CT Pipelined VCO ADC With Phase Interpolation for Wider Bandwidth
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing analog-to-digital converters (ADCs), particularly voltage-controlled-oscillator (VCO) based continuous-time (CT) pipelined ADCs, face limitations in bandwidth and performance due to inherent non-linearity and noise, which restrict their application in high-speed and wide-bandwidth applications.
Innovation Solution
The implementation of a VCO-based CT pipelined ADC with a CT residue generation front end and a CT VCO ADC back end, where the VCO ADC back end includes phase interpolation to enhance bandwidth, and a digital signal reconstruction filter is used to combine digital signals and generate a final digital output, thereby addressing the limitations of VCO ADCs and CT pipelined ADCs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a VCO-based continuous-time pipelined ADC is used, then power consumption and silicon area are reduced, but bandwidth and performance are limited due to inherent non-linearity and noise
Solution Approach 1:
The ADC is divided into multiple pipelined stages, each handling a portion of the conversion process. This segmentation allows the system to achieve high performance through cumulative effect while keeping each individual stage simple and low-power, resolving the contradiction between power consumption and performance.
Solution Approach 2:
Feedback mechanisms are implemented to correct the inherent non-linearity and noise of VCO-based conversion. By continuously monitoring and adjusting the output, the system maintains high performance without requiring complex high-power circuitry, thus resolving the contradiction between power consumption and reliability.
2Device complexity
If a VCO-based continuous-time pipelined ADC is used, then circuit design is simplified, but bandwidth is limited due to inherent non-linearity and noise
Solution Approach 1:
Phase interpolation techniques are employed to extend the bandwidth by utilizing multiple VCO phases simultaneously. This dimensional approach allows the simple VCO-based circuit to achieve wide bandwidth by processing multiple signal dimensions in parallel, resolving the contradiction between circuit simplicity and speed.
3Speed
If phase interpolation is added to enhance bandwidth, then bandwidth and performance are improved, but device complexity increases
Solution Approach 1:
Multiple VCO phases are merged into a unified processing architecture where the phase interpolation is integrated with the pipelined stages. This combining approach achieves wide bandwidth without proportionally increasing complexity, as the same circuit structures are reused across different phases.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
VCO ADCs consume relatively little power and require less area than other ADC architectures. However, when a VCO ADC is implemented by itself, the VCO ADC can have limited bandwidth and performance. To address these issues, the VCO ADC is implemented as a back end stage in a VCO-based continuous-time (CT) pipelined ADC, where the VCO-based CT pipelined ADC has a CT residue generation front end. Optionally, the VCO ADC back end has phase interpolation to improve its bandwidth. The pipelined architecture dramatically improves the performance of the VCO ADC back end, and the overall VCO-based CT pipelined ADC is simpler than a traditional continuous-time pipelined ADC.