Differential RF Power Amplifier Bias Cross-Coupling for Linearity
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Solution Overview
Problem
Advanced mobile communication systems, such as 5G, require high-efficiency RF power amplifiers that can handle high peak-to-average power ratios (PAPRs) and ultra-wideband signals, but existing techniques like envelope tracking (ET) and digital pre-distortion (DPD) are limited in providing sufficient linearity and efficiency.
Innovation Solution
A highly linear differential RF power amplifier utilizing anti-phase bias control based on cross-coupled signals, which includes multiple differential amplifier stages with bias circuits connected through cross-coupling capacitors and phase shifters to provide anti-phase bias control, reducing reliance on ET and DPD techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If envelope tracking (ET) and digital pre-distortion (DPD) techniques are used, then linearity and efficiency are improved, but device complexity and reliance on additional processing techniques increase
Solution Approach 1:
The amplifier stages perform self-linearization by using their own output signals to control their bias points. The first amplifier stage uses its output signal to control its bias point, and the second amplifier stage uses its output signal to control its bias point, eliminating the need for external ET and DPD processing techniques
Solution Approach 2:
The patent implements feedback control where the output signal of each amplifier stage is fed back to control the bias point of that same stage. This feedback mechanism automatically adjusts the operating point to maintain linearity across varying signal conditions, replacing complex external processing techniques
2Device complexity
If conventional bias control is used, then device complexity is reduced, but linearity and efficiency deteriorate under high PAPR and ultra-wideband signals
Solution Approach 1:
The patent implements dynamic bias control where the bias points of the amplifier stages are continuously adjusted based on their respective output signal levels. This dynamic adjustment maintains optimal linearity across the full power range and signal bandwidth, significantly outperforming static conventional bias control methods
Solution Approach 2:
The patent changes the operating parameters (bias points) of the amplifier stages dynamically based on signal conditions. By adjusting the bias points according to output signal levels, the amplifier maintains optimal linearity and efficiency across varying power levels and signal characteristics
Data Source
AI summary
An amplifier may include first and second terminals to receive first and second input signals and a differential amplifier providing differential amplification of the first and second input signals. The differential amplifier may include a first differential amplifier stage to receive the first input signal and a second differential amplifier stage to receive the second input signal. The amplifier may further include a first bias circuit to bias the first differential amplifier stage, where the first bias circuit is connected to the second input terminal to provide anti-phase bias control of the first differential amplifier stage. The amplifier may further include a second bias circuit to bias the second differential amplifier stage, where the second bias circuit is connected to the first input terminal to provide anti-phase bias control of the second differential amplifier stage.