Asymmetric Cascaded Doherty Amplifier for Broad Power Back-Off Efficiency
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Solution Overview
Problem
Conventional power amplifiers for mobile phone base stations face challenges in maintaining high efficiency across a wide range of transmission signal power levels, particularly struggling to operate efficiently both at high and low power levels without being dependent on communication traffic variations.
Innovation Solution
The power amplifier employs a cascaded configuration of Doherty amplifiers, where each stage has a different power ratio, allowing for efficient amplification across a broader signal power range by combining asymmetric and symmetric Doherty amplifier configurations to optimize efficiency at various output power levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a conventional Doherty amplifier with symmetric configuration (same saturation output level for carrier and peak amplifiers) is used, then efficiency peaks are achieved at specific back-off points (0 dB and 6 dB), but the amplifier cannot maintain high efficiency across a wide range of transmission signal power levels
Solution Approach 1:
The patent applies asymmetry by configuring the carrier amplifier and peak amplifier with different saturation output levels. Specifically, the carrier amplifier has a higher saturation output level than the peak amplifier, creating an asymmetric Doherty amplifier structure. This asymmetric configuration allows the amplifier to maintain high efficiency across a broader range of output power levels compared to symmetric configurations, as the different saturation levels create overlapping efficiency regions that extend the high-efficiency operating range.
Solution Approach 2:
The patent employs dynamics by making the power ratio between carrier and peak amplifiers adjustable rather than fixed. The controller dynamically adjusts the power ratio based on the desired operating point and transmission signal power level. This dynamic adjustment capability allows the system to adapt to varying communication traffic conditions and maintain optimal efficiency across different operating scenarios, transforming a static symmetric design into a dynamic asymmetric system.
2Adaptability or versatility
If the saturation output level of the peak amplifier is increased to match the carrier amplifier (symmetric configuration), then efficiency peaks occur at standard back-off points, but the efficiency characteristics become dependent on specific operating points and cannot adapt to varying communication traffic
Solution Approach 1:
The patent applies parameter changes by varying the power ratio between carrier and peak amplifiers based on operating conditions. The controller adjusts the power ratio parameter to optimize efficiency for different transmission signal power levels and communication traffic patterns. This parameter adjustment mechanism allows the system to transition between different efficiency optimization modes, enabling adaptive power consumption management across varying operational requirements without being locked into a fixed symmetric configuration.
3Use of energy by moving object
If asymmetric Doherty amplifiers with different power ratios are used, then efficiency can be optimized at arbitrary operating points, but the device complexity increases due to additional control mechanisms
Solution Approach 1:
The patent applies universality by designing a controller that can handle multiple functions: adjusting power ratios, monitoring operating points, and optimizing efficiency across different scenarios. This multi-functional controller consolidates what would otherwise require multiple separate control mechanisms, reducing overall system complexity while maintaining the ability to optimize efficiency at arbitrary operating points. The universal controller serves as a single point of intelligence that manages the asymmetric Doherty amplifier's adaptive behavior.
Data Source
AI summary
A power amplifier is provided which is capable of performing efficient amplification in a wider transmission signal power range than conventional power amplifiers. The power amplifier for amplifying and outputting an input signal includes first to N-th amplifiers (N is an integer of two or more) which are cascaded. A Doherty amplifier is used in circuit configuration of each of the first to N-th amplifiers. At least one of the first to (N−1)-th amplifiers has a different power ratio from that of the N-th amplifier.