Band Reject Duplexer Structure for High-Power Acousto-Migration Control
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Solution Overview
Problem
Conventional duplexers/multiplexers with acoustic-type resonators have limited maximum power handling capabilities and are prone to acousto-migration at high-power, high-frequency applications, leading to reduced filter lifetime in wireless communications devices.
Innovation Solution
Implementing a multi-port path selection structure with a band reject filter connected to the transmit path and a bandpass or band reject filter connected to the receive path, using acoustic-type resonators in a ladder-type configuration to reduce acousto-migration and enhance power handling capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional bandpass filters with acoustic-type resonators are used in duplexers/multiplexers, then the device can achieve frequency selectivity and signal separation, but the maximum power handling capability is limited and acousto-migration occurs at high-power, high-frequency applications
Solution Approach 1:
The patent changes the filter type from conventional bandpass filters to band reject filters, fundamentally altering the filtering mechanism. Band reject filters are less susceptible to acousto-migration and can handle higher power levels, directly resolving the contradiction between power handling capability and filter lifetime
Solution Approach 2:
The patent employs a composite filter structure combining band reject filter elements with acoustic-type resonators in a ladder-type configuration. This composite approach leverages the high power handling of band reject filters while maintaining the frequency selectivity benefits of acoustic resonators, achieving both improved power capability and reliability
2Power
If high-power transmit signals are transmitted through conventional bandpass filters, then communication power requirements are met, but ultrasonic vibration causes acousto-migration in metallic electrodes, reducing filter lifetime
Solution Approach 1:
The patent changes the filter configuration to band reject filters, which operate with different mechanical stress characteristics that reduce ultrasonic vibration in metallic electrodes. This parameter change eliminates acousto-migration while maintaining high-power transmit signal capability
Solution Approach 2:
The patent converts the potential harmful effect of high-power signals by using band reject filters that are inherently more resistant to power-induced degradation. The high-power signals that would cause acousto-migration in bandpass filters are handled safely by the band reject filter configuration, turning a harmful scenario into a beneficial operating condition
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively handles high-power transmit signals with reduced acousto-migration issues, providing longer filter lifetime and improved performance in high-power, high-frequency applications like WiMax and LTE networks.
Implementation Method 1
high-power and high-frequency communications can cause ultrasonic vibration in metallic electrodes of the acoustic-type resonators, which can lead to a phenomenon referred to as acousto-migration, in which metal grain boundaries in the resonators migrate
Data Source
AI summary
A wireless communications device includes an antenna, a multi-port path selection structure having an antenna port connected to the antenna, and plural ports connected to respective one or more receive and transmit paths of the wireless communications device. The multi-port path selection structure has a transmit band reject filter connected to the transmit path and a second filter connected to the receive path.