Multi-Stage Non-Overlapping Clock Generation for Pipelined ADCs
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Solution Overview
Problem
Conventional non-overlapping clock generator circuits become inefficient and complex at high clock frequencies, leading to power and area issues in switched capacitor circuits, particularly in pipelined analog-to-digital converters, where a single clock generator must meet the requirements of all stages, resulting in over-design and precision synchronization challenges across stages.
Innovation Solution
A multi-stage clock generator architecture that generates multiple non-overlapping clock signals and phases, with a back end clock generator producing primary and delayed clock signals, and intermediate and first-stage generators producing phase-specific signals, ensuring mutual non-overlapping and synchronized clock signals across stages, reducing power and area requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single clock generator circuit is used to generate all clock signal variants for multiple stages, then all stages can be synchronized, but the circuit becomes over-designed, excessively complex, and requires impractical power and area
Solution Approach 1:
The clock generator is divided into multiple independent stages, where each stage generates clock signals for a specific converter stage. This segmentation reduces the complexity of each individual clock generator while maintaining synchronization through shared clock distribution networks and controlled impedance routing.
Solution Approach 2:
A single primary clock signal is distributed to multiple clock generator stages, which then generate various clock signal variants (non-inverted, inverted, delayed) for different converter stages. This multi-functionality allows the system to serve multiple purposes with a unified clock source.
2Reliability
If a single clock generator circuit is used to drive all stages, then synchronization is maintained, but power consumption and area requirements become impractical
Solution Approach 1:
The clock generation function is segmented across multiple stages, with each stage consuming power only for its specific load. This eliminates the need for a single high-power clock generator that must drive all stages, significantly reducing total power consumption while maintaining synchronization through controlled impedance routing.
Solution Approach 2:
Each clock generator stage is optimized to drive only its local converter stage load, allowing for localized power optimization. The clock signals are distributed through controlled impedance networks that maintain signal integrity without requiring excessive power from any single source.
3Manufacturing precision
If conventional non-overlapping clock generator circuits are used at high clock frequencies, then non-overlapping clock signals are generated, but an unacceptably large portion of the clock period is consumed by the generation process
Solution Approach 1:
The clock generator stages are designed to pre-charge and pre-discharge capacitive loads during dedicated time intervals before the actual clock edge transitions. This preliminary action ensures that the non-overlapping clock signals are established quickly and accurately, minimizing the time consumed by the generation process and enabling higher clock frequencies.
Solution Approach 2:
The clock generation process uses periodic charging and discharging cycles with carefully controlled durations. By optimizing the period of these internal charging/discharging cycles, the system achieves precise non-overlapping timing while minimizing the overall clock period, thereby enabling high-frequency operation.
4Use of energy by stationary object
If local per-stage clock generator circuits are used, then power and area are reduced, but synchronization across stages becomes difficult to achieve
Solution Approach 1:
The system is segmented into independent clock generator stages, each optimized for local power efficiency. Synchronization across stages is achieved through controlled impedance routing and shared reference clock signals, allowing each stage to operate independently while maintaining global synchronization.
Solution Approach 2:
Controlled impedance routing networks act as intermediaries between clock generator stages, ensuring that clock signals are transmitted with consistent timing and amplitude characteristics. This intermediary infrastructure enables synchronization across distributed stages without requiring complex communication protocols or high power consumption.
Data Source
AI summary
A multi-stage non-overlapping clock signal generator as described herein is suitable for use with a pipelined analog-to-digital converter architecture. The clock signal generator generally includes a back end clock generator, a second stage clock generator, and a first stage clock generator coupled in series. The clock signal generator may also include any number of intermediate stage clock generators coupled in series between the back end clock generator and the second stage clock generator. Example implementations of the various clock generator stages are also described herein.