Parallel ADC Reference Ladder for Fast Low-Noise Imaging Readout
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Solution Overview
Problem
Current analog-to-digital conversion technologies face challenges in achieving high-speed conversion of multiple analog signals while minimizing energy consumption and surface area, often resulting in conflicting characteristics such as high energy consumption and increased complexity due to the need for multiple ADC circuits, which also introduce fixed pattern noise.
Innovation Solution
A device with a single circuit for generating constant and decreasing reference voltages, using a current source, resistive bridge, and voltage source, along with digitization circuits for comparing and counting these voltages to determine digital values, allowing for parallel processing without modifying the input signal and reducing the need for extensive analog processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a single ADC circuit is used for all analog signals, then the surface area and number of electronic components are reduced, but the conversion speed must be extremely high which increases energy consumption
Solution Approach 1:
The patent divides the conversion process into two independent stages: a shared analog preprocessing stage that performs initial signal conditioning and coarse conversion, and multiple parallel digital conversion stages that handle different signal groups. This segmentation allows the analog circuit to operate at lower speed while maintaining overall high conversion throughput, reducing energy consumption.
Solution Approach 2:
The patent transitions from a purely temporal dimension approach (single high-speed ADC processing signals sequentially) to a spatial dimension approach by implementing multiple parallel ADC circuits that simultaneously process different signal groups. This dimensional shift distributes the conversion load across multiple lower-speed circuits, reducing the energy consumption of each individual circuit.
2Productivity
If multiple ADC circuits are provided to increase conversion speed, then energy consumption per circuit is reduced, but the total surface area and device complexity increase
Solution Approach 1:
The patent merges the analog preprocessing functions (amplification, filtering, and coarse conversion) into a single shared circuit that serves all ADC channels. This consolidation eliminates redundant analog components across multiple ADC circuits, significantly reducing total surface area while maintaining high conversion speed through parallel digital processing stages.
Solution Approach 2:
The shared analog preprocessing circuit is designed to be universal, handling signal conditioning and initial conversion for multiple different signal groups. This multi-functional circuit replaces what would otherwise require separate dedicated circuits for each ADC channel, reducing overall device complexity and surface area.
3Productivity
If multiple ADC circuits are used for parallel conversion, then conversion speed increases, but fixed pattern noise is introduced due to operational differences between circuits
Solution Approach 1:
The patent segments the signal processing into a shared analog domain and separate digital domains. By performing initial analog preprocessing in a common circuit with consistent characteristics, the source of fixed pattern noise is eliminated. The subsequent digital processing stages operate on already-converted data, preventing noise introduction while maintaining high conversion speed.
4Measurement precision
If high gain amplifiers with multiple stages are used for precise subtraction operations, then measurement precision is improved, but device complexity and energy consumption increase
Solution Approach 1:
The patent performs preliminary signal conditioning, amplification, and coarse conversion in the analog domain before the signals are distributed to multiple digital ADC circuits. This preliminary action prepares the signals in advance, reducing the precision requirements and complexity of subsequent digital processing stages while maintaining overall measurement precision.
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 enables high-speed, low-energy, and low-surface-area analog-to-digital conversion with reduced fixed pattern noise, as it utilizes a single analog circuit for multiple signals and straightforward digital components, maintaining signal integrity and minimizing energy consumption.
Implementation Method 1
a first resistive bridge formed of resistances in series and connected to the constant current source, the voltages at the nodes of the first resistive bridge forming the reference voltages
Implementation Method 2
a voltage source capable of producing a decreasing voltage on an injection node of the first resistive bridge
Data Source
AI summary
An ADC includes a single circuit for generating reference voltages that are constant and then decreasing over time. The ADC includes a constant current source and a resistive bridge connected to the current source. A voltage source produces a decreasing voltage on a node of the bridge. The ADC also includes a contact breaker for the connection of the voltage source to the node. The ADC also includes a digitization circuit which includes a means for comparing a voltage, a means for selecting a reference voltage, a means for counting, and a means for storing on the one hand, a reference associated with the constant reference voltage which is immediately lower than or equal to the voltage for conversion, and on the other hand, the number of counted time units.