Variable RF Amplifier Chain With Attenuation for Low Noise Output
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Solution Overview
Problem
Current wireless communication systems face challenges in minimizing noise and distortion in RF power amplifiers, which affect the signal-to-noise ratio and overall performance, especially in varying transmit power scenarios.
Innovation Solution
A controlled power amplifier system comprising a variable-gain preamplifier, a fixed-gain power amplifier, and a variable attenuator, where the gain and attenuation are adjusted to minimize noise and distortion, using preamplifier and attenuator control signals to optimize the signal-to-noise ratio and achieve desired amplification levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single variable-gain power amplifier is used to achieve variable transmit power, then the device complexity is reduced, but the noise and distortion increase affecting the signal-to-noise ratio
Solution Approach 1:
The patent divides the amplification function into two separate stages: a fixed-gain power amplifier and a variable-gain preamplifier. The fixed-gain power amplifier handles the majority of amplification with high efficiency, while the variable-gain preamplifier provides fine-tuned variable gain control with lower noise. This segmentation allows each amplifier to operate in its optimal performance range, reducing overall noise and distortion while maintaining variable transmit power capability.
2Use of energy by moving object
If the preamplifier gain is reduced to achieve lower transmit power, then the power consumption is reduced, but the noise performance deteriorates
Solution Approach 1:
The patent implements dynamic gain control where the variable-gain preamplifier can independently adjust its gain level based on the desired transmit power. This dynamic adjustment allows the system to maintain optimal noise performance across the entire power range by keeping the preamplifier gain above a minimum threshold while using the attenuator to achieve power reduction, rather than simply reducing preamplifier gain which would increase noise.
3Device complexity
If a variable-gain power amplifier is used to achieve desired output power levels, then the device complexity is reduced, but the linearity and signal-to-noise ratio worsen
Solution Approach 1:
The patent assigns different functional qualities to different parts of the amplification chain. The fixed-gain power amplifier is optimized for high-power operation with high linearity and efficiency, while the variable-gain preamplifier is optimized for low-noise operation with precise gain control. The attenuator provides clean power reduction without adding noise. This local optimization of each component's quality ensures overall high signal-to-noise ratio and linearity while maintaining variable power capability.
Data Source
AI summary
A fixed-gain power amplifier receives a preamplifier output signal and produces a power output signal. The preamplifier output signal is amplified by the fixed-gain power amplifier to produce the power output signal. The variable-gain preamplifier receives an input signal, a preamplifier control signal, and produces the preamplifier output signal. The input signal is amplified by a preamplifier amount of gain by the variable-gain preamplifier to produce the preamplifier output signal. The preamplifier amount of gain is based on the preamplifier control signal. A variable attenuator receives the power output signal, an attenuator control signal, and produces an output signal. The power output signal is attenuated by an attenuator amount of attenuation by the variable attenuator to produce the output signal. The attenuator amount of attenuation is based on the attenuator control signal.