High-Isolation SAW Duplexer With On-Chip SAW Compensation Circuit Optimized for Isolated Multiple Frequency Bands

Area of Science:

• Electrical Engineering
• Materials Science
• Telecommunications

Background:

• Surface-acoustic wave (SAW) duplexers are crucial for mobile communication systems.
• Improving isolation between transmitter (Tx) and receiver (Rx) bands is essential for higher sensitivity.
• Existing SAW duplexers face challenges with signal leakage across multiple frequency bands.

Purpose of the Study:

• To develop and verify a new SAW duplexer with enhanced isolation using an on-chip compensation circuit.
• To analyze the cancellation of leakage signals in multiple frequency bands.
• To validate the proposed method for Long-Term Evolution (LTE) Band-I applications.

Main Methods:

• Simulation analysis of amplitude and phase changes in SAW duplexers.
• Circuit simulation using coupling-of-mode (COM) theory for a three-interdigital transducer (IDT) double-mode SAW (DMS) resonator.
• Experimental verification of the proposed SAW compensation circuit in an LTE Band-I SAW duplexer.

Main Results:

• Achieved approximately 10-dB improvement in Tx and Rx band isolation.
• Demonstrated that the isolation enhancement did not negatively impact other critical properties like insertion loss and attenuation.
• Simulation results closely matched experimental findings.

Conclusions:

• The developed SAW on-chip compensation circuit effectively cancels leakage signals.
• The new SAW duplexer design offers a viable solution for enhancing isolation in mobile communication devices.
• This advancement is significant for future mobile systems requiring superior Rx sensitivity across multiple bands.