Doherty Amplifier Peak Control Using Carrier Supply Current
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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 monitoring the supply current of the carrier amplifier's transistor to rapidly adjust the peak amplifier's operation state, allowing for predictive saturation detection and rapid activation of the peak amplifier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If saturation detection is performed using a bias circuit with response time of several tens of nanoseconds, then the circuit can detect carrier amplifier saturation, but the response time is too slow to maintain high-quality output signals during instantaneous power increases
Solution Approach 1:
The patent replaces the conventional bias circuit-based saturation detection mechanism with a supply current monitoring mechanism. By monitoring the supply current of the carrier amplifier, the system achieves rapid detection of saturation conditions without the delays inherent in bias circuit response times of several tens of nanoseconds. This substitution enables the peak amplifier to be activated promptly when saturation is detected, maintaining high-quality output signals even during instantaneous power increases.
2Productivity
If the peak amplifier is activated delayed by several tens of nanoseconds during instantaneous power increase, then the carrier amplifier can operate independently at low power levels, but the output signal quality decreases during the delay period
Solution Approach 1:
The patent implements a feedback mechanism where the supply current of the carrier amplifier is continuously monitored and used to control the activation of the peak amplifier. When the supply current indicates that the carrier amplifier is approaching saturation, the feedback signal triggers immediate activation of the peak amplifier. This feedback loop eliminates the delay between saturation onset and peak amplifier activation, ensuring high output signal quality is maintained during instantaneous power increases while preserving the efficiency benefits of carrier amplifier independent operation at low power levels.
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 controls the peak amplifier based on a supply current of an amplifying transistor in the carrier amplifier.