Variable Bias Impedance for Power Amplifier Gain and Phase Control
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Solution Overview
Problem
Existing power amplifier systems face challenges in managing RF signal amplification, as incorrect amplification levels or distortion can cause devices to transmit out of band or violate compliance standards, highlighting the need for improved power amplifier biasing techniques.
Innovation Solution
A power amplifier system with a bias circuit and a bias impedance component that adjusts impedance values based on control signals to optimize gain characteristics, including a method for generating a bias signal and adjusting impedance to improve power amplifier performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a fixed bias impedance is used in the power amplifier, then the circuit is simple, but the gain characteristics and linearity cannot be optimized for different operating conditions
Solution Approach 1:
The patent applies the dynamics principle by making the bias impedance variable rather than fixed. A voltage-controlled resistor (VCX) is used to dynamically adjust the bias impedance based on control voltage, allowing the power amplifier to optimize its gain characteristics and linearity for different operating conditions while maintaining a relatively simple circuit structure.
2Power
If the bias voltage is increased to improve amplification, then the output power increases, but distortion increases and compliance standards may be violated
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the bias impedance rather than simply increasing bias voltage. By changing the impedance parameter of the bias circuit, the power amplifier can achieve higher output power while maintaining signal linearity and avoiding distortion that would violate compliance standards.
3Ease of manufacture
If the bias circuit is simplified to reduce complexity, then the device is easier to manufacture, but the ability to control gain and maintain linearity is reduced
Solution Approach 1:
The patent uses a voltage-controlled resistor (VCX) as an intermediary element between the bias voltage source and the power amplifier stage. This intermediary component allows for precise control of the bias impedance and gain characteristics while keeping the overall circuit structure simple and easy to manufacture. The VCX translates voltage control into precise impedance adjustment.
Data Source
AI summary
Systems and methods including variable power amplifier bias impedance are disclosed. In one aspect, there is provided a power amplifier system including a bias circuit configured to receive a bias voltage and generate a bias signal and a power amplifier stage configured to receive an input radio frequency (RF) signal and generate an output RF signal. The power amplifier system may also include a bias impedance component operatively coupled between the bias circuit and the power amplifier stage. The bias impedance is component configured to receive a control signal and adjust an impedance value of the bias impedance component in response to the control signal.