Dual Integrator AFE Circuit for High Current, Low Noise Digitization
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Solution Overview
Problem
The existing analog front-end (AFE) systems in computed tomography applications face challenges with high power consumption, area usage, and noise production due to support circuitry, which limits performance and increases costs, while also conflicting requirements for low noise and high current signal support.
Innovation Solution
A dual integrator circuit architecture that includes a generating circuit, integrators, a comparator, and switching circuits to manage voltage signals and convert them into digitized charge values efficiently, minimizing power consumption and noise by using a continuous time sigma delta modulator with low capacitance and optimizing switching operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a high capacitance value is used in the integrator circuit, then the maximum current signal support is improved, but the noise increases
Solution Approach 1:
The patent divides the integration process into multiple segments by using a dual integrator architecture with separate integrators for different signal ranges. This allows each integrator to be optimized for its specific range, enabling high current signal support in one integrator while maintaining low noise in the other, thus resolving the contradiction between current support capability and noise generation.
Solution Approach 2:
The patent implements dynamic switching between integrators based on the input signal level. A detector circuit dynamically determines which integrator to activate, allowing the system to adapt to varying current signal levels. This dynamic operation enables the system to use high-capacitance integrators only when high current signals are present, while using low-capacitance integrators for normal operation to minimize noise.
2Adaptability or versatility
If support circuitry is added to the AFE, then the functionality is improved, but the power consumption increases
Solution Approach 1:
The patent combines multiple functions into the integrator circuit itself. The integrators perform both signal integration and act as part of the digitization process by generating voltage signals that are directly fed to the analog-to-digital converter. This merging eliminates the need for separate support circuitry, maintaining enhanced functionality while reducing power consumption.
Solution Approach 2:
The dual integrator circuit serves multiple purposes: it integrates current signals, conditions voltage outputs for different signal ranges, and interfaces with the ADC. This multi-functionality allows the circuit to replace what would traditionally require separate support circuits, thereby improving functionality without proportionally increasing power consumption.
3Adaptability or versatility
If support circuitry is added to the AFE, then the functionality is improved, but the area occupied increases
Solution Approach 1:
The patent merges the integration and digitization support functions into a single integrated circuit block. The dual integrator architecture with shared switching and control circuitry provides enhanced functionality while occupying less area than separate discrete circuits would require. The compact integration is achieved by sharing common elements such as the switching network and control logic between both integrators.
4Adaptability or versatility
If support circuitry is added to the AFE, then the functionality is improved, but the cost increases
Solution Approach 1:
The dual integrator circuit is designed as a universal building block that can handle multiple signal types and ranges within a single integrated circuit. This multi-functionality reduces the need for multiple specialized circuits, thereby simplifying manufacturing and reducing costs. The circuit can be implemented using standard CMOS process technology, further reducing manufacturing costs while maintaining enhanced functionality.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces power consumption and noise while supporting high current signals, achieving efficient digitization of X-ray beam measurements with improved performance and cost-effectiveness.
Implementation Method 1
The generating circuit, for example a photo detector 105, generates a current signal in response to the X-ray beam
Implementation Method 2
The integrator circuit 110A generates an output voltage at a node 120A. The output voltage can be realized using a capacitor 125A
Data Source
AI summary
A circuit includes a generating circuit that generates a current signal in response to an input signal, a first one of a plurality of integrators that generates a voltage signal from the current signal, a comparator that is responsive to the voltage signal to compare the voltage signal with a predefined voltage, a switching circuit that reconfigures a first capacitor and a second capacitor connected to the first one of the plurality of integrators to discharge the first capacitor and to enable the second capacitor to generate the voltage signal in response to the current signal, and an analog-to-digital converter to generate an output when a predefined time interval has elapsed. The output is obtained by adding a first charge value corresponding to a count of number of times the voltage signal reaches the predefined voltage in the predefined time interval and a second charge value from the analog-to-digital converter.