Phase Detector Offset Switching for Stable RF Amplifier Correction

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Solution Overview

Problem

Existing power amplifiers for portable communication devices face inefficiencies when switching between constant and non-constant envelope modulation methods, leading to increased power consumption and instability, particularly in GSM and EDGE communication formats, due to phase distortion and the need for accurate phase correction in closed-loop polar modulation systems.

Innovation Solution

A phase detector is implemented in a phase correction feedback loop that selects the closest phase offset from multiple detectors to minimize initial phase change, using a switch to enable the phase correction loop with reduced phase shift requirements, thereby stabilizing the power amplifier output and maintaining efficient operation across different modulation modes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a linear power amplifier is used for non-constant envelope modulation (EDGE), then the amplifier can handle amplitude and phase modulated waveforms, but power consumption increases significantly

Engineering Contradiction:

Improvemodulation compatibilityVSAvoidpower consumption

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The patent implements a dynamic modulation scheme where the power amplifier operates in nonlinear mode with corrective feedback. The system dynamically adjusts the input signal to the power amplifier by pre-distorting it based on measured output characteristics, allowing a nonlinear amplifier to effectively handle non-constant envelope modulations like EDGE while maintaining power efficiency.

Inventive Principle:

Principle #15Dynamics

2Use of energy by moving object

If a nonlinear power amplifier is used for constant envelope modulation (GSM), then power efficiency is maintained, but the amplifier cannot properly handle non-constant envelope modulations (EDGE)

Engineering Contradiction:

Improvepower efficiencyVSAvoidmodulation compatibility

Core Design Contradiction:

Use of energy by moving objectVSAdaptability or versatility

Solution Approach 1:

The patent employs a feedback mechanism where the output of the nonlinear power amplifier is measured and compared with the desired output. The error signal is used to adjust the input signal through pre-distortion, creating an effective linearization of the nonlinear amplifier. This allows the amplifier to maintain power efficiency while handling non-constant envelope modulations.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system performs preliminary pre-distortion of the input signal before it reaches the power amplifier. By anticipating the nonlinear characteristics of the amplifier and pre-compensating the input signal, the system ensures that the final output matches the desired waveform, enabling the nonlinear amplifier to handle complex modulations effectively.

Inventive Principle:

Principle #10Preliminary action

3Use of energy by moving object

If closed-loop polar modulation is implemented with feedback, then power amplifier efficiency is improved, but phase distortion and instability occur due to inaccurate phase detection

Engineering Contradiction:

Improvepower amplifier efficiencyVSAvoidphase accuracy

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent segments the phase detection function into multiple parallel phase detectors, each tuned to detect phase at different reference points. This segmentation allows the system to select the most accurate phase detection result based on current operating conditions, improving overall phase accuracy and system reliability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system dynamically changes detection parameters by selecting different phase detector outputs based on operating conditions. The switch mechanism allows selection of phase detector results with different phase offsets, enabling the system to adapt to varying phase distortion characteristics and maintain accurate phase detection across different modulation modes.

Inventive Principle:

Principle #35Parameter changes

4Measurement precision

If multiple phase detectors are used to improve phase detection accuracy, then phase accuracy improves, but device complexity increases

Engineering Contradiction:

Improvephase detection accuracyVSAvoidphase detector configuration

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent implements a dynamic selection mechanism where a switch chooses between multiple phase detector outputs based on current operating conditions. This dynamic approach allows the system to use multiple detectors for improved accuracy when needed, while simplifying operation through automated selection, effectively managing the trade-off between precision and complexity.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS7904045B2Phase detector comprising a switch configured to select a phase offset closest to a phase of an amplifier

Publication Date: 2011.03.08 AXIOM MICRODEVICES INC

AI summary

A phase detector includes a plurality of phase detectors located in a phase correction loop, each phase detector configured to receive as input a radio frequency (RF) input signal and an RF reference signal, each of the plurality of phase detectors also configured to provide a signal representing a different phase offset based on the phase difference between the RE input signal and the RF reference signal; and a switch configured to receive an output of each of the plurality of phase detectors and configured to select the output representing the phase offset, that is closest to a phase of an output of an amplifier.