Pipeline ADC Comparator Circuit for Bandwidth Matching

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Solution Overview

Problem

The use of a comparator with a single-capacitor architecture in pipeline ADCs leads to a bandwidth mismatch when combined with a pipeline MDAC, resulting in reduced transmission rates due to a first-order sampling network and higher kickback noise.

Innovation Solution

A comparator circuit with a switch capacitor, pre-amplification, and latch circuit is designed, incorporating a resistance-adjustable device and differential static latch to adjust the sampling network to a first-order system, reducing kickback noise and matching the transmission rate with high-speed pipeline ADCs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If a comparator with single-capacitor architecture is used, then the transmission rate of the comparator is increased, but a bandwidth mismatch problem occurs between the second-order sampling network of the comparator and the first-order sampling network of the pipeline MIDAC

Engineering Contradiction:

Improvetransmission rate of comparatorVSAvoidbandwidth matching between comparator and pipeline MIDAC

Core Design Contradiction:

SpeedVSAdaptability or versatility

Solution Approach 1:

The patent introduces a resistance-adjustable device in the pre-amplification circuit that can dynamically adjust its resistance value. This allows the sampling network of the comparator to adapt its bandwidth characteristics to match the first-order sampling network of the pipeline MIDAC, resolving the bandwidth mismatch problem while maintaining high transmission rate

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the order of the sampling network from second-order to first-order by modifying the circuit architecture. Specifically, it adjusts the network order to match the pipeline MIDAC's first-order sampling network, thereby achieving bandwidth compatibility without sacrificing transmission rate

Inventive Principle:

Principle #35Parameter changes

2Productivity

If a comparator with single-capacitor architecture is used, then the conversion rate of the pipeline ADC is increased, but kickback noise is generated due to bandwidth mismatch

Engineering Contradiction:

Improveconversion rate of pipeline ADCVSAvoidkickback noise

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The resistance-adjustable device enables dynamic adaptation of the sampling network's bandwidth to match the pipeline MIDAC's first-order network. This bandwidth matching prevents the generation of kickback noise while maintaining the high conversion rate achieved by the single-capacitor architecture

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent converts the potential harmful effect of bandwidth mismatch into a beneficial adaptive feature. By making the resistance adjustable, the system can intentionally create controlled impedance matching conditions that prevent kickback noise generation while preserving the high-speed performance benefits

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS11271579B2Comparator circuit applicable to high-speed pipeline ADC

Publication Date: 2022.03.08 CETC CHIPS TECH GRP CO LTD

AI summary

The present invention provides a comparator circuit applicable to a high-speed pipeline ADC. The comparator circuit includes a switch capacitor circuit, a pre-amplification circuit, and a latch circuit. The pre-amplification circuit includes a pre-amplifier, a resistance-adjustable device, two switches. The latch circuit includes a differential static latch, a first capacitor, a second capacitor, and a third switch. The transmission rates of a sampling phase and a setup phase can be increased.