Power Amplifier Dynamic Bias Delay Synchronization
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Solution Overview
Problem
Dynamic bias misalignment in power amplifiers leads to interference with signal synchronization, causing undesired emissions and poor transmission quality in radio transmitters, especially when the power amplifier is changed, requiring manual adjustment of cable length for proper delay.
Innovation Solution
A dynamic bias synchronization system using an adaptive predistortion controller and intelligent bias control block, which employs early-late cross-correlation techniques and digital fractional delay filters to synchronize the dynamic bias signal with the transmission signal, ensuring alignment without interfering with predistortion synchronization, and utilizing a frequency selective power meter to optimize signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If manual cable length adjustment is used to provide fixed delay for bias signal synchronization, then the bias signal can be aligned with the input signal, but the system becomes difficult to adjust when power amplifier is changed and requires manual recalibration
Solution Approach 1:
The patent implements dynamic bias signal delay adjustment through a control system that automatically modifies the delay parameter based on detected signal characteristics. Instead of using a fixed cable length for delay, the system employs a variable delay element controlled by a microprocessor that continuously adapts the delay value to maintain synchronization between the bias signal and the RF input signal, eliminating manual adjustment requirements.
Solution Approach 2:
The patent uses a feedback mechanism where the system detects the phase relationship between the bias signal and the RF input signal, compares it against the desired synchronization condition, and automatically adjusts the bias signal delay parameter accordingly. This closed-loop control ensures continuous synchronization without requiring manual intervention when power amplifiers are changed.
2Use of energy by moving object
If dynamic biasing is applied to increase power efficiency, then power consumption is reduced, but bias signal misalignment causes interference with signal synchronization resulting in undesired emissions
Solution Approach 1:
The patent implements a feedback control system that continuously monitors the synchronization between the dynamic bias signal and the RF input signal. When misalignment is detected, the system automatically adjusts the bias signal delay parameter to restore proper synchronization, thereby eliminating the undesired emissions that would otherwise result from bias misalignment while preserving the power efficiency benefits of dynamic biasing.
Solution Approach 2:
The patent replaces manual mechanical adjustment of bias signal timing with an electronic control system that uses digital signal processing and microprocessor-based control to automatically synchronize the dynamic bias signal with the RF input signal, eliminating the need for physical cable length adjustments and preventing emission issues.
3Adaptability or versatility
If fixed delay is provided by cable length, then the bias signal delay is determined, but changing the power amplifier requires finding a new cable length to obtain proper delay
Solution Approach 1:
The patent replaces the static fixed delay approach using cable length with a dynamic electronic delay control system. The system includes a variable delay element controlled by a microprocessor that can electronically adjust the bias signal delay parameter to match different power amplifier characteristics, enabling easy amplifier interchangeability without requiring physical cable changes or complex calibration procedures.
Solution Approach 2:
The patent changes the delay parameter from a fixed physical property (cable length) to a controllable electrical parameter that can be dynamically adjusted through software control. The microprocessor-based system modifies the bias signal delay parameter based on detected amplifier characteristics, allowing the system to adapt to different power amplifiers without requiring physical reconfiguration or complex calibration.
Data Source
AI summary
A power amplifier system includes a nonlinear power amplifier that receives a predistorted input signal. A receiver receives an output signal from the power amplifier and provides an observed signal. A bias controller provides a delayed dynamic bias signal to the power amplifier wherein the bias signal delay is dynamic and is a function of the observed signal for synchronizing the predistorted input signal with the dynamic bias signal. A method is also described that alternately adjusts predistortion delays and bias signal delays as a function of observed signals.