Hybrid Duplexing Circuit Calibration for Antenna Impedance Isolation
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Solution Overview
Problem
Existing duplexing solutions for wireless communications, such as hybrid junctions, face challenges in achieving optimal isolation between transmit and receive signals due to variations in antenna impedance and manufacturing imperfections, leading to suboptimal performance and increased complexity.
Innovation Solution
A system that uses a hybrid circuit with a variable impedance and a controller to determine optimal impedance settings through a system of equations, associating measured signals with calibration measurements to achieve improved isolation, and an adaptive active signal cancellation subsystem to iteratively refine the impedance settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If diplexing filters are used to separate transmit and receive signals, then isolation between downlink and uplink transmissions is improved, but device complexity and size increase due to requiring one filter per frequency band
Solution Approach 1:
The patent combines multiple diplexing filter functions into a single reconfigurable filter that can be tuned to different frequency bands. This is achieved by using a single filter structure with adjustable resonant frequencies, eliminating the need for multiple discrete filters and RF switches, thereby reducing device complexity while maintaining signal isolation.
Solution Approach 2:
The patent employs a reconfigurable filter with dynamically adjustable resonant frequencies. The filter can be electronically tuned to different frequency bands on-demand, allowing a single filter to replace multiple fixed-frequency filters. This dynamic reconfiguration capability reduces the number of components needed while maintaining the isolation performance across multiple bands.
2Adaptability or versatility
If multiple discrete duplexers are used to support multiple frequency bands, then frequency band coverage is improved, but overall size and cost of the transceiver increase
Solution Approach 1:
The patent designs a universal reconfigurable filter that can operate across multiple frequency bands by adjusting its resonant frequency. This single multi-functional filter replaces the need for multiple band-specific filters, reducing the overall size of the transceiver while maintaining the capability to support multiple frequency bands.
Solution Approach 2:
The reconfigurable filter uses dynamic frequency tuning to adapt to different frequency bands. By electronically adjusting the resonant frequency of the filter, a single compact filter structure can cover multiple frequency bands that would otherwise require multiple larger fixed-frequency filters, thereby reducing the total area occupied.
3Adaptability or versatility
If RF switching is used to select between frequency bands, then frequency band selection is improved, but power losses increase due to the introduction of the RF switch
Solution Approach 1:
The patent replaces static RF switching with dynamic frequency tuning of a reconfigurable filter. Instead of using an RF switch to select between different filters, the system dynamically adjusts the resonant frequency of a single filter to match the desired frequency band. This eliminates the RF switch and its associated power losses while maintaining frequency band selection capability.
4Reliability
If acoustic resonator filters are used to provide low insertion loss and sharp roll-off, then filter performance is improved, but integration with CMOS circuit becomes impossible requiring off-chip implementation
Solution Approach 1:
The patent replaces mechanical acoustic resonators with an electronic implementation using a reconfigurable filter that can be integrated with CMOS circuits. The electronic filter uses variable capacitors or inductors to achieve frequency tuning, substituting the mechanical resonance mechanism with an electrical equivalent that is compatible with standard semiconductor manufacturing processes, enabling on-chip integration.
Data Source
AI summary
A duplexing apparatus comprises a reference of impedance settings and corresponding calibration measurements. A controller is arranged to set a variable impedance to a first impedance setting and transmit a first transmit signal at a first transmit frequency and measure a resulting first signal at an output node of a hybrid circuit. The controller then selects a second impedance setting, transmits a second transmit signal at a second transmit frequency and measures a resulting second signal at the output node. The controller then determines a balancing result using a system of equations associating the first and second measured signals, and first and second calibration measurements from the reference in respect of the first and second impedance settings, respectively. A third impedance setting is retrieved from the reference by reference to the balancing result to provide isolation of an input node from the output node of the hybrid circuit.