Cascade Integrator ADC Transfer Shaping for Faster Conversion
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Solution Overview
Problem
Conventional integral analog-to-digital converters (ADCs) have a slow conversion rate due to their working principle, and previous attempts to improve this by altering the reference voltage waveform are complex, difficult to expand, and result in poor linearity of the transfer characteristic.
Innovation Solution
A cascade N-stage integrator structure is used, where each integrator consists of a resistor, capacitor, operational transconductance amplifier, and switch, with the output of each integrator connected to the input of the next, resulting in a voltage change proportional to time to the power of N, improving the conversion efficiency and linearity of the ADC.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the reference voltage waveform is changed to improve conversion rate, then the conversion rate increases, but the linearity of transfer characteristic deteriorates
Solution Approach 1:
The patent divides the single integrator into multiple cascaded integrator stages. Each integrator processes the signal sequentially, with the output of one feeding into the next. This segmentation allows the system to achieve higher conversion rates through the polyphase structure while maintaining linearity through the controlled cascaded integration process, resolving the contradiction between speed and accuracy.
2Productivity
If the reference voltage waveform is altered to increase conversion rate, then the conversion rate improves, but the system complexity increases
Solution Approach 1:
The patent creates multiple copies of the integrator circuit arranged in a cascaded structure. Rather than designing a completely new complex waveform generation system, it replicates the basic integrator unit multiple times and connects them in sequence. This copying approach increases conversion rate through the polyphase structure while keeping each individual stage simple and manageable, thus improving productivity without excessive complexity increase.
3Device complexity
If conventional integrator or DAC is used to generate reference voltage, then the structure is simple, but the conversion rate is slow
Solution Approach 1:
The patent transforms the static single-integrator structure into a dynamic multi-stage cascaded system. The reference voltage is generated dynamically through the sequential operation of multiple integrator stages, each contributing to the overall conversion process. This dynamic structure enables faster conversion rates compared to the static conventional approach, while maintaining structural simplicity through the regular cascaded configuration of identical stages.
Data Source
AI summary
A system and method for regulating transfer characteristics of an integral analog-to-digital converter are provided. The system comprises a cascade N-stage integrator structure having N integrators, the input end of the first integrator is connected to a voltage, the output end of each integrator is connected to the input end of the adjacent integrator, and the output end of the Nth integrator is connected to an output node (VRAMP). Wherein, the N is positive integer greater than or equal to 2. In the cascade multistage integrator structure, the voltage of the output node (VRAMP) is in direct proportion relation with the time to the power of N. By adopting a cascade multistage integrator according to the present disclosure, it is simple to regulate transfer characteristics of the ADC, and the cascade digital signal processing is convenient, which can reduce the ADC conversion time and improve the ADC conversion rate. Compared with the existing polyline mode, the present disclosure has better linearity; and it can be easily extended to cascade multistage integrators.