Closed Loop Power Control System for Wireless Transmitters
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Solution Overview
Problem
Modern wireless communications devices face challenges in maintaining accurate power level control due to varying operating conditions, leading to issues such as excessive noise interference and transmission errors, especially when using open loop power control methods that fail to meet stringent performance requirements of complex modulation schemes like EDGE and WCDMA.
Innovation Solution
A closed loop power control system is implemented, comprising a feed forward unit, feedback unit, closed loop power control unit, and ramp path power control unit, which processes signals, generates correction signals, and adjusts output power levels dynamically to meet changing requirements, using a regulated control algorithm and algorithmic layers for parameter-based compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If open loop power control is used, then device complexity is reduced, but power level accuracy deteriorates
Solution Approach 1:
The patent implements a closed-loop power control system that uses feedback from a power detector to continuously monitor the actual output power level and compare it with the desired power level. Based on the error signal, the system dynamically adjusts the power control parameters to maintain accurate power levels despite variations in operating conditions such as temperature, battery voltage, and load impedance.
2Measurement precision
If closed loop power control is implemented, then power level accuracy is improved, but device complexity increases
Solution Approach 1:
The closed-loop power control system is designed to be self-regulating, automatically adjusting power levels based on feedback without requiring external intervention. The system monitors its own output power through the feedback unit and self-corrects any deviations from the desired power level, making the complexity management inherent to the system's operation rather than requiring additional external control mechanisms.
3Ease of manufacture
If calibrated power levels are used, then initial setup is simplified, but adaptability to varying operating conditions deteriorates
Solution Approach 1:
The patent transitions from static calibrated power levels to dynamic power control that continuously adapts to changing operating conditions. The system uses real-time feedback to detect variations in temperature, battery voltage, and load impedance, and dynamically adjusts the power output accordingly. This dynamic approach maintains power level accuracy across varying conditions while preserving the benefits of initial calibration through the feed-forward unit.
4Loss of time
If abrupt power level changes are made, then time efficiency is improved, but spectral requirements compliance deteriorates
Solution Approach 1:
The patent implements a ramping profile mechanism that performs preliminary power adjustment before actual transmission begins. The feed-forward unit generates a ramping signal that gradually increases or decreases power levels according to a predetermined profile, ensuring that power transitions meet spectral requirements while minimizing the time spent in intermediate power states. This preliminary ramping action prevents abrupt changes that would cause spectral regrowth.
Data Source
AI summary
A power control loop includes a feed forward unit 301 coupled to a data source, the feed forward unit 301 processes a signal for transmission, a feedback unit 302 coupled to the feed forward unit 301, the feedback unit 302 generates a feedback signal representative of an output power level of the signal transmitted by the feed forward unit 301, a closed loop power control unit 303 coupled to the feedback unit 302 and to the feed forward unit 301, the closed loop power control unit 303 generates an additive correction signal based on an error signal computed from the feedback signal and data provided by the data source, and a ramp path power control unit 304 coupled to the data source, the ramp path power control unit 304 generates a multiplicative correction signal based on an additive correction signal and data provided by the data source.