Solid State Tunable Filter Linearisation via Digital Pre-Distortion
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Solution Overview
Problem
Conventional RF filter apparatus, including switched filter banks, non-solid state tunable filters, and solid state tunable filters, face challenges such as redundancy, high cost, mechanical fragility, slow reconfiguration, and insufficient power handling capability and linearity for high-powered radio applications.
Innovation Solution
A linearisation system that includes a solid state tunable filter and Digital Pre-Distortion (DPD) means, where the DPD is applied to the solid state tunable filter to improve its linearity, power handling capability, and reconfiguration speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional solid state tunable filters are used, then the apparatus can be compact and lightweight, but the power handling capability and linearity are insufficient for high-powered radio applications
Solution Approach 1:
The patent replaces mechanical tunable filter systems with solid state electronic tuning using varactor diodes. This substitution eliminates mechanical components while achieving frequency tunability through electronic means, thereby improving reliability and enabling better power handling capability without sacrificing linearity.
Solution Approach 2:
The patent employs varactor diodes to change the resonant frequency of the filter by varying the reverse bias voltage applied to the diodes. This parameter change approach allows electronic tuning of the filter frequency while maintaining solid state construction, thus achieving both compact size and improved power handling capability with adequate linearity.
2Reliability
If switched RF filter banks are used, then sufficient linearity and power handling capability can be achieved, but the apparatus becomes large, heavy and costly
Solution Approach 1:
The patent designs a single solid state tunable filter that can operate across multiple frequency bands by electronically adjusting its resonant frequency. This universal filter replaces the need for multiple fixed-frequency filters in a filter bank, significantly reducing the apparatus weight, size, and cost while maintaining adequate linearity through solid state construction.
Solution Approach 2:
The patent combines multiple filter functions into a single solid state tunable filter unit. By merging the functionality of what would traditionally require multiple separate filters into one integrated solid state device, the apparatus weight and complexity are reduced while maintaining the necessary linearity and power handling capabilities.
3Adaptability or versatility
If non-solid state tunable filters are used, then mechanical tuning capability is achieved, but the apparatus suffers from mechanical fragility and slow reconfiguration
Solution Approach 1:
The patent replaces mechanical tuning mechanisms with solid state electronic tuning using varactor diodes. This substitution eliminates moving parts and mechanical fragility while achieving fast electronic reconfiguration. The filter frequency is tuned by changing the reverse bias voltage on the varactor diodes, providing both mechanical robustness and adaptability.
Solution Approach 2:
The patent implements dynamic electronic tuning capability through varactor diodes that can be rapidly reconfigured by changing their bias voltage. This dynamic control approach replaces slow mechanical adjustment mechanisms, enabling fast reconfiguration while maintaining mechanical robustness through the solid state implementation with no moving parts.
4Reliability
If fixed (non-tunable) filters are used, then very high linearity is achieved, but the apparatus lacks reconfigurability for different frequency bands
Solution Approach 1:
The patent uses varactor diodes to change the resonant frequency parameter of the filter by varying the reverse bias voltage. This allows the filter to be reconfigured for different frequency bands while maintaining solid state construction and good linearity. The parameter change approach provides adaptability without sacrificing the linearity characteristics essential for high-powered radio applications.
Data Source
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AI summary
A linearisation system is provided for use with radio frequency transmitter or transceiver apparatus. The system includes radio frequency input means for allowing one or more radio frequency signals to be input into the system in use and radio frequency output means for allowing one or more radio frequency signals to be output from the system in use. Digital Pre-Distortion (DPD) means are provided for linearising the one or more radio frequency signals passing through the linearisation system between the radio frequency input means and the radio frequency output means in use. At least one solid state tunable filter means is provided to filter the one or more radio frequency signals and optionally allow adjustment of the resonating radio frequency of the solid state tunable filter means if required in use. The solid state tunable filter means is provided in and/or associated with a DPD means, thereby providing improved linearity to the solid state tunable filter means in use.