TPS259571DSGR_LQW18CAR27J00D Introduction

From a regional perspective, Japan closed the largest number of fabs. It is reported that Renesas expects to close two more 150mm fabs in 2020 or 2021. Take Renesas as an example. The company's two recently closed fabs are both 150mm, including a fab in Kochi Prefecture, Japan, which produces analog, logic devices and some obsolete micro components. In addition, Renesas has adjusted its factory in Otsu, Shiga Prefecture, Japan, to manufacture optoelectronic devices.

The TI BAW oscillator is an electronic oscillator circuit that utilizes the piezoelectric effect to generate a stable electronic signal through the mechanical resonance of a vibrating miniature acoustic resonator (BAW). This precise high-frequency signal provides a clock and timing reference for electronic systems.

TPS259571DSGR_LQW18CAR27J00D

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The most basic structure of the BAW filter is that two metal electrodes sandwich a piezoelectric film (the thickness of the Quartz substrate is 2um at 2GHz), and the acoustic wave oscillates in the piezoelectric film to form a standing wave.

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"Quartz crystals require additional components to extend their accuracy -- over time -- as their performance changes beyond controllable temperature changes," he added. In addition, Solis said, "using a BAW resonator is more efficient than using a quartz crystal. precise.

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TPS259571DSGR_LQW18CAR27J00D

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When asked why nobody in the industry has built something like a BAW resonator, Upton said, "It's very difficult to develop. But it's not easy to convert electrical energy into mechanical acoustics while keeping the signal stable and robust within a clean clock." TI has been involved in MEMS research for many years.

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. In order to keep the acoustic wave in the piezoelectric film to oscillate, there must be sufficient isolation between the oscillating structure and the external environment to obtain a small loss and a large Q value. On the other side of the oscillating structure, the acoustic impedance of the piezoelectric material is not much different from that of other substrates (such as Si), so the piezoelectric layer cannot be deposited directly on the Si substrate. The propagation speed of sound waves in solids is ~5000m/s, which means that the acoustic impedance of solids is about 105 times that of air, so 99.995% of the sound wave energy will be reflected back at the boundary between the solid and the air, which is the same as the original wave (incident wave). together to form a standing wave.

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TPS259571DSGR_LQW18CAR27J00D

Physically, waves are mainly divided into two types, one is electromagnetic wave, which does not require any medium, but propagates through the periodic oscillation of the electric and magnetic fields generated by the initially charged particles, so in a vacuum can also spread. Radio waves, microwaves, visible light, X-rays, and gamma rays are all electromagnetic waves.

The Membrane type is similar to the basic model of the BAW resonator, with air on both sides. Since the acoustic impedance of the air is much lower than that of the piezoelectric layer, most of the acoustic waves will be reflected back.

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