Closed-Loop GFSK Modulator With Pulse Compensation
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Solution Overview
Problem
Conventional GFSK modulators based on open-loop phase lock loops suffer from increased residual frequency modulation, which affects the stability of receiving systems and is not effectively controlled.
Innovation Solution
A GFSK modulator comprising a first and second compensation module for amplitude and delay compensation, combined with a closed-loop PLL module, generates compensated control signals to minimize residual frequency modulation and ensure system stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If an open-loop PLL is used in a GFSK modulator, then the device complexity is reduced, but residual frequency modulation increases and system stability deteriorates
Solution Approach 1:
The patent transitions from an open-loop PLL to a closed-loop PLL structure, introducing feedback control to continuously monitor and correct frequency deviations. The phase detector compares the VCO output with a reference signal and feeds back error signals to adjust the VCO, thereby eliminating residual frequency modulation and improving system stability while maintaining reasonable device complexity.
Solution Approach 2:
The patent introduces compensation modules that dynamically adjust amplitude and delay parameters of the GFSK pulse signal before it reaches the PLL. By changing these parameters in real-time based on detected errors, the system compensates for frequency deviations and maintains stable operation without requiring a completely complex modulator architecture.
2Device complexity
If an open-loop PLL is used in a GFSK modulator, then the device complexity is reduced, but residual frequency modulation increases
Solution Approach 1:
The closed-loop PLL provides continuous feedback control that detects and corrects frequency modulation errors. The phase detector measures the phase difference between the modulated signal and reference, generating error signals that are fed back to the VCO to precisely control the frequency modulation, thereby improving manufacturing precision without significantly increasing device complexity.
Solution Approach 2:
The patent employs compensation modules that perform preliminary amplitude and delay adjustments on the GFSK pulse signal before it enters the PLL. This preliminary action pre-corrects potential frequency deviations, reducing the burden on the PLL and enabling more precise frequency modulation control with moderate device complexity.
3Manufacturing precision
If compensation modules are added to the GFSK modulator, then residual frequency modulation is reduced, but device complexity increases
Solution Approach 1:
The patent integrates the compensation modules directly into the PLL structure, merging the amplitude and delay compensation functions with the phase detection and frequency control functions. This consolidation achieves precise frequency modulation control while minimizing the increase in device complexity by sharing common components and signal paths between the compensation modules and the PLL.
Data Source
AI summary
A GFSK modulator comprises: a first compensation module, configured to receive a GFSK pulse signal, apply a first amplitude compensation and a first delay compensation to the GFSK pulse signal, so as to generate a first compensated control signal; a second compensation module, configured to receive the GFSK pulse signal, apply a second amplitude compensation and a second delay compensation to the GFSK pulse signal, so as to generate a second compensated control signal; a closed-loop PLL module including a closed-loop PLL, configured to receive and use the first and the second compensated control signals to generate a modulated signal.