Doherty Amplifier Leakage Cancellation With Auxiliary Phase Shifting
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Solution Overview
Problem
In Doherty amplifier circuits, non-ideal load impedance at the output end of the carrier amplifier leads to reduced power efficiency, gain linearity, and signal distortion due to leakage of the peak amplifier's output signal.
Innovation Solution
The inclusion of an auxiliary amplifier and phase shift circuits in the amplifier circuit configuration allows for the offsetting of the peak amplifier's signal leakage, improving power efficiency and gain linearity by ensuring the peak and auxiliary signals are phase-opposed at the output terminal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the peak amplifier operates to adjust the load impedance of the carrier amplifier output end, then the efficiency and linearity of the Doherty amplifier circuit are improved, but non-ideal load impedance causes signal leakage from the peak amplifier that reduces power efficiency, gain linearity, and increases signal distortion
Solution Approach 1:
The patent converts the harmful signal leakage from the peak amplifier into a beneficial effect by introducing an auxiliary amplifier that generates a compensating signal. This compensating signal is phase-shifted to oppose the leakage signal, thereby converting the harmful leakage into a controlled parameter that improves overall circuit performance and reduces distortion
Solution Approach 2:
The patent introduces an auxiliary amplifier as an intermediary element between the peak amplifier and the output terminal. This auxiliary amplifier generates a compensating signal that mediates the harmful interaction between the peak amplifier's leakage and the output, thereby reducing signal distortion and improving power efficiency
2Reliability
If phase shift circuits are added to offset the peak amplifier's signal leakage, then power efficiency and gain linearity are improved, but the device complexity increases
Solution Approach 1:
The auxiliary amplifier is designed to perform multiple functions simultaneously: it generates the compensating signal, provides the necessary phase shift, and outputs the combined signal. This multi-functionality reduces the need for separate dedicated components for each function, thereby managing circuit complexity while achieving the desired power efficiency improvement
Data Source
AI summary
An amplifier circuit includes a carrier amplifier connected between a signal input terminal and a signal output terminal, a peak amplifier connected between the signal input terminal and the signal output terminal, a first phase shift circuit connected between the carrier amplifier or the peak amplifier and the signal output terminal, an auxiliary amplifier connected between the signal input terminal and the carrier amplifier, and a second phase shift circuit connected between the signal input terminal and the carrier amplifier.