Doherty Amplifier Circuit With Impedance Bypass Against Signal Leakage
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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 power efficiency reduction, gain linearity degradation, and signal distortion due to leakage of the peak amplifier's output signal.
Innovation Solution
Incorporating a bypass route with an impedance element, such as a resistor or capacitor, to offset signal leakage from the peak amplifier to the output terminal, ensuring proper signal combination and reducing distortion.
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 signal leakage from the peak amplifier to the output terminal causes power efficiency reduction, gain linearity degradation, and signal distortion
Solution Approach 1:
The patent introduces an impedance element as an intermediary component connected between the peak amplifier output and the output terminal. This impedance element acts as a mediator to control and reduce the harmful signal leakage while allowing the peak amplifier to maintain its load impedance adjustment function. The impedance element selectively attenuates the leaked signal path without interfering with the main signal combination process.
2Power
If the peak amplifier output signal is combined with the carrier amplifier output signal, then the overall power output is increased, but non-ideal load impedance causes power efficiency reduction
Solution Approach 1:
The impedance element serves as an intermediary that prevents energy loss by blocking the leakage path from the peak amplifier to the output terminal. This allows the power combining function to operate efficiently by ensuring that only the intended signal paths contribute to the output, thereby maintaining high power efficiency while achieving the desired output power level.
3Productivity
If the peak amplifier operates at high power levels, then the overall amplifier performance is improved, but signal distortion occurs due to leakage
Solution Approach 1:
The impedance element acts as a mediator that filters out the distorted leaked signal from reaching the output terminal while allowing the main amplified signal to pass through. This enables the peak amplifier to operate at high power levels for improved productivity without introducing signal distortion, as the impedance element selectively attenuates the distortion-containing leakage path.
Data Source
AI summary
An amplifier circuit includes a carrier amplifier, a peak amplifier, a phase shift line, a power combiner that combines radio frequency signals input to a first terminal and a second terminal to obtain a combined radio frequency signal and outputs the combined radio frequency signal from a third terminal, and an impedance element that is a resistor element or a capacitor. The carrier amplifier is connected between a signal input terminal and the first terminal, the peak amplifier is connected between the signal input terminal and a first end of the phase shift line, a second end of the phase shift line is connected to the second terminal, a signal output terminal is connected to the third terminal, a first end of the impedance element is connected to the second terminal, and a second end of the impedance element is connected to the signal output terminal.