Separate I/Q Power Amplification for Better Antenna Matching
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Solution Overview
Problem
Mobile wireless communications devices face interference issues due to conducted or near-field radiated energy from power amplifiers and other components, leading to degradation of total radiated power (TRP) and harmonic interference, particularly in GSM systems and with In-phase (I) and Quadrature (Q) modulation schemes.
Innovation Solution
The implementation of a mobile wireless communications device with separate In-phase and Quadrature power amplifier circuits, each with a controller for closed-loop biasing, and a power combiner that isolates and combines these signals to enhance antenna matching and reduce harmonic emission, using a 3 dB quadrature hybrid power combiner to achieve better linearity and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate In-phase and Quadrature power amplifier circuits are used, then linearity and antenna matching are improved, but device complexity increases
Solution Approach 1:
The power amplification function is segmented into separate In-phase and Quadrature power amplifier circuits, each handling one component independently. This segmentation allows each amplifier to operate more linearly with better control, improving overall linearity and antenna matching performance.
Solution Approach 2:
The separate In-phase and Quadrature power amplifier outputs are merged through a power combiner to produce the final RF output signal. This combining approach maintains the linearity benefits of separate amplification while delivering the required composite signal to the antenna.
2Power
If separate In-phase and Quadrature power amplifier circuits are used, then total radiated power is enhanced, but device complexity increases
Solution Approach 1:
The power amplification function is segmented into separate In-phase and Quadrature power amplifier circuits, each handling one component independently. This segmentation allows each amplifier to operate more linearly with better control, improving overall linearity and antenna matching performance.
Solution Approach 2:
The separate In-phase and Quadrature power amplifier outputs are merged through a power combiner to produce the final RF output signal. This combining approach maintains the linearity benefits of separate amplification while delivering the required composite signal to the antenna.
3Volume of moving object
If components are placed closer together to reduce device size, then device size is reduced, but conducted energy interference increases
Solution Approach 1:
A power combiner is introduced as an intermediary component between the separate power amplifier circuits and the antenna. This intermediary structure provides isolation and controlled combining of signals, reducing conducted energy interference between components while maintaining compact device dimensions.
Data Source
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AI summary
A mobile wireless communications device includes a housing an antenna, and radio frequency (RF) circuitry. A transceiver is connected to the antenna and a processor is operative with the RF circuitry. The transceiver includes an In-phase and Quadrature (I/Q) Modulation and Power Amplification circuit having an In-phase (I) circuit with a modulator mixer and power amplifier circuit. A Quadrature (Q) circuit includes a modulator mixer and power amplifier circuit. A power combiner receives the separately amplified In-phase and Quadrature signals and sums and outputs the signals as a combined I and Q signal. The I and Q circuits are isolated from the combined I and Q signal to enhance antenna matching and transmitted radiated power (TRP) and reduce harmonic emission from the power amplification circuits.