Power Amplifier Controller Circuit Amplitude Phase Control
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Solution Overview
Problem
Conventional RF PA control methods fail to achieve significant efficiency gains due to challenges in varying supply voltage efficiently while maintaining linearity, and they often compromise spectral occupancy performance and are not suitable for wide modulation techniques, especially with the presence of high-quality band pass filters like SAW filters.
Innovation Solution
A power amplifier controller circuit with closed amplitude and phase control loops that uses an amplitude correction signal to adjust the supply voltage and phase, employing a switched mode power supply and variable gain amplifier to optimize efficiency and reduce spectral distortion, while excluding SAW filters from the correction loop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the output transistor is biased to maintain linearity at peak power, then spectral occupancy requirements are met, but power efficiency deteriorates during off-peak periods
Solution Approach 1:
The patent implements dynamic biasing of the output transistor by adjusting the supply voltage according to the instantaneous amplitude of the RF input signal. The controller circuit continuously monitors the signal amplitude and modifies the transistor's operating point in real-time, transitioning from fixed biasing to adaptive biasing that maintains linearity only when needed while improving efficiency during low-signal periods
Solution Approach 2:
The patent changes the supply voltage parameter of the power amplifier based on the detected amplitude of the RF input signal. By varying the supply voltage dynamically, the system adjusts the transistor's operating characteristics to match the signal conditions, thereby optimizing the trade-off between linearity and power efficiency across different operating conditions
2Use of energy by moving object
If a variable power supply is used to adjust supply voltage based on amplitude signal, then power efficiency improves, but the power supply itself consumes significant power
Solution Approach 1:
The patent employs a feedback mechanism where the controller circuit detects the amplitude of the RF input signal and uses this information to adjust the supply voltage through a power supply circuit. The feedback loop ensures that the supply voltage is optimized based on actual signal conditions while minimizing unnecessary power consumption by the control system itself
Solution Approach 2:
The system uses the amplitude information from the RF input signal itself to control the power supply, rather than requiring an external control signal. The power amplifier essentially controls its own power consumption by using its input signal characteristics to regulate its supply voltage, reducing the need for additional power-hungry control circuitry
3Use of energy by moving object
If conventional EER technique is applied with large amplitude variation, then efficiency gain is achieved, but implementation complexity increases due to fast accurate voltage converter requirements
Solution Approach 1:
The patent applies partial EER by adjusting the supply voltage based on the amplitude signal but without requiring the full complexity of a fast, accurate, wide-range voltage converter. The system uses a simpler power supply circuit that provides sufficient voltage adjustment for efficiency improvement without attempting to perfectly track the amplitude signal at all frequencies and amplitudes
Solution Approach 2:
The patent changes the supply voltage parameter in response to the amplitude signal but with relaxed performance requirements compared to conventional EER. The voltage adjustment is sufficient to improve efficiency without demanding the fast switching speeds, high accuracy, and wide range that would make the voltage converter prohibitively complex
4Ease of operation
If linear regulator is used to vary voltage on fixed current load, then voltage control is achieved, but power consumption increases due to voltage drop across regulator
Solution Approach 1:
The patent transitions from static voltage control to dynamic voltage control where the supply voltage is continuously adjusted based on the RF input signal amplitude. This dynamic adjustment allows the system to operate at optimal voltage levels rather than maintaining a fixed voltage, thereby reducing power loss in the regulator while maintaining ease of voltage control
Solution Approach 2:
The patent changes the supply voltage parameter dynamically rather than maintaining a fixed voltage. By varying the voltage according to signal conditions, the system reduces the average voltage drop across the linear regulator, thereby reducing power loss while still providing effective voltage control when needed
Data Source
Figure 1~2
Figure 3A
Figure 3B
AI summary
A power amplifier controller circuit controls a power amplifier based upon an amplitude correction signal indicating the amplitude difference between the amplitude of the input signal and an attenuated amplitude of the output signal. The power amplifier controller circuit comprises an amplitude control loop and a phase control loop. The amplitude control loop adjusts the supply voltage to the power amplifier based upon the amplitude correction signal. The amplitude correction signal may also be split into two or more signals with different frequency ranges and provided respectively to different types of power supplies with different efficiencies to generate the adjusted supply voltage to the power amplifier. The phase control loop adjusts the phase of the input signal based upon a phase error signal indicating a phase difference between phases of the input signal and the output signal to reduce phase distortion generated by the power amplifier.