Novel Temperature-Compensated, Silicon SAW Design for Filter Integration

• Published in: IEEE microwave and wireless components letters Vol. 31; no. 6; pp. 674 - 677
• Main Authors: Ruby, R., Gilbert, S., Lee, S. K., Nilchi, J., Kim, S. W.
• Format: Journal Article
• Language: English
• Published: IEEE 01.06.2021
• Subjects: Acoustics; Apodization; front-end radios; hybrid substrate; integrated filters; Microwave filters; Power filters; Resonator filters; Resonators; Silicon; SiSAW; Substrates; surface acoustic device; temperature compensated (TC)-surface acoustic wave (TC-SAW)
• ISSN: 1531-1309; 1558-1764
• DOI: 10.1109/LMWC.2021.3068624

Today's phones have as many as 60 front-end radios covering multiple frequency bands. For each frequency band, acoustic filters offer high-<inline-formula> <tex-math notation="LaTeX">{Q} </tex-math></inline-formula>, good power handling, and linearity in a very small package. These properties are crucial when addressing the "explosion" in the number of radios and the filters needed by today's Smart Phones. Moving forward, filter integration will become essential for cost and size. A novel lithium tantalate (LT) bonded to silicon hybrid substrate silicon SAW (SiSAW) was developed that provides temperature compensation, good power handling properties, while mostly eliminating spurious modes created between the LT/Si interface. One of several advantages of this technique is that one can integrate as many filters as needed onto one die. This provides for cost savings as well as area savings while reproducing the inherent performance of high-quality temperature compensated (TC)-surface acoustic waves (TC-SAWs).