Transistor-Based Power Amplifier Biasing Without Large Resistors
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Solution Overview
Problem
The miniaturization of power amplifiers for mobile devices is hindered by the use of large resistors required to control current, which occupy significant chip/die area and limit design flexibility.
Innovation Solution
The implementation of a power amplifier circuit using transistors instead of large resistors to control current, with a current source, current mirror, and power control circuits that include transistors to generate and regulate currents, allowing for reduced chip area and increased design flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If large resistors are used to control current in the power amplifier, then precise current control is achieved, but chip/die area increases
Solution Approach 1:
The patent changes the fundamental parameter from using passive resistive elements to active transistor-based current control. By using transistors in the bias circuit (particularly the current mirror configuration with transistors Q1-Q4), the circuit achieves precise current control through active device characteristics rather than passive resistance values, thereby reducing the area required while maintaining control precision.
Solution Approach 2:
The patent replaces the traditional resistive current control mechanism with a transistor-based electronic control mechanism. The current mirror circuit using transistors substitutes for the large resistor-based current limiting approach, enabling more efficient use of chip area while maintaining precise current regulation through the transistor's current amplification and mirroring properties.
2Measurement precision
If large resistors are used to control current, then current precision is maintained, but design flexibility is reduced
Solution Approach 1:
The patent introduces dynamic control capability through the transistor-based bias circuit. The use of transistors Q1-Q4 in the current mirror and bias generation allows for dynamic adjustment of current levels and operational modes, providing design flexibility that static resistor-based circuits cannot achieve. The circuit can adapt to different operating conditions and power levels dynamically.
Solution Approach 2:
The transistor-based bias circuit serves multiple functions: it generates bias currents, mirrors currents between different stages, and provides adjustable current control. This multi-functional capability replaces what would otherwise require multiple separate components in a resistor-based design, thereby increasing design flexibility and adaptability.
3Area of stationary object
If transistors are used instead of large resistors, then chip area is reduced, but circuit complexity increases
Solution Approach 1:
The patent merges multiple functions into the transistor-based bias circuit. The current mirror configuration combines current generation, current regulation, and current distribution functions into a single integrated circuit block using transistors Q1-Q4, rather than requiring separate resistors and control circuits. This consolidation reduces overall chip area while the modular transistor configuration keeps the complexity manageable.
Data Source
AI summary
The present disclosure relates to a power amplifier circuit including a current source, a power control circuit, a current mirror and an output circuit. The current source circuit includes a first transistor and a second transistor. A source of the first transistor is connected to a drain of the second transistor and a gate of the first transistor is connected to a source with the second transistor. The power control circuit is connected to a gate of the second transistor. The current mirror circuit is connected to the gate of the first transistor and a source of the second transistor. The output circuit is connected to the current mirror circuit.