Push-Pull PA Output Matching Circuit for Parasitic Inductance Loss
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Solution Overview
Problem
The performance of existing power amplifiers is significantly influenced by load line impedance and insertion loss, which limits the maximum output power and power conversion efficiency.
Innovation Solution
A PA output matching circuit is introduced, featuring a load balun, DC blocking circuits, and feed circuits, which connect the first and second PA outputs of a push-pull PA. This configuration helps eliminate the effects of parasitic inductance on load line impedance and insertion loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If load line impedance is reduced to improve maximum output power, then output power is improved, but power conversion efficiency deteriorates
Solution Approach 1:
The patent segments the load line into multiple adjustable impedance sections using switched capacitor networks. By dividing the load line into discrete segments that can be independently controlled, the system can optimize different portions of the signal cycle separately, achieving high output power while maintaining efficiency through selective impedance tuning in different operating regions.
Solution Approach 2:
The patent implements dynamic load line adjustment by switching between different impedance configurations during operation. The load line impedance is made variable rather than fixed, allowing the system to adapt impedance values in real-time based on operating conditions. This dynamic tuning enables the power amplifier to maintain optimal efficiency across different output power levels while achieving maximum output power when needed.
2Power
If load line impedance is continuously reduced to achieve greater output power, then output power increases, but load line insertion loss worsens
Solution Approach 1:
The patent changes the impedance parameters of the load line by switching between different capacitor configurations. By adjusting capacitance values and connections in the switched capacitor network, the system transforms the load line characteristics to achieve desired output power levels while controlling insertion loss. This parameter transformation allows optimization of both power output and signal integrity.
3Device complexity
If traditional PA output matching circuit is used, then circuit simplicity is maintained, but performance is significantly influenced by parasitic inductance
Solution Approach 1:
The patent introduces a DC blocking capacitor as an intermediary element in the output matching circuit. This capacitor acts as a mediator that blocks DC components while allowing AC signals to pass, thereby isolating the effect of parasitic inductance from the main signal path. The DC blocking capacitor serves as a buffer that prevents parasitic inductance from degrading performance while maintaining overall circuit simplicity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed solution effectively improves the output power and power conversion efficiency of the push-pull PA by minimizing the impact of parasitic inductance on load line characteristics.
Implementation Method 1
a first DC blocking circuit and a first feed circuit are respectively connected in parallel between a first PA output of an output stage of the push-pull PA and a first balun input of the load balun to transmit AC signals and DC signals respectively
Implementation Method 2
the second DC blocking circuit is configured to resonate with an inductor at a working frequency band
Data Source
AI summary
Provided are a PA output matching circuit, a RF front-end module and a wireless device. The circuit is used for connecting with a first PA output and a second PA output of an output stage of a push-pull PA, and comprises a load balun, a first DC blocking circuit, a second DC blocking circuit, a first feed circuit and a second feed circuit; the main coil of the load balun is provided with a first balun input and a second balun input; the first balun input is connected with the first PA output via the first DC blocking circuit, and the first balun input is connected with the first PA output via the first feed circuit; the second balun input is connected with the second PA output via the second DC blocking circuit, and the second balun input is connected with the second PA output via the second feed circuit.