Power Mapping for Variable Gain Amplifier Control in GSM Transmitters
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing GSM transmitter hardware is inefficient when trying to transmit signals with both phase and amplitude modulation components due to the need for highly linear power amplifiers, which consume more power and reduce device battery life, and struggle with dynamic power control and AM to PM conversion issues.
Innovation Solution
A system that compensates for power amplifier gain control variations using a power control element, an adder, and a mapping function to combine power control signals and instantaneous envelope power references, allowing for a variable gain amplifier to adjust the power amplifier input, thereby maintaining high dynamic range control over AM signals and reducing inefficiencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a highly linear power amplifier is used to transmit combined PM and AM signals, then transmission fidelity is improved, but power consumption increases and battery life decreases
Solution Approach 1:
The patent segments the power amplifier into two distinct components: a non-linear power amplifier for efficient power amplification and a separate linear amplifier for precise gain control. This segmentation allows each component to perform its specialized function optimally - the non-linear amplifier maintains high efficiency while the linear amplifier ensures transmission fidelity for combined PM and AM signals.
Solution Approach 2:
The patent introduces a variable gain amplifier as an intermediary component between the non-linear power amplifier and the output. This intermediary handles the linear gain control requirements, allowing the main power amplifier to operate in its efficient non-linear region while still achieving the required linearity for faithful signal transmission.
2Use of energy by moving object
If a non-linear power amplifier is used to improve efficiency, then power consumption decreases, but gain control characteristics vary significantly over operation range and temperature
Solution Approach 1:
The variable gain amplifier serves as a stable intermediary that compensates for the gain control variations of the non-linear power amplifier. By placing this linear amplifier in the signal path, the system maintains consistent gain control characteristics across different operating conditions while the non-linear amplifier continues to operate efficiently.
Solution Approach 2:
The patent employs feedback mechanisms to monitor and adjust the gain control characteristics. The feedback loop detects variations in the non-linear amplifier's performance due to temperature or operating range changes and compensates through the variable gain amplifier, maintaining stable overall system characteristics.
3Measurement precision
If a closed feedback power control loop is used to control output power, then power control accuracy is improved, but the loop attenuates amplitude variations and cancels the AM portion of the signal
Solution Approach 1:
The patent segments the power control function by separating average power control from amplitude modulation. The closed feedback loop handles only the average power control, while the variable gain amplifier preserves and passes through the AM component, preventing the feedback loop from attenuating or canceling the amplitude variations.
Solution Approach 2:
The patent extracts the AM signal component from the feedback path of the power control loop. By taking out the amplitude information from the loop that controls average power, the system allows the feedback mechanism to maintain accurate power control without interfering with the AM modulation, thus preserving the amplitude variations in the output signal.
Data Source
AI summary
A system for compensating gain control variations in a power amplifier comprises a power control element configured to receive a power control signal and an instantaneous envelope power reference signal, an adder configured to combine the power control signal and the instantaneous envelope power reference signal to obtain a modified power level signal, and a mapping function configured to receive the modified power level signal and configured to alter a control input to a variable gain amplifier, the variable gain amplifier controlling an adjustable input to the power amplifier.