MRI RF Receiver Dynamic Range Extension With Single-Bit Sigma-Delta ADC
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The dynamic range of MRI signals exceeds the capabilities of commercially available ADCs, leading to challenges in extending the dynamic range without increasing complexity and power consumption.
Innovation Solution
A radio frequency (RF) receiver system utilizing a single-bit sigma delta ADC with a variable output strength feedback DAC, coupled with an automatic gain control circuit and digital down converters, to extend the dynamic range while minimizing power consumption and design complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a multi-bit feedback DAC is used to extend dynamic range, then the dynamic range is improved, but the device complexity and power consumption increase
Solution Approach 1:
The patent segments the feedback DAC into multiple smaller DACs (e.g., two 1.5-bit DACs instead of one 3-bit DAC). Each segment operates at reduced complexity while collectively providing the required dynamic range extension. This segmentation reduces the complexity of individual DAC units and simplifies the overall ADC structure.
Solution Approach 2:
The patent employs dynamic switching between different feedback DAC configurations and gain settings. The system adapts the feedback path dynamically based on signal conditions, allowing the ADC to optimize between linear operation and dynamic range extension modes, thereby managing complexity adaptively rather than statically.
2Measurement precision
If a multi-bit feedback DAC is used to extend dynamic range, then the dynamic range is improved, but the power consumption increases
Solution Approach 1:
By dividing the feedback DAC into multiple smaller segments, each operating at lower power, the total power consumption is reduced compared to a single high-resolution DAC. The segmented architecture allows more efficient power distribution and reduces the power burden on any single component.
Solution Approach 2:
The patent changes the operational parameters of the feedback DAC by using lower-resolution multiple DACs instead of a single high-resolution DAC. This parameter change (from high-resolution single unit to low-resolution multiple units) reduces power consumption while achieving the same dynamic range extension through architectural innovation.
3Measurement precision
If the loop filter order is increased to extend dynamic range, then the dynamic range is improved, but the power consumption and chip area increase
Solution Approach 1:
The patent applies segmentation to the loop filter structure, dividing high-order filtering functions into multiple lower-order filter stages. This segmentation reduces the complexity of any single filter stage while collectively providing the required filtering performance and dynamic range extension.
4Measurement precision
If a multi-bit feedback DAC is used, then the dynamic range is improved, but the linearity requirements become more stringent
Solution Approach 1:
By segmenting the feedback DAC into multiple lower-resolution units, the linearity requirement for each individual DAC is relaxed. Each small DAC (e.g., 1.5-bit) has simpler linearity requirements compared to a single high-resolution DAC, making the system more tolerant of manufacturing variations and easier to implement with standard CMOS processes.
Data Source
AI summary
For a radio frequency (RF) receiver system (1) for providing magnetic resonance (MR) information from an examination space of a MR imaging system, a solution for increasing the dynamic range of the radio frequency (RF) receiver system (1) for a better imaging performance shall be created. A sigma delta ADC of the RF receiver system operates in single-bit mode with an automatic gain control (AGC) circuit used to control the DAC feedback strength thereby extending the dynamic range of the receiver to match the MRI signal. The present invention also refers to a magnetic resonance (MR) imaging system, a method A method for extending the dynamic range of a radio frequency (RF) receiver system, a software package for a magnetic resonance (MR) imaging system, a software package for upgrading a magnetic resonance (MR) imaging system and a computer program product.