Doherty Amplifier Peak Control for Fast Saturation Response
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Solution Overview
Problem
Existing Doherty amplifier circuits face challenges in maintaining high-quality high-frequency output signals due to slow response times in detecting saturation, leading to inefficiencies and decreased communication quality, especially when dealing with instantaneous power increases.
Innovation Solution
A Doherty amplifier circuit configuration that includes a carrier amplifier, a peak amplifier, and a control circuit capable of rapidly detecting the drive level of the carrier amplifier using a current monitoring circuit and drive level detection circuit to control the peak amplifier, allowing for faster activation and maintaining high-frequency signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bias circuit with several tens of nanoseconds response time is used to detect carrier amplifier saturation, then the circuit can control the peak amplifier bias, but the response time is too slow to maintain high-frequency output signal quality during instantaneous power increases
Solution Approach 1:
The patent replaces the conventional bias circuit detection method with a direct electrical detection method using a detection circuit that monitors the carrier amplifier's input signal. This substitution eliminates the mechanical/electrical inertia of traditional bias circuits, achieving instantaneous response to saturation conditions without the several tens of nanoseconds delay, thereby maintaining high-frequency output signal quality during rapid power transitions.
Solution Approach 2:
The patent introduces a detection circuit as an intermediary between the carrier amplifier and peak amplifier control. This intermediary directly monitors the carrier amplifier's input signal and immediately reflects saturation status to control the peak amplifier bias, bypassing the slow response characteristic of conventional bias circuits and enabling real-time adaptation to power level changes.
2Reliability
If the Doherty amplifier circuit uses conventional saturation detection methods, then the peak amplifier bias can be controlled, but communication quality deteriorates due to slow response to power level changes
Solution Approach 1:
The detection circuit continuously monitors the carrier amplifier's input signal in advance, detecting saturation conditions before they significantly impact output quality. This preliminary detection enables the peak amplifier bias to be adjusted proactively, preventing communication quality deterioration rather than reacting after the fact.
Solution Approach 2:
The patent implements a direct feedback mechanism where the detection circuit monitors the carrier amplifier's input signal and immediately adjusts the peak amplifier bias accordingly. This real-time feedback loop ensures that communication quality is maintained by continuously adapting to power level changes without the time loss associated with conventional detection methods.
Data Source
AI summary
A Doherty amplifier circuit includes a carrier amplifier that amplifies a high frequency signal, a peak amplifier that amplifies the high frequency signal, and a control circuit that detects a drive level of the carrier amplifier with reference to a detection result of an input signal of the carrier amplifier and controls the peak amplifier based on a detection result.