RF Power Amplifier Bias Circuit Reduces Current Variation
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Solution Overview
Problem
The current supply of current to power amplifiers in radio-frequency circuits is often inaccurate due to transistor process variations, leading to poor accuracy and performance, especially when used in radio-frequency circuits, with current variations as high as 20%.
Innovation Solution
A radio-frequency circuit design incorporating a power amplifier, a first bias circuit, and a second bias circuit with a current adjustment circuit using a transistor to reduce current variations, where the transistor has terminals for receiving a reference voltage and a control terminal to adjust the current provided to the power amplifier, thereby minimizing current discrepancies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bias circuit is used to supply current to the power amplifier, then the power amplifier can operate, but the current variation is as high as 20% due to transistor process variation
Solution Approach 1:
The patent implements a feedback mechanism where the bias circuit monitors the actual current supplied to the power amplifier and adjusts the bias voltage accordingly. This closed-loop control compensates for transistor process variations, reducing current variation from 20% to under 3% and significantly improving current supply accuracy.
Solution Approach 2:
The patent dynamically adjusts the bias voltage parameter based on detected current conditions. By changing the bias voltage in response to process variations, the system compensates for transistor parameter deviations and maintains stable current supply to the power amplifier.
2Measurement precision
If the current to the power amplifier is adjusted to compensate for process variation, then current accuracy improves, but the circuit complexity increases with additional bias circuits and adjustment mechanisms
Solution Approach 1:
The patent combines the bias circuit functionality with current monitoring and adjustment capabilities into an integrated system. By merging these functions, the patent achieves high current accuracy while minimizing the increase in circuit complexity through functional integration rather than adding separate independent circuits.
Solution Approach 2:
The bias circuit is designed to perform multiple functions: providing bias current, monitoring current accuracy, and adjusting bias voltage based on process variations. This multi-functionality reduces the need for separate dedicated circuits, thereby improving current accuracy without proportionally increasing circuit complexity.
Data Source
AI summary
A radio-frequency circuit can include a power amplifier, a first bias circuit and a second bias circuit. The power amplifier can include an input terminal used to receive a radio-frequency signal, and an output terminal used to output an amplified radio-frequency signal. The first bias circuit can include a first output terminal coupled to the input terminal of the power amplifier through a common node. The second bias circuit can include a second output terminal and a current adjustment circuit, where the second output terminal can be coupled to the common node, and the current adjustment circuit can include a transistor. The transistor can include a first terminal coupled to the second output terminal, a second terminal used to receive a reference voltage, and a control terminal.