Polar Transmitter FM Path With Limited Frequency Deviation
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Solution Overview
Problem
Conventional polar transmitters experience peak frequency issues and increased complexity in their digital controlled oscillators due to large frequency deviations, leading to nonlinearity problems and degraded performance.
Innovation Solution
A transmitter with a phase/frequency deviation input, controller, and frequency modulating path that limits phase variation to a specific range, using a phase swapper to select phases and perform frequency modulation, thereby reducing frequency deviation and simplifying the phase-locked loop circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If wide bandwidth is used in the polar transmitter, then the frequency coverage is improved, but peak frequency occurs and the DCO design complexity increases
Solution Approach 1:
The transmitter is divided into separate AM and FM paths that operate independently. The AM path handles amplitude modulation while the FM path handles frequency modulation, allowing each path to be optimized separately. This segmentation enables wide bandwidth operation without requiring a single complex DCO to handle all frequency variations.
Solution Approach 2:
The invention changes the operating parameters of the FM path by limiting the frequency deviation range. Instead of allowing large frequency deviations that cause peak frequency issues, the system constrains the FM path to operate within a controlled deviation range, reducing DCO complexity while maintaining wide overall bandwidth through the combined AM-FM approach.
2Adaptability or versatility
If large frequency deviations are used in the DCO, then the frequency modulation range is improved, but nonlinearity problems occur and overall performance degrades
Solution Approach 1:
By separating the modulation into independent AM and FM paths, the system avoids the nonlinearity issues that arise when large frequency deviations are applied in a unified approach. Each path can be linearized independently, with the AM path handling amplitude variations and the FM path handling frequency variations within a controlled range.
Solution Approach 2:
The invention changes the frequency deviation parameter from large to controlled/small ranges in the FM path. This parameter change eliminates nonlinearity problems while maintaining adequate frequency modulation range through the combination of AM and FM paths, thereby improving overall system linearity and performance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach improves peak frequency phenomena, reduces the complexity of the phase-locked loop circuit, and maintains linearity, enhancing the overall performance of the transmitter.
Implementation Method 1
The frequency modulating path performs frequency modulation in response to the modified phase/frequency deviation signal and outputs a frequency modulated carrier signal
Data Source
AI summary
A transmitter is provided. The transmitter includes a phase/frequency deviation input, a controller and a frequency modulating path. The phase/frequency deviation input receives multiple phase/frequency deviation samples. The controller outputs a modified phase/frequency deviation signal and generates a phase/frequency deviation carry-out signal in response to the phase/frequency deviation samples and a previous time sample of the phase/frequency deviation carry-out signal. The frequency modulating path performs frequency modulation in response to the modified phase/frequency deviation signal and outputs a frequency modulated carrier signal.