Power Amplifier Combiner Phase Shifting for Impedance Isolation
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Solution Overview
Problem
Existing power amplifier configurations face limitations in achieving high output power and linearity, particularly in communication standards like LTE-Advanced, due to impedance mismatch and phase imbalance issues.
Innovation Solution
A power amplifier module design that includes a divider circuit, amplifiers, a combining circuit with inductors and capacitors for phase shifting, and a resistance element with a capacitor in parallel, which ensures isolation and impedance matching by delaying and advancing signal phases to cancel out signal amplitudes between amplification paths, allowing for improved impedance characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single passive element is used for impedance matching between amplifier elements and load side, then the configuration is simple, but the imaginary part of impedance becomes substantially maximum and linearity improvement is limited
Solution Approach 1:
The single passive element impedance matching network is segmented into multiple passive elements (inductors and capacitors) arranged in specific configurations. This segmentation allows independent optimization of real and imaginary impedance components, enabling better linearity while maintaining manageable complexity through modular design.
Solution Approach 2:
The patent uses composite passive element structures combining multiple inductors and capacitors to create an impedance matching network that simultaneously optimizes both real and imaginary impedance components. This composite approach enables achieving substantial maximum imaginary part reduction while improving linearity, resolving the contradiction between simplicity and performance.
2Device complexity
If amplifier elements are connected without isolation resistance, then the configuration is simple, but signal leakage between paths occurs and isolation is poor
Solution Approach 1:
An isolation resistance element is introduced as an intermediary component connected between the output terminals of amplifier elements. This intermediary element provides a controlled impedance path that absorbs signal leakage while maintaining overall system performance, achieving good isolation without excessive complexity.
3Device complexity
If the impedance on the load side is not optimized, then the configuration is simple, but the performance of amplifier elements cannot be maximized
Solution Approach 1:
The patent systematically adjusts impedance parameters (resistance, inductance, capacitance values) of the matching network to optimize the load side impedance. By changing these parameters, the real part of impedance is minimized while maintaining a substantially maximum imaginary part, enabling amplifier elements to operate at maximum performance with improved output power.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables high output power and linearity by ensuring isolation between amplifiers and optimizing impedance, thereby enhancing the performance of power amplifiers in unbalanced modes and improving linearity beyond the limitations of previous configurations.
Implementation Method 1
a first capacitor connected in parallel to the resistance element. A phase of the third signal from the output terminal of the first amplifier to the output terminal of the second amplifier through the first capacitor is advanced by about 90 degrees
Implementation Method 2
a first inductor connected in series between the output terminal of the first amplifier and the combiner, a second inductor connected in series between the output terminal of the second amplifier and the combiner
Implementation Method 3
a second capacitor having an end connected to the combiner and another end grounded. A phase of the third signal from the output terminal of the first amplifier to the output terminal of the second amplifier through the first inductor and the second capacitor is delayed by about 45 degrees
Data Source
AI summary
A power amplifier module includes a combining circuit including a combiner. The combining circuit further includes a first inductor connected in series between an output terminal of a first amplifier and the combiner, a second inductor connected in series between an output terminal of a second amplifier and the combiner, and a second capacitor having an end connected to the combiner and another end grounded. A phase of a third signal from the output terminal of the first amplifier to the second amplifier through the combiner is delayed by about 45 degrees in the first inductor and the second capacitor, and is delayed by about 45 degrees in the second inductor and the second capacitor. A phase of the third signal from the output terminal of the first amplifier to the second amplifier through the first capacitor is advanced by about 90 degrees.