Pipelined ADC Pre-Comparison and Charge Redistribution for Fast Precision
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Solution Overview
Problem
Traditional pipelined analog-to-digital converters face limitations in achieving high-speed and high-precision conversion due to coarse quantization precision, high power consumption, and design flexibility issues, particularly in ultra-high-speed applications.
Innovation Solution
A pipelined analog-to-digital converter design incorporating input signal pre-comparison and charge redistribution, which includes a multi-stage pipelined structure unit with a first flash analog-to-digital converter and an adjusting output unit, allowing for increased quantization precision and reduced power consumption by combining highest-bit coarse quantization with sample-and-hold processes and using charge redistribution techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional pipelined ADC structure is used, then conversion speed can be improved, but quantization precision is limited by gain bandwidth and comparator quantity
Solution Approach 1:
The patent performs preliminary quantization of the input signal before it enters the main pipelined conversion process. By pre-comparing the input signal with reference voltages and determining the most significant bit in advance, the system prepares the signal for subsequent processing, thereby improving overall conversion precision without compromising speed.
Solution Approach 2:
The patent divides the quantization process into multiple independent stages: a preliminary quantization stage that processes the most significant bit, followed by the main pipelined conversion stages. This segmentation allows each stage to be optimized independently, with the preliminary stage handling coarse quantization and the pipelined stages handling fine quantization, thus resolving the precision-speed tradeoff.
2Device complexity
If time-division multiplexing is used for sampling/holding capacitors and Sub DAC capacitors, then device complexity is reduced, but conversion efficiency is severely limited
Solution Approach 1:
The patent extracts the sampling and holding function into a separate, dedicated circuit module that operates independently from the Sub DAC capacitors. By separating these functions, both the sampling/holding capacitors and the Sub DAC capacitors can operate simultaneously without mutual interference, eliminating the bottleneck caused by time-division multiplexing while maintaining reasonable device complexity.
3Measurement precision
If successive approximation pipelined structure is used, then quantization precision is improved, but conversion rate is severely limited by serial conversion process
Solution Approach 1:
The patent segments the quantization process into a parallel preliminary quantization stage and a pipelined conversion stage. The preliminary stage processes the most significant bit in parallel, while the subsequent pipelined stages process the remaining bits in sequence. This segmentation allows the system to achieve high precision without being entirely constrained by serial conversion, thereby improving the conversion rate.
Solution Approach 2:
The patent implements periodic parallel processing within the pipelined structure, where certain stages perform quantization operations in parallel during specific clock cycles. This periodic parallel action breaks the purely serial conversion process, enabling higher conversion rates while maintaining the precision benefits of successive approximation.
4Speed
If multi-channel time-interleaved structure is used, then conversion rate is increased, but power consumption increases and clock jitter limits application
Solution Approach 1:
The patent segments the conversion process into a preliminary quantization stage and a main pipelined stage, allowing the system to achieve high conversion rates through optimized single-channel processing rather than requiring multiple parallel channels. This segmentation eliminates the need for time-interleaved multi-channel structures, thereby reducing power consumption while maintaining high speed performance.
Data Source
AI summary
The present disclosure provides a pipelined analog-to-digital converter having input signal pre-comparison and charge redistribution, including: one-stage or multi-stage of pipelined structure unit, a first flash analog-to-digital converter, and an adjusting output unit. Each stage of the pipelined structure unit is used to quantify the input signal. The first flash analog-to-digital converter quantizes a residual signal output by a final pipelined structure unit, and outputs a corresponding quantized value. The adjusting output unit combines each of the quantized values according to a connection order of the multi-stage pipelined structure unit and a flash analog-to-digital conversion unit to output a complete quantization result. By using the pre-comparison and charge redistribution technologies, the number of comparators of different stages of pipelined sub ADC is reduced and the low power consumption design is achieved, signal sample-and-hold and residual signal amplification establishing are simultaneously carried out, thus improving the conversion rate.