-X. Comparisons with previously reported experimental results on quartz and the LGX family of crystals are given.

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Section: B Optimal Orientations For Quartz (0° θ ψ)supporting

confidence: 91%

Section: B Optimal Orientations For Quartz (0° θ ψ)mentioning

confidence: 99%

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Optimal orientation function for SAW devices

Cowperthwaite

Cunha

IEEE International Frequency Control Sympposium and PDA Exhibition Jointly With the 17th European Frequency and Time Forum, 200

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“…1) There has been some studies of tapered or SFIT SAW filters on minimal diffraction cut substrates such as LGS or quartz. 2) Although such minimal diffraction cut substrates have been examined for maintaining zero power flow angle (PFA), the PFA cannot be equal to zero. For example, the PFA of a commercially available ð0 ; 138:5 ; 26:7 Þ LGS substrate is À0:7 on a catalogue that is calculated from material constants.…”

Section: Introductionmentioning

confidence: 99%

Power Flow Angles for Slanted Finger Surface Acoustic Wave Filters on Langasite Substrate

Goto

Yatsuda

Chiba

2007

jjap

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Power flow angles (PFAs) on a langasite (LGS) substrate with Euler angles of (0°, 138.5°, ψ), ψ=25.7 to 27.7° are investigated for slanted finger interdigital transducer (SFIT) surface acoustic wave (SAW) filters by an electrical and optical methods. In the electrical method, several tilted SFIT SAW filters with different tilt angles for (0°, 138.5°, ψ) LGS substrates were designed, and the frequency responses of the filters were measured. In the optical method, the PFAs were directly measured by optical probing for a parallel interdigital transducer (IDT) with wide propagation area on the substrate. As a result, a good correlation between electrical and optical measurements of the PFAs is obtained, but the calculated PFAs are slightly different from the measured PFAs. A good frequency response of a tilted 380 MHz SFIT SAW filter with an appropriate tilt angle corresponding to the PFA on the substrate is obtained even though the aperture is small.

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