DCS Tx filters using AlN resonators with iridium electrodes

Area of Science:

• Electrical Engineering
• Materials Science
• Telecommunications

Background:

• Digital Cellular System (DCS) requires efficient filters for its Transmit (Tx) band.
• Existing Bulk Acoustic Wave (BAW) filter technologies face challenges in meeting specific bandwidth requirements.

Purpose of the Study:

• To design, fabricate, and characterize novel BAW filters for the DCS Tx-band at 1.75 GHz.
• To enhance the electromechanical coupling factor of BAW devices for improved performance.
• To validate simulation models against experimental results.

Main Methods:

• Utilized Aluminum Nitride (AlN)-based solidly mounted resonators (SMR) with iridium electrodes.
• Employed a circuit model simulation tool for filter design and optimization.
• Fabricated and experimentally tested various Tx filter topologies with balanced inputs/outputs.

Main Results:

• Achieved filter performance meeting DCS bandwidth requirements using Ir/AlN/Ir stacks.
• Demonstrated the suitability of the designed filters through comparison of experimental and simulated responses.
• Successfully increased the effective electromechanical coupling factor of BAW devices.

Conclusions:

• The developed Ir/AlN/Ir BAW filters are suitable for DCS Tx-band applications.
• The fabrication technology and design approach effectively address the bandwidth needs of DCS filters.
• Simulation tools accurately predict filter frequency response, aiding in design optimization.