Tunable Filtered RF Power Amplifier for Receiver Wraparound Suppression
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Solution Overview
Problem
High frequency front-end circuits face signal-to-noise ratio deterioration due to wraparound of transmission signals into receiver side circuits, particularly when frequency bands for transmission and reception are close, leading to unwanted amplification of reception frequency components.
Innovation Solution
A multimode/multiband high frequency power amplifier configuration that includes a first wide band high frequency amplifier, a final wide band high frequency amplifier, and a tunable filter connected between them, which provides attenuation in specific frequency bands to prevent unwanted signal components from reaching the receiver, along with isolators to prevent impedance mismatching and ensure desired signal levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a wide band high frequency amplifier is used to amplify transmission signals across multiple frequency bands, then the gain in wide band is improved, but the reception frequency component of the transmission signal is undesirably amplified and wraps around the receiver side circuit
Solution Approach 1:
The amplifier is divided into multiple stages (first high frequency amplifier, second high frequency amplifier) with a tunable filter inserted between them. This segmentation allows the system to apply different frequency characteristics at different stages, enabling wide band amplification while selectively attenuating reception frequency components through the tunable filter.
Solution Approach 2:
A tunable filter is introduced as an intermediary component between the first and second high frequency amplifiers. This filter acts as a mediator that selectively attenuates reception frequency components of the transmission signal while allowing the desired transmission frequency components to pass through, thereby preventing wraparound to the receiver side circuit.
2Adaptability or versatility
If the number of communication bands is increased to support diversification of communication bands, then the adaptability is improved, but the reception frequency component of the transmission signal tends to wrap around the receiver side circuit
Solution Approach 1:
The tunable filter is configured to dynamically adjust its attenuation characteristics based on the active communication band. When different communication bands are used, the filter's attenuation frequency can be tuned to correspond to the reception frequency of that band, enabling effective suppression of wraparound across multiple communication bands while maintaining adaptability.
3Object-affected harmful factors
If a tunable filter is inserted between amplifiers to suppress reception frequency components, then the wraparound is reduced, but the device complexity increases
Solution Approach 1:
The tunable filter is designed to perform multiple functions: it attenuates reception frequency components to prevent wraparound, maintains wide band amplification characteristics, and adapts to different communication bands. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity despite the addition of the filter.
Data Source
AI summary
A high frequency power amplifier includes a first high frequency amplifier, a final high frequency amplifier, and a tunable filter. The tunable filter is connected between the first high frequency amplifier and the final high frequency amplifier. The first high frequency amplifier and the final high frequency amplifier are each a multimode/multiband power amplifier. The tunable filter is regulated such that its pass band includes the frequency band of a transmission signal and its attenuation band includes the frequency band of a reception signal in a communication band used in transmission and reception. The pass band and the attenuation band are switched by the tunable filter in accordance with the communication band used in transmission and reception.