Power Amplifier Switching Paths for Low-Output Efficiency
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Solution Overview
Problem
Conventional power amplifiers for cellular phones face inefficiencies, particularly at low to middle power operations, where reducing current consumption in control sections, including bias circuits, is necessary for improved efficiency.
Innovation Solution
A power amplifier design incorporating multiple amplifying elements, switches, a reference voltage generating circuit, and a control circuit that selectively activates and deactivates the reference voltage generating circuit based on output power levels, optimizing signal paths and reducing current consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the reference voltage generating circuit is continuously operated to maintain high accuracy reference voltage, then the reference voltage stability is improved, but the current consumption increases
Solution Approach 1:
The reference voltage generating circuit is operated periodically rather than continuously. The control circuit activates the reference voltage generating circuit only when high accuracy reference voltage is needed (during high power output modes), and stops it during low power output modes where high accuracy is not required, thereby reducing overall current consumption while maintaining reliability when needed
Solution Approach 2:
The operating state of the reference voltage generating circuit is dynamically adjusted based on the current power output mode. The control circuit changes the circuit's state (on/off) according to real-time operational requirements, making the system adaptive to different power levels and efficiency requirements
2Use of energy by moving object
If multiple amplifying elements and switches are added to optimize low power efficiency, then the efficiency in low output is improved, but the device complexity increases
Solution Approach 1:
The power amplifier is segmented into multiple parallel amplifying paths with different characteristics. Each path contains amplifying elements and switches that can be independently controlled, allowing the system to select the most efficient path for the current power level, thereby improving low power efficiency through structured division
Solution Approach 2:
The multiple amplifying elements and switches serve multiple functions: they provide different amplification paths for different power levels, enable dynamic power routing, and work together with the control circuit to implement both power level selection and reference voltage generation control, maximizing the utility of each component
Data Source
AI summary
A power amplifier includes: a first amplifying element amplifying an input signal; a second amplifying element amplifying an output signal of the first amplifying element; a third amplifying element amplifying the input signal; a first switch connected between an output of the first amplifying element and an input of second amplifying element; a second switch connected between an output of the first amplifying element and an output of the third amplifying element; a third switch connected between an output of the first amplifying element and an output of the second amplifying element; a reference voltage generating a circuit generating reference voltage; a bias circuit supplying a bias current, based on the reference voltage, to inputs of the first, second, and third amplifying elements; and a control circuit controlling the first, second and third switches and the reference voltage generating circuit.