Digital RF Signal Generation via Delta-Sigma Modulation
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Solution Overview
Problem
Conventional wireless transmitters require complex high-speed digital-to-analog converters for encoding digital signals into RF signals, which is inefficient and complex due to the involved frequencies and data amounts.
Innovation Solution
The digital generation of RF signals is achieved by up-converting digital signals to a high-speed clock phase-synchronized with the RF carrier, using a band-pass delta-sigma modulator to produce a bit stream, thereby eliminating the need for high-resolution DAC converters and enabling CMOS integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-speed digital-to-analog converters with high resolution are used for encoding digital signals into RF signals, then signal transmission fidelity is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent replaces the conventional mechanical/analog DAC converter system with a digital signal processing system that performs up-conversion entirely in the digital domain. The digital up-converter takes baseband digital signals and converts them to RF digital signals synchronized with the carrier clock, eliminating the need for high-speed high-resolution DAC hardware while maintaining signal fidelity through digital processing.
Solution Approach 2:
The patent changes the operating parameters by using digital domain processing at high clock rates (e.g., 40.96 MHz) instead of analog domain processing at RF frequencies. The digital up-converter operates at a multiple of the carrier frequency, allowing the system to achieve RF signal generation through digital means rather than requiring complex analog DAC converters.
2Reliability
If conventional analog circuitry is used for signal encoding and up-conversion, then RF signal generation is achieved, but transmitter architecture complexity increases
Solution Approach 1:
The patent substitutes the traditional analog transmitter architecture with a digital architecture where signal processing, up-conversion, and modulation are performed in the digital domain. The digital up-converter and band-pass delta-sigma modulator replace multiple analog components (DACs, mixers, VCOs) with integrated digital circuitry, simplifying the overall transmitter architecture while maintaining RF signal generation capability.
Solution Approach 2:
The patent merges multiple functions into the digital up-converter and band-pass delta-sigma modulator block. These functions include digital up-conversion, frequency multiplication, phase synchronization with the carrier, and delta-sigma modulation, all integrated into a single digital processing stage that replaces multiple separate analog components.
3Measurement precision
If high-resolution DAC converters are used to convert baseband signals to RF signals, then signal quality is improved, but power consumption and integration difficulty increase
Solution Approach 1:
The patent replaces power-intensive high-resolution DAC converters with low-power digital signal processing. The digital up-converter and band-pass delta-sigma modulator perform signal conversion and modulation through digital logic operations that consume significantly less power than high-speed high-resolution analog DAC converters, while maintaining signal quality through digital processing precision.
Data Source
AI summary
The invention is directed to digital generation of RF signals. In the digital domain, digital RF signals are converted to the digital signals clocked at a high speed clock that is phase-synchronized with the RF carrier. A band-pass delta-sigma modulator produces a bit stream from the converted digital signals.