Power Amplifier Bias Circuit With Parallel Bias Paths for Linearity
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Solution Overview
Problem
Existing bias circuits for power amplifiers suffer from nonlinear effects and memory effects, leading to deteriorated linearity performance, particularly in MOS transistor amplifiers.
Innovation Solution
A bias circuit design comprising a first and second part circuit connected in parallel, with each providing bias voltages that superimpose to create a stable bias voltage, and an impedance within a preset range, using transistors, resistors, and capacitors to adjust and stabilize the gate voltage of the power amplifier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional bias circuit is used for power amplifier, then the circuit structure is simple, but the linearity performance deteriorates due to nonlinear effects and memory effects
Solution Approach 1:
The bias circuit is divided into two separate part circuits connected in parallel. Each part circuit provides a bias voltage component, and their combined effect produces the desired stable bias voltage with improved linearity. This segmentation allows each sub-circuit to be optimized for specific functions, reducing overall nonlinear effects while maintaining manageable complexity.
2Reliability
If the bias voltage is adjusted to improve linearity, then the linearity performance improves, but the bias stability deteriorates
Solution Approach 1:
The circuit uses variable resistors and variable capacitors that can be adjusted to optimize performance. By changing the resistance and capacitance parameters, the circuit achieves both improved linearity and maintained bias stability. The parallel configuration of two part circuits allows independent parameter adjustment to balance linearity and stability requirements.
3Reliability
If the impedance of bias circuit is not controlled, then the circuit design is flexible, but the memory effects increase
Solution Approach 1:
The patent specifies that the impedance of the bias circuit should be within a preset impedance range. This parameter control is achieved through the careful selection and adjustment of resistive and capacitive elements in the parallel part circuits. By controlling the impedance parameter within specified bounds, memory effects are reduced while the design remains practical.
Data Source
AI summary
A bias circuit of a power amplifier includes a first part circuit, a second part circuit and a power supply, in which the power supply is connected with a power supply end of the first part circuit; two ends of the first part circuit are connected in parallel with two ends of the second part circuit, and after parallel connection one end of a parallel circuit is connected with a gate of the first transistor of the power amplifier in a signal amplification circuit; the first part circuit is configured to provide a first bias voltage, and the second part circuit is configured to provide a second bias voltage; the two bias voltages are superimposed to provide a stable bias voltage; and an impedance of the bias circuit is in a preset range of the impedance.