RF Signal Synthesizer Using One DCO Across Wide Frequency Bands
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Solution Overview
Problem
Modern RF transmitters require multiple controlled oscillators (DCOs) to support various frequency bands, leading to increased engineering time, chip area, and power consumption due to the limited frequency range of a single DCO and the need for additional Digital to Analog Converters (DACs) and upsampling filters.
Innovation Solution
A radio frequency signal synthesizer circuit that utilizes a single DCO and DAC to generate RF signals across a wide frequency range by operating in multiple modes, including polar modulation and direct digital synthesis, allowing the same hardware to support both high and low frequency ranges without additional oscillators and processing circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple DCOs are used to support various frequency bands, then frequency coverage is improved, but chip area and device complexity increase
Solution Approach 1:
The patent implements a single DCO that can operate in multiple modes (polar modulation mode and direct digital synthesis mode) to cover both low and high frequency bands. The same hardware infrastructure (DCO, DAC, upsampling filter chain) is reused across different frequency ranges by switching operation modes, eliminating the need for separate DCO instances for each frequency band.
2Adaptability or versatility
If multiple DCOs are used to support various frequency bands, then frequency coverage is improved, but engineering time and device complexity increase
Solution Approach 1:
The system uses a universal transmit chain architecture where a single DCO, DAC, and upsampling filter chain can serve multiple frequency bands by switching between polar modulation mode (for high frequencies) and direct digital synthesis mode (for low frequencies). This reduces the number of separate transmit chains from multiple (one per band) to just one, significantly simplifying design, layout, testing, and verification.
3Adaptability or versatility
If multiple DCOs are used to support various frequency bands, then frequency coverage is improved, but power consumption increases
Solution Approach 1:
The patent merges the functionality of multiple separate DCOs and their associated transmit chains into a single integrated system. By combining polar modulation and direct digital synthesis approaches in one unified architecture, the system eliminates redundant components and reduces overall power consumption while maintaining comprehensive frequency band coverage.
Data Source
AI summary
A radio frequency signal synthesizer circuit includes a digital to analog converter configured to generate an analog output signal for each clock cycle of a clock signal to provide the radio frequency signal and a controlled oscillator to generate the clock signal. The controlled oscillator is configured to vary a cycle time of the clock signal for a radio frequency signal in a first frequency range in a first operation mode or to maintain a constant cycle time for a radio frequency signal in a second frequency range in a second operation mode, the second frequency range being different than the first frequency range.