Power Amplifier Protection Circuit for Input Power Recovery Control
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Solution Overview
Problem
Power amplifiers are prone to burnout due to large input power during the recovery of the RF path establishment, as existing overvoltage and overcurrent protection methods reduce the bias current, leading to a low gain and potential damage.
Innovation Solution
A protection circuit for power amplifiers incorporating a detection circuit, controller, and input impedance adjustment circuit, which generates control signals to adjust bias current and impedance parameters, reducing input power during protection and recovering gain to prevent burnout.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bias current is reduced to enable overvoltage or overcurrent protection, then protection is achieved, but gain of the power amplifier decreases and input power cannot be properly controlled during recovery
Solution Approach 1:
The protection function is segmented into two independent control paths: one controlling bias current through the controller, and another controlling input power through the input impedance adjustment circuit. This segmentation allows the bias current to be reduced for protection while input power is independently adjusted to maintain gain and prevent burnout during recovery.
Solution Approach 2:
The input impedance adjustment circuit acts as an intermediary between the power amplifier input and the signal source. By adjusting the input impedance, it mediates the input power level, ensuring that even when bias current is reduced, the input power remains controlled and does not cause burnout during recovery phases.
2Reliability
If bias current is reduced for protection, then overvoltage or overcurrent is prevented, but input power becomes large during recovery causing potential burnout
Solution Approach 1:
The input impedance adjustment circuit is activated in advance during the recovery process. When the controller detects that protection should be removed and begins restoring bias current, the input impedance adjustment circuit proactively adjusts the input impedance to control input power, preventing the harmful effect of large input power before it can cause burnout.
Solution Approach 2:
The controller monitors the state of the power amplifier and dynamically adjusts the input impedance adjustment circuit based on feedback. When recovery is initiated, the controller provides feedback control signals to the input impedance adjustment circuit to ensure input power is appropriately controlled, preventing burnout while restoring normal operation.
3Device complexity
If only bias current control is used for protection, then circuit complexity is minimized, but control precision over input power is insufficient
Solution Approach 1:
The input impedance adjustment circuit serves as a dedicated intermediary component specifically for controlling input power. This separate component provides precise control over input power without requiring complex control algorithms, maintaining relatively simple circuit structure while achieving high control precision.
Solution Approach 2:
The input impedance adjustment circuit changes the input impedance parameter dynamically based on operational state. By adjusting this single parameter, the circuit achieves precise control over input power levels without needing to complexly control multiple parameters simultaneously, maintaining simplicity while improving precision.
Data Source
AI summary
A protection circuit for the power amplifier includes a detection circuit, a controller and an input impedance adjustment circuit. The detection circuit is provided with an input end connected to the power amplifier and an output end connected to an input end of the controller, and is configured to detect an operation electrical signal of the power amplifier and generate a trigger electrical signal. The controller is configured to generate a first control signal and a second control signal, the first control signal is configured to control a bias current or bias voltage of the power amplifier to reduce or recover a gain of the power amplifier, and the second control signal is configured to adjust characteristic parameters of the input impedance adjustment circuit. The input impedance adjustment circuit is configured to decrease or increase input power of the power amplifier in response to the second control signal.