Adaptive CTIA Charge Measurement for Compact Data Converters
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing data converters, particularly those using capacitive transimpedance amplifiers (CTIAs), face challenges due to large parasitic capacitance and resistance, requiring large chip areas and additional capacitors, which limit their versatility across different sensor array sizes, types, and dynamic ranges, and introduce noise and resolution issues.
Innovation Solution
The proposed data converter circuit includes a capacitive transimpedance amplifier (CTIA) integrated with a quantizer, digital-to-analog converter (DAC), summer, and digital filter, allowing adaptive integration and reduced feedback capacitance, enabling it to handle various array sizes, sensor types, and dynamic ranges without the need for larger capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a large feedback capacitor is used to store charge from the pixel, then the charge storage capacity is improved, but the chip area occupied increases significantly
Solution Approach 1:
The patent implements dynamic charge transfer by sequentially transferring charge from the pixel to the feedback capacitor in stages rather than requiring the feedback capacitor to hold all charge simultaneously. This allows the feedback capacitor to be smaller while still achieving the required charge storage capacity through time-multiplexed operation.
Solution Approach 2:
The patent introduces an intermediate charge transfer mechanism using switchable capacitor arrays that act as mediators between the pixel and the feedback capacitor. This allows charge to be accumulated and transferred in controlled portions, enabling the use of smaller feedback capacitors without sacrificing total charge storage capability.
2Quantity of substance
If a large feedback capacitor is used, then the charge storage capacity is improved, but the output voltage decreases requiring higher ADC resolution
Solution Approach 1:
The patent uses dynamic switching between multiple capacitor elements to effectively vary the feedback capacitance value during operation. By controlling which capacitor elements are connected, the system can adjust the effective feedback capacitance to optimize the output voltage swing and maintain adequate resolution for the ADC without requiring excessively large capacitors.
3Measurement precision
If different CTIA designs are used for different sensor array sizes and dynamic ranges, then the measurement precision is improved, but the device complexity and design cost increase
Solution Approach 1:
The patent designs a universal CTIA architecture that can accommodate different sensor array sizes and dynamic ranges through reconfigurable capacitor arrays and switchable gain stages. A single CTIA design can be programmed to handle various configurations by selectively connecting different capacitor elements, eliminating the need for multiple dedicated CTIA designs for different applications.
Solution Approach 2:
The patent implements reconfigurable feedback capacitance values that can be dynamically adjusted to match different sensor characteristics and dynamic range requirements. By changing the effective capacitance value through switching between different capacitor elements, the same hardware can be optimized for different measurement scenarios without requiring separate designs.
4Productivity
If additional capacitors are added for sample and hold circuitry, then the productivity is improved by allowing simultaneous integration and digitization, but the chip area increases
Solution Approach 1:
The patent combines the sample and hold functionality with the existing feedback capacitor structure rather than adding completely separate capacitors. By utilizing the feedback capacitor and associated switching network for both integration and holding functions, the system achieves simultaneous integration and digitization capabilities without proportionally increasing the total capacitor area.
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
This approach reduces chip area requirements, minimizes noise, and enhances flexibility by accommodating different sensor configurations while maintaining accuracy, thus reducing the need for multiple CTIA designs and lowering costs.
Implementation Method 1
A CTIA may be a charge measurement circuit used to convert charge from the sensor to a voltage value
Data Source
AI summary
Data converter circuits and methods of operating the data converter circuits are disclosed. In some embodiments, a data converter circuit includes a charge measurement circuit. In some embodiments, the charge measurement circuit is a capacitive transimpedance amplifier (CTIA). In some embodiments, the data converter circuit includes the CTIA, a quantizer, a digital-to-analog converter, a summer, and a digital filter. In some embodiments, the data converter circuit includes an analog-to-digital converter electrically coupled to the CTIA and the digital filter. In some embodiment, a method includes integrating an input signal with a CTIA, determining whether a CTIA output signal is greater than a threshold, and reducing the CTIA output signal or forgoing the reducing based on the determination of whether the CTIA output signal is greater than the threshold.