I and Q Power Amplifier Segmentation for Linearity
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Solution Overview
Problem
Mobile wireless communications devices face linearity issues with power amplifiers and antenna matching, leading to degradation of total radiated power and harmonic interference due to non-linearity, particularly in I and Q power amplifiers.
Innovation Solution
The implementation of separate power amplifier circuits for In-phase (I) and Quadrature (Q) signals, along with a power combiner and demodulator circuits, allows for improved linearity and phase compensation, enhancing antenna matching and reducing harmonic emission by isolating I and Q signal inputs and using a processor for selective phase shifting and predistortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate I and Q power amplifier circuits are used, then linearity is improved, but device complexity increases
Solution Approach 1:
The power amplification function is segmented into separate I and Q power amplifier circuits, each handling one component independently. This segmentation allows each amplifier to operate more linearly with dedicated bias control, resolving the linearity improvement while accepting increased circuit complexity as a necessary trade-off for performance.
Solution Approach 2:
Independent bias control parameters are applied to each power amplifier circuit to optimize their operating points. By changing the bias parameters separately for I and Q amplifiers, the system achieves better linearity and efficiency, addressing the technical contradiction through parameter optimization.
2Object-generated harmful factors
If separate I and Q power amplifier circuits are used, then harmonic emission is reduced, but device complexity increases
Solution Approach 1:
By segmenting the power amplification into separate I and Q circuits with independent control, each amplifier operates more efficiently with reduced non-linearity. This reduces harmonic emission as a harmful effect while accepting the complexity increase as necessary for meeting emission requirements.
Solution Approach 2:
The separate amplifier architecture converts the potential harm of non-linear operation into benefit by allowing independent optimization of each amplifier's operating point, reducing harmonic emission through better control rather than treating it as an aftereffect.
3Reliability
If I and Q signal inputs are isolated, then antenna matching is enhanced, but device complexity increases
Solution Approach 1:
The signal paths for I and Q components are segmented and isolated through separate amplifier circuits and independent bias control. This isolation prevents interaction between I and Q signals that would degrade antenna matching, while the resulting complexity is managed through modular circuit design.
4Use of energy by moving object
If selective phase shifting and predistortion are applied, then efficiency is improved, but device complexity increases
Solution Approach 1:
Predistortion is applied as a preliminary action to the I and Q signals before they reach the power amplifiers. By pre-adjusting the signals to compensate for expected non-linearities, the system improves efficiency and linearity while the complexity is contained in the signal processing stage rather than the power amplification stage.
Solution Approach 2:
Selective phase shifting and predistortion adjust the signal parameters (phase and amplitude) before amplification. These parameter changes optimize the operation of separate power amplifiers, improving overall efficiency while managing complexity through digital signal processing rather than analog circuit complexity.
Data Source
AI summary
A communications device may include an In-phase (I) circuit having an In-phase modulator and mixer circuit, and an I power amplifier circuit coupled thereto, the I circuit configured to modulate and amplify a digital baseband I signal to generate an amplified I signal, and a Quadrature (Q) circuit having a Q modulator and mixer circuit, and a Q power amplifier circuit coupled thereto, the Q circuit configured to modulate and amplify a digital baseband Q signal to generate an amplified Q signal separate from the amplified I signal. A processor selectively switches the digital baseband I signal and the digital baseband Q signal between the I and Q signal inputs to provide selective phase shifting for the digital baseband I and Q signals.