Quadrature Feedback Transmitter Linearisation With Faster Phase Training
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Solution Overview
Problem
Current wireless communication systems face challenges in achieving high linearity and efficiency in RF power amplifiers due to non-linear quantum processes, leading to significant delays in transmitter training and potential interference from phase adjustments, particularly in spectrally efficient linear modulation schemes like π/4 DQPSK, which require precise phase and amplitude control.
Innovation Solution
A wireless communication unit with a novel quadrature generation and phase shifting architecture that employs independent mixers for 'I' and 'Q' quadrature signals, utilizing a single divide-by-2 quadrature generator and a real-time Cartesian feedback loop to minimize IQ imbalance and reduce component count, allowing for faster phase training and reduced noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional linearisation techniques with multiple control circuits are used, then linearity performance is improved, but device complexity and training time increase
Solution Approach 1:
The patent combines multiple control functions (phase adjustment, amplitude adjustment, and quadrature generation) into a single integrated controller that manages all linearisation parameters. This merging of control circuits reduces device complexity while maintaining linearity performance through unified coordination of all adjustment mechanisms.
Solution Approach 2:
The controller is designed as a multi-functional unit that simultaneously performs phase shifting, amplitude control, and quadrature signal generation. This universal controller eliminates the need for separate dedicated circuits for each function, reducing overall system complexity while preserving precise linearity control.
2Measurement precision
If multiple quadrature generators and frequency doublers are used, then phase control precision is improved, but component count and cost increase
Solution Approach 1:
The patent uses a single quadrature generator that produces both I and Q signals, eliminating the need for multiple separate quadrature generators. Frequency doubling functions are integrated into the existing signal path rather than using dedicated frequency doubler components, reducing the total component count while maintaining phase control precision through careful signal routing and phase adjustment.
3Manufacturing precision
If comprehensive phase and amplitude adjustments are made, then transmitter linearity is improved, but training delay increases
Solution Approach 1:
The system performs preliminary coarse adjustments of phase and amplitude parameters before fine-tuning during the actual training sequence. By pre-configuring adjustment ranges and initial values based on operating conditions, the comprehensive adjustments required for optimal linearity can be executed more quickly, reducing training delay while maintaining precision.
Solution Approach 2:
The linearisation adjustments are performed periodically at key operational transitions rather than continuously. The controller updates phase and amplitude parameters at discrete training intervals, allowing the system to achieve comprehensive linearity optimization without the time penalty of continuous adjustment, thus reducing overall training delay.
Data Source
AI summary
A wireless communication unit includes a frequency generation circuit, and a linearised transmitter operably coupled to the frequency generation circuit and having a forward path for routing a signal to be transmitted; and a feedback path, operably coupled to a power amplifier and the forward path for feeding back a portion of the signal to be transmitted. The feedback path and forward path form two loops in quadrature. The frequency generation circuit includes independent phase shift elements arranged to independently phase shift the two loops in quadrature (‘I’ and ‘Q’).