Multi-Stage RF Power Amplifier Feedback for Stable Output Power
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Solution Overview
Problem
Radio frequency power amplifiers in wireless communication terminals face instability due to process deviations and temperature variations, leading to fluctuations in gain and output power, which are exacerbated by variations in input signals, necessitating effective feedback control mechanisms to maintain stable operation.
Innovation Solution
A radio frequency power amplifier employing multiple stages of amplifier circuits with current detection feedback circuits that generate control voltages inversely proportional to quiescent operating currents, and power detection feedback circuits that adjust currents based on detected output power, ensuring stable gain and output power by compensating for variations caused by process deviations and input signal changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If feedback control is implemented to stabilize gain and output power, then stability of gain and output power is improved, but device complexity increases due to additional feedback circuits
Solution Approach 1:
The patent implements feedback control by detecting the quiescent operating current of the current amplifier stage and feeding back a control signal to previous stages. The current detection feedback circuit monitors the actual operating current and adjusts the base voltage of previous stages to compensate for deviations, thereby stabilizing the gain and output power despite process variations and temperature changes.
Solution Approach 2:
The patent introduces a current detection feedback circuit as an intermediary component that mediates between the amplifier stages. This circuit detects the quiescent operating current and generates a control signal that acts as an intermediary adjustment mechanism, allowing stable operation without requiring complex direct control of each stage.
2Reliability
If current detection feedback circuit is added to stabilize operating state, then reliability is improved, but manufacturing precision requirements increase due to additional circuit components
Solution Approach 1:
The current detection feedback circuit creates a copy of the quiescent operating current signal for detection and feedback purposes. By copying the current signal rather than directly measuring complex parameters, the circuit simplifies the detection process and reduces the precision requirements for manufacturing components while maintaining reliability.
3Productivity
If multiple stages of amplifier circuits are used to achieve required gain, then productivity is improved, but stability deteriorates due to cumulative effects of process deviation and temperature variation
Solution Approach 1:
The patent applies feedback control across multiple amplifier stages by detecting the quiescent operating current at the current stage and feeding back control signals to previous stages. This distributed feedback mechanism compensates for cumulative deviations in each stage, maintaining stability while preserving the high gain capability of multi-stage amplification.
Solution Approach 2:
The patent segments the feedback control function across multiple amplifier stages, with each stage having its quiescent operating current detected and fed back to appropriate previous stages. This segmentation allows independent optimization of each stage while maintaining overall system stability through coordinated feedback control.
Data Source
AI summary
Disclosed in the present invention are a radio frequency power amplifier based on current detection feedback and a chip. The radio frequency power amplifier comprises multiple stages of amplifier circuits and at least one current detection feedback circuit; the input end of the current detection feedback circuit is connected to the input end of a current stage of amplifier circuit among the multiple stages of amplifier circuits by means of a corresponding resistor, and the output end of the current detection feedback circuit is connected to the input end of at least one stage of amplifier circuit prior to the current stage of amplifier circuit. The current detection feedback circuit generates, according to the detected quiescent operating current of the current stage of amplifier circuit, a control voltage varying inversely with the quiescent operating current, so that the current detection feedback circuit outputs current varying positively with the control voltage.