PLL Frequency Modulation Circuit With Split Digital-Analog Control
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Solution Overview
Problem
Traditional FM transmitters with phase-locked loops face challenges in high power consumption, increased chip area due to complex high-precision digital-to-analog converter (DAC) design, and higher output noise gain in the modulation path, which complicates frequency modulation circuits.
Innovation Solution
The implementation of a frequency modulation circuit with a phase-locked loop and a voltage-controlled oscillator (VCO) that uses a combination of digital and analog modulation signals to control the frequency of the output signal, incorporating a sigma-delta modulator and switched capacitor arrays to reduce noise gain and simplify DAC design, thereby optimizing power consumption and chip area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high-precision digital-to-analog converter (DAC) is used in the frequency modulation circuit, then the frequency modulation precision is improved, but the chip area increases and manufacturing complexity increases
Solution Approach 1:
The patent segments the modulation signal processing into digital and analog domains. The input signal is divided into multiple bits, with higher-order bits processed digitally and lower-order bits processed analogously. This segmentation allows frequency modulation precision to be maintained while avoiding the need for a single high-precision DAC, thereby reducing chip area and manufacturing complexity.
Solution Approach 2:
The patent introduces an intermediary approach by using a simplified DAC that works in conjunction with analog modulation circuits. Instead of relying solely on a high-precision DAC for the entire modulation task, the system uses a combination of digital signal processing and analog modulation, where the DAC serves as an intermediary component with reduced precision requirements, thus reducing chip area while maintaining overall modulation precision.
2Measurement precision
If a high-precision digital-to-analog converter (DAC) is used in the frequency modulation circuit, then the frequency modulation precision is improved, but the power consumption increases
Solution Approach 1:
The patent segments the modulation signal processing into digital and analog domains. The input signal is divided into multiple bits, with higher-order bits processed digitally and lower-order bits processed analogously. This segmentation allows frequency modulation precision to be maintained while avoiding the need for a single high-precision DAC, thereby reducing power consumption as high-precision DACs are among the most power-hungry components in communication systems.
Solution Approach 2:
The patent introduces an intermediary approach by using a simplified DAC that works in conjunction with analog modulation circuits. Instead of relying solely on a high-precision DAC for the entire modulation task, the system uses a combination of digital signal processing and analog modulation, where the DAC serves as an intermediary component with reduced precision requirements, thus reducing power consumption while maintaining overall modulation precision.
3Measurement precision
If a complex high-precision DAC design is used, then the frequency modulation precision is improved, but the circuit complexity increases
Solution Approach 1:
The patent segments the modulation signal processing into digital and analog domains. The input signal is divided into multiple bits, with higher-order bits processed digitally and lower-order bits processed analogously. This segmentation allows frequency modulation precision to be maintained while avoiding the need for a single high-precision DAC, thereby reducing circuit complexity as high-precision DACs are among the most complex components in communication systems.
Solution Approach 2:
The patent introduces an intermediary approach by using a simplified DAC that works in conjunction with analog modulation circuits. Instead of relying solely on a high-precision DAC for the entire modulation task, the system uses a combination of digital signal processing and analog modulation, where the DAC serves as an intermediary component with reduced precision requirements, thus reducing circuit complexity while maintaining overall modulation precision.
Data Source
AI summary
A frequency modulation circuit can include: a modulation circuit configured to generate a digital modulation signal and an analog modulation signal according to an input signal of the frequency modulation circuit; and a phase-locked loop having a voltage-controlled oscillator configured to receive a reference frequency, and to modulate a frequency of an output signal of the voltage-controlled oscillator according to the analog modulation signal and the digital modulation signal.