Power Amplifier Bias Adjustment for Low-Voltage Current Reduction
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Solution Overview
Problem
Existing power amplifier modules consume excessive current in low power modes due to high voltage levels, and simply adjusting the number of operating unit transistors is insufficient to reduce current consumption effectively.
Innovation Solution
A power amplifier module incorporating first and second amplifiers, bias circuits, and an adjusting circuit with a transistor that adjusts bias current based on power supply voltage, allowing the transistor to operate as two p-n junction diodes at low voltages to reduce current consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the power amplifier module operates at a relatively low voltage level in low power mode, then power consumption is reduced, but current consumption cannot be sufficiently reduced merely by adjusting the number of operating unit transistors
Solution Approach 1:
The patent changes the operating parameters of the bias circuit by detecting the power supply voltage level and adjusting the bias current accordingly. When voltage drops below a threshold, the bias current is reduced proportionally, optimizing the trade-off between power consumption and signal amplification performance in low power mode
Solution Approach 2:
The patent implements a feedback mechanism where the power supply voltage is detected and used to control the bias current adjustment. The detection circuit monitors voltage levels and feeds this information to the adjustment circuit, which then modifies the bias current to maintain optimal operation across varying voltage conditions
2Power
If the number of operating unit transistors is increased to maintain amplification performance, then signal amplification capability is improved, but current consumption increases
Solution Approach 1:
The patent makes the bias current dynamic by linking it to the actual power supply voltage level. Instead of using a fixed bias current that assumes nominal voltage conditions, the system continuously adapts the bias current to match the actual operating voltage, allowing the amplifier to maintain appropriate gain while consuming less current when voltage is reduced
Data Source
AI summary
A power amplifier module includes first and second amplifiers, a first bias circuit, and an adjusting circuit. The first amplifier amplifies a first signal. The second amplifier amplifies a second signal based on an output signal from the first amplifier. The first bias circuit supplies a bias current to the first amplifier via a current path on the basis of a bias drive signal. The adjusting circuit includes an adjusting transistor having first, second, and third terminals. A first voltage based on a power supply voltage is supplied to the first terminal. A second voltage based on the bias drive signal is supplied to the second terminal. The third terminal is connected to the current path. The adjusting circuit adjusts the bias current on the basis of the power supply voltage supplied to the first amplifier.