Programmable Duplexer with Active Frequency Tuning
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Solution Overview
Problem
Current surface acoustic wave (SAW) duplexers struggle to meet the stringent frequency separation requirements of 3GPP bands 2, 3, and 8 due to narrow transition bands, which are further exacerbated by manufacturing and temperature variations.
Innovation Solution
A programmable duplexer with adjustable receiver and transmitter filters, controlled by a controller to optimize the transition band between the receiver and transmitter paths, allowing for selection of desired pass bands without the need for multiple filters, thereby reducing sensitivity to manufacturing tolerances and temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If standard SAW filters are used in duplexers, then the device structure is simple and manufacturing is easy, but the transition band is too narrow to meet 3GPP bands 2, 3, and 8 requirements
Solution Approach 1:
The patent implements dynamically adjustable filters using varactor diodes that can be tuned in real-time via control voltages. This allows the transition band to be dynamically widened to meet 3GPP band requirements while maintaining a relatively simple physical filter structure. The dynamic tuning capability enables the same hardware to adapt to different frequency separation requirements.
Solution Approach 2:
The patent changes the electrical parameters of the filter components by applying different control voltages to varactor diodes, which alters their capacitance values. This parameter adjustment modifies the filter's frequency response and transition band characteristics without changing the physical structure, thereby achieving wider transition bands for challenging 3GPP bands.
2Manufacturing precision
If SAW filters with high Q factors are used to achieve narrow transition bands, then the filter performance improves, but the system becomes highly sensitive to manufacturing tolerances and temperature variations
Solution Approach 1:
The patent incorporates control circuits that can adjust the varactor diode bias voltages based on detected frequency drift or performance degradation. This feedback mechanism compensates for manufacturing tolerances and temperature-induced frequency shifts, maintaining reliable filter performance across varying conditions while achieving the required transition band steepness.
Solution Approach 2:
By using dynamically tunable varactor-based filters instead of fixed SAW filters, the system can adapt to temperature variations and manufacturing tolerances in real-time. The dynamic adjustment capability allows the filter to maintain optimal performance characteristics despite environmental changes, reducing sensitivity to these factors.
3Adaptability or versatility
If multiple fixed duplexers are used to cover different channel pairs, then each duplexer can be optimized for specific bands, but the device complexity and number of components increases
Solution Approach 1:
The patent designs a universal programmable duplexer architecture where a single filter assembly with varactor-tuned elements can cover multiple channel pairs and frequency bands. By making the filters dynamically adjustable, one physical duplexer structure performs the function of multiple fixed duplexers, reducing component count while maintaining adaptability to different 3GPP band requirements.
Data Source
AI summary
Embodiments disclosed herein relate to programmable duplexers. The frequency pass band of the programmable duplexer is changed according to a selection of a channel-pair selection to control or maximize the transition band between the receiver path and the transmitter path. The programmable duplexer permits selections of desired pass bands without the need for multiple duplexer filters. As an additional advantage, the transmission band requirements become less sensitive to manufacturing tolerances and temperature variations.