Digital RF Modulator with Dual Mixer Stages for Precise Frequency Control
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Solution Overview
Problem
Existing radio-frequency signal modulators for magnetic resonance systems require costly and complex analog components for precision and multichannel operations, leading to increased expenditure and costs, especially in systems needing multiple precision mixers for sideband and carrier suppression.
Innovation Solution
A digital modulator design with multiple mixer stages and phase accumulators, utilizing a phase-amplitude transducer to generate oscillator signals with adjustable frequencies, allowing for precise radio-frequency signal generation and multichannel modulation without the need for analog components, thereby simplifying the modulation process and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If analog mixer stages are used for precision modulation, then modulation precision is improved, but device complexity and cost increase due to complicated compensation requirements and precision components
Solution Approach 1:
The patent replaces the analog mixer stage (mechanical/electrical system) with a digital modulator comprising a phase accumulator, phase-amplitude transducer, and digital mixer. This substitution eliminates the need for analog compensation circuits and precision analog components, thereby reducing device complexity while maintaining modulation precision through digital signal processing.
Solution Approach 2:
The invention changes the operating parameters from analog domain to digital domain. The phase accumulator generates phase values digitally, which are then converted to amplitude values by the phase-amplitude transducer. This parameter transformation allows precise control of modulation depth and frequency without the complexity of analog compensation, resolving the contradiction between precision and complexity.
2Measurement precision
If precision mixers are used for sideband and carrier suppression, then modulation precision is improved, but cost increases due to expensive precision components required multiple times
Solution Approach 1:
The patent replaces expensive precision analog mixers with a digital modulator architecture. The digital mixer performs sideband and carrier suppression using digital signal processing algorithms, eliminating the need for multiple costly precision analog components. This substitution maintains suppression precision while significantly reducing system cost.
Solution Approach 2:
The invention uses a single phase-amplitude transducer that can be programmatically configured to perform multiple functions (sideband suppression, carrier suppression, frequency modulation) that previously required multiple separate precision analog components. This functional copying through software configuration reduces the quantity of expensive hardware needed.
3Adaptability or versatility
If analog components are used for multichannel transmission, then channel versatility is improved, but device complexity and cost increase due to multiple precision components required
Solution Approach 1:
The patent implements a universal digital modulator architecture where a single phase accumulator and phase-amplitude transducer can generate multiple independent modulation channels through digital signal processing. Each channel can be independently configured for different frequencies, amplitudes, and modulation types, providing multichannel versatility without requiring multiple separate analog modulation circuits, thereby reducing overall device complexity.
Data Source
AI summary
A modulator for radio-frequency signals designed an entirely digital modulator has two mixer stages connected in series. The first mixer stage implements with a relatively low first sample rate a frequency mixing with a first oscillator frequency that is adjustable with high precision. The second mixer stage implements a frequency mixing with a significantly higher second sample rate and with a relatively coarsely adjustable second oscillator frequency. The downstream second mixer stage, in the case of a single mixer stage, the mixer stage, has at least two phase accumulators that are incremented with the higher second sample rate but with different incremental values. The output signal of at maximum one of the phase accumulators is evaluated at any point in time.