Quadrature Hybrid Coupler Tuning for Broadband Doherty RF Amplifiers
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Solution Overview
Problem
In 5G communication systems using ultra-high frequency bands, there is a challenge in maintaining signal balance and efficiency due to amplitude and phase differences between in-phase (I) and quadrature (Q) signals, particularly at frequencies away from the center frequency, which affects the performance of power amplifiers in RF circuits.
Innovation Solution
A frequency-tunable quadrature hybrid coupler is introduced in the power amplifier, equipped with switches that adjust the inductance of the couplers' transmission paths, ensuring the I and Q signals maintain a 90-degree phase difference and balanced amplitudes across various frequency bands, including mmWave bands like n257 and n258.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed-frequency coupler is used to generate I and Q signals, then the phase and amplitude balance is maintained at the center frequency, but the signal balance deteriorates at frequencies far from the center frequency
Solution Approach 1:
The coupler's electrical length is made dynamically adjustable through switched capacitor networks that can change the effective capacitance values based on the operating frequency band. This allows the coupler to adapt its phase response to maintain proper I-Q signal balance across different frequency bands, resolving the contradiction between fixed-frequency precision and broadband adaptability
Solution Approach 2:
The invention changes the electrical parameters (capacitance values) of the coupler components to optimize performance for different frequency bands. By switching between different capacitor configurations, the coupler maintains accurate phase and amplitude relationships across multiple bands, addressing both the precision and versatility requirements
2Adaptability or versatility
If the coupler electrical length is adjusted for different frequency bands, then the signal balance is maintained across bands, but the device complexity increases
Solution Approach 1:
The coupler is segmented into modular sections with switched capacitor networks at strategic points. This segmentation allows independent adjustment of different electrical length parameters without redesigning the entire coupler, reducing the complexity increase while maintaining broadband adaptability
Solution Approach 2:
The switched capacitor networks serve multiple functions: they adjust electrical length for phase balance, provide impedance matching for different bands, and can be controlled through a unified control mechanism. This multi-functionality reduces the overall complexity compared to having separate adjustment mechanisms for each parameter
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
This solution enables a broadband Doherty power amplifier that simultaneously covers adjacent 5G NR bands, minimizing signal imbalance and improving communication quality by adjusting electrical lengths in the coupler paths based on frequency bands, thereby enhancing the efficiency and performance of RF signals.
Implementation Method 1
a first switch capable of varying the inductance of the first inductor
Data Source
AI summary
An electronic device, according to various embodiments, may comprise: a power amplifier configured to amplify an input signal; an antenna module including at least one antenna and configured to transmit an RF signal amplified in a circuit of the power amplifier; and a communication processor including at least one processor, comprising processing circuitry, individually and/or collectively configured to control the power amplifier and the antenna module.