Multi-Branch RF Power Amplifier for Wideband Efficiency
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Solution Overview
Problem
Conventional power amplifiers (PAs) in base stations face challenges in achieving ultra-wideband and high efficiency due to conflicts between bandwidth and back-off, leading to low efficiency and high power consumption, especially in high-power scenarios, and isolators in ultra-wideband designs suffer from large insertion loss and poor linear indicators.
Innovation Solution
A radio frequency power amplifier with multiple amplification branches, circulators, and inter-frequency power division circuits is designed to convert wideband issues into narrowband ones, using narrowband PAs and circulators to improve efficiency, and a wideband branch provides power sharing, eliminating the need for wideband isolators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional power amplifier is designed for ultra-wideband operation, then the bandwidth is increased, but the efficiency decreases and power consumption increases due to large back-off area
Solution Approach 1:
The ultra-wideband signal is divided into multiple narrowband signals through frequency division. Each narrowband signal is processed by a dedicated narrowband power amplifier operating at its optimal efficiency point, avoiding the large back-off area problem of wideband PAs. The segmented narrowband outputs are then combined to reconstruct the wideband signal.
2Power
If the output power of the PA is increased to achieve high-power operation, then the power output is improved, but the size of internal power tubes increases and working bandwidth decreases due to parasitic parameters and impedance conversion
Solution Approach 1:
The high-power wideband amplification task is segmented into multiple narrowband amplification tasks. Each narrowband PA operates at moderate power levels within its optimal bandwidth, avoiding the bandwidth degradation caused by large power tube size and parasitic effects. The individual narrowband outputs are combined to achieve the overall high-power wideband output.
3Reliability
If an ultra-wideband isolator is used in the PA design, then the protection function is provided, but the insertion loss increases and linear indicators deteriorate
Solution Approach 1:
The wideband isolator is replaced by multiple narrowband isolators, each designed for a specific frequency band. Each narrowband isolator operates at its optimal design point, achieving effective isolation with lower insertion loss and better linear indicators compared to a single ultra-wideband isolator covering the entire frequency range.
Data Source
AI summary
A radio frequency power amplifier includes three amplification branches. Two amplification branches have narrow working frequency bands and respectively work on a frequency band A and a frequency band B. The other amplification branch works in a frequency band A and the frequency band B. The radio frequency power amplifier also includes an inter-frequency power division circuit and two circulators. The inter-frequency power division circuit performs inter-frequency power division on an output signal of a wideband amplification branch to output two paths of narrowband signals, and the two paths of narrowband signals are output after being subject to power combination with output signals of each narrowband amplification branch by the circulators.