Doherty Power Amplifier Source Potential Control
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Solution Overview
Problem
Doherty-type power amplifiers for base stations face significant power loss due to phase differences between the main and auxiliary amplifiers when the auxiliary amplifier is activated at high output power, requiring complex and costly bias control circuits to manage gate biases effectively.
Innovation Solution
A power amplifier configuration that includes a control circuit between the main amplifier's source and ground, using a resistance element and optionally a capacitative element to adjust the source potential and reduce phase differences by minimizing the difference in gate-to-source voltages between the main and auxiliary amplifiers, thereby simplifying the circuit and reducing power loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If gate biases of main amplifier and auxiliary amplifier are controlled according to input power to reduce power combination loss, then power combination loss is reduced, but circuit complexity increases due to requiring orthogonal splitter, detector, and bias control circuit
Solution Approach 1:
The invention extracts and eliminates the complex bias control circuitry (orthogonal splitter, detector, and bias control circuit) from the system by using a simplified approach where the auxiliary amplifier's gate bias is directly controlled by the input signal without requiring additional control components. This removes the problematic elements while maintaining the essential function of reducing power combination loss.
Solution Approach 2:
The input signal serves multiple functions simultaneously: it directly drives the auxiliary amplifier's gate bias control and also serves as the signal to be amplified. This multi-functionality eliminates the need for separate bias control circuits and reduces overall system complexity while achieving the desired power combination improvement.
2Power
If auxiliary amplifier is turned on to start amplification at high output power, then high power amplification is achieved, but phase difference between auxiliary amplifier and main amplifier causes large power combination loss
Solution Approach 1:
The invention changes the gate bias parameter of the auxiliary amplifier dynamically based on the input signal level. By adjusting the gate bias according to input power, the auxiliary amplifier's operating point is optimized to reduce phase difference with the main amplifier, thereby minimizing power combination loss while maintaining high output power capability.
Data Source
AI summary
A power amplifier includes a main amplifier, an auxiliary amplifier, and a control circuit. The main amplifier is configured to amplify input power, and the auxiliary amplifier is configured to amplify the input power when the input power exceeds a certain level. The control circuit, which is provided between a source of the main amplifier and a ground, is configured to control a source potential of the main amplifier so as to increase the source potential when the input power reaches at least a certain value.