Dual Digital Power Amplifier With Phase-Adjusted Output Combining
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Solution Overview
Problem
Power amplifiers in wireless communications devices face a tradeoff between efficiency and linearity, where high efficiency is achieved at maximum output power but at the cost of nonlinearity, which is problematic for signals with large peak-to-average ratios (PAR) as it reduces efficiency and may violate spectral mask regulations.
Innovation Solution
A power amplifier system using two digital amplifiers, where one processes the amplitude and phase information of a digital signal to generate an analog output, and the other adjusts the signal to control the relationship between the outputs, allowing for improved efficiency and linearity by combining their signals, thereby extending linear operation beyond saturation points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the power amplifier operates at maximum output power to achieve high efficiency, then efficiency is improved, but linearity deteriorates causing nonlinearity and spectral mask violations
Solution Approach 1:
The power amplifier is divided into two separate digital amplifiers operating in parallel. The first digital amplifier handles the fundamental signal component while the second digital amplifier processes the adjusted signal component. This segmentation allows each amplifier to operate in its optimal region, with the first providing linear amplification and the second compensating for saturation effects, thereby resolving the contradiction between efficiency and linearity.
Solution Approach 2:
The outputs of the two digital amplifiers are combined through a combiner to produce the final amplified signal. By merging the linear component from the first amplifier with the saturation-compensated component from the second amplifier, the system achieves both high efficiency (from operating near saturation) and maintained linearity (from the combined output), resolving the technical contradiction.
2Manufacturing precision
If the power amplifier operates well under peak power to maintain linearity for high PAR signals, then linearity is improved, but efficiency deteriorates significantly
Solution Approach 1:
The signal processing function is segmented between two digital amplifiers. The first amplifier operates linearly to preserve signal fidelity, while the second amplifier is adjusted to operate near saturation and provide the necessary power boost. This segmentation enables the system to achieve high efficiency without sacrificing linearity, as each amplifier performs its specialized function optimally.
Solution Approach 2:
The system changes the operating parameters of the two amplifiers differently - the first amplifier maintains linear operating parameters while the second amplifier operates with saturated parameters. By adjusting the amplitude and phase of the input signals to each amplifier, the system achieves both high efficiency and linearity simultaneously, resolving the contradiction between operating under peak power and maintaining linearity.
3Device complexity
If a single digital amplifier is used to process the digital input signal, then device complexity is reduced, but the ability to simultaneously achieve high efficiency and linearity deteriorates
Solution Approach 1:
Rather than using a single complex amplifier trying to achieve both linearity and efficiency, the system segments the amplification function into two simpler digital amplifiers. Each amplifier has a simplified design with a specific function, making the overall system easier to implement while achieving superior performance in both efficiency and linearity simultaneously.
Solution Approach 2:
The system combines the outputs of two digital amplifiers to achieve performance that neither amplifier could achieve alone. This merging approach allows the system to overcome the limitations of a single amplifier design, achieving both high efficiency and linearity without requiring either amplifier to be overly complex.
Data Source
AI summary
Systems and methods for power amplification using multiple digital amplifiers are provided. A power amplifier includes a first digital amplifier configured to process a digital input signal to generate a first analog output signal. The first analog output signal is configured to have a magnitude corresponding to amplitude information of the digital input signal. The power amplifier further includes a second digital amplifier configured to process an adjusted digital input signal to generate a second analog output signal. The second analog output signal is configured to have a magnitude corresponding to amplitude information of the adjusted digital input signal. An adjustment module configured to adjust amplitude information and phase information of the digital input signal generates the adjusted digital input signal. The digital input signal is adjusted to control a relationship between the first analog output signal and the second analog output signal.