Carrier Aggregation Power Amplifier Control for IMD Suppression
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Solution Overview
Problem
In wireless communication systems using carrier aggregation, inter modulation distortion (IMD) occurs when signals from multiple component carriers are amplified by a single power amplifier, leading to interference across frequency bands, and existing solutions either increase power consumption or device size and cost.
Innovation Solution
A wireless communication apparatus that includes an amplifying unit, a measuring unit to detect IMD, a determining unit to assess if IMD levels exceed a regulation value, and a control unit to adjust signal power or amplifier voltage to maintain compliance with the regulation value, thereby suppressing IMD.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If signals of multiple component carriers are amplified by a single power amplifier, then device size and cost are reduced through shared transmission circuits, but inter modulation distortion is generated causing interference in frequency bands
Solution Approach 1:
A distortion compensation unit is introduced as an intermediary component between the power amplifier and the antenna. This unit generates a distortion compensation signal that counteracts the inter modulation distortion produced by the power amplifier, thereby suppressing the harmful interference while maintaining the benefit of using a single shared amplifier
Solution Approach 2:
The system employs a feedback mechanism where the distortion compensation signal is generated based on the actual distortion characteristics of the power amplifier. The compensation unit continuously adjusts the compensation signal to match the distortion produced, creating a closed-loop system that effectively suppresses inter modulation distortion
2Object-generated harmful factors
If power supply voltage to power amplifier is increased to raise saturation level and suppress inter modulation distortion, then distortion is reduced, but electrical power consumption increases
Solution Approach 1:
Instead of increasing power supply voltage, the system uses a distortion compensation signal as an intermediary to suppress inter modulation distortion. This approach achieves distortion reduction through signal processing rather than electrical parameter changes, thereby avoiding increased power consumption
Solution Approach 2:
The system changes the approach from electrical parameter modification (voltage increase) to signal parameter modification (distortion compensation signal). By altering the signal characteristics rather than the electrical operating conditions, the system suppresses distortion without the associated power penalty
3Object-generated harmful factors
If separate power amplifiers are provided for each component carrier to avoid inter modulation distortion, then distortion is eliminated, but device size and cost increase
Solution Approach 1:
The patent merges multiple separate power amplifiers into a single shared power amplifier for multiple component carriers. By combining the amplification function into one unit and adding distortion compensation, the system eliminates the need for multiple amplifiers while still controlling inter modulation distortion
Solution Approach 2:
The distortion compensation unit serves as an intermediary that enables a single power amplifier to handle multiple component carriers without generating harmful distortion. This intermediary component makes the merged configuration viable by actively suppressing the distortion that would otherwise require separate amplifiers
Data Source
AI summary
A wireless communication apparatus includes an amplifying unit that amplifies an input signal that includes signals with different frequencies of a first frequency and the second frequency; a measuring unit that measures a level of inter modulation distortion generated in a signal obtained by the input signal being amplified by the amplifying unit; a determining unit that determines whether the level of the inter modulation distortion measured by the measuring unit is equal to or greater than a regulation value that is previously stored; and a control unit that decreases, when a result of the determination obtained by the determining unit indicates that the level of the inter modulation distortion is equal to or greater than the regulation value, a level of a signal input to the amplifying unit.