Dual-Input Bootstrapped Switch for High-Linearity ADC Sampling

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Solution Overview

Problem

High-frequency analog input signals in ADC circuits face signal integrity issues due to parasitic R-L-C components, leading to distortion and limited linearity, especially in time-interleaved ADC architectures with multi-GHz sampling rates, where thermal noise and charge injection further degrade performance.

Innovation Solution

A dual-input bootstrapped switch circuit is implemented, separating signal sampling from bootstrapped driving signals, using a current-feedback operational amplifier with multiple outputs to maintain linearity and reduce switching noise, with a bootstrapper capacitor driving the sampling switch to maintain constant VGS over input ranges.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional single-input bootstrapped switch is used, then the circuit structure is simple, but signal integrity deteriorates at high frequencies due to parasitic R-L-C components causing distortion

Engineering Contradiction:

Improvesignal integrityVSAvoidcircuit structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent divides the single input signal path into two separate input paths (first input and second input). The first input receives the analog voltage signal while the second input receives a scaled version of the same signal. This segmentation allows the circuit to process signals through multiple parallel paths, reducing the impact of parasitic R-L-C components on signal integrity at high frequencies.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces an operational amplifier as an intermediary element that scales the second input signal and combines it with the first input signal. This intermediary component actively compensates for distortion caused by parasitic elements, maintaining signal integrity without requiring complete redesign of the basic bootstrapped switch structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If higher sampling rates are used to increase productivity, then data conversion speed improves, but thermal noise and charge injection increase degrading linearity

Engineering Contradiction:

Improvesampling rateVSAvoidlinearity

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent employs feedback through the operational amplifier that monitors the combined signal from both inputs and actively adjusts the scaled signal to compensate for non-linearities. This feedback mechanism allows the circuit to maintain high linearity even at multi-GHz sampling rates where thermal noise and charge injection would normally degrade performance.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent changes the signal parameters by introducing a scaled version of the input signal through the second input path. By adjusting the scaling factor and combining it with the original signal, the circuit optimizes the signal-to-noise ratio and maintains linearity at high sampling rates, effectively changing how the signal is processed rather than simply increasing speed.

Inventive Principle:

Principle #35Parameter changes

3Speed

If the bootstrapper capacitor is used to drive the switching element, then switching speed increases, but switching noise is generated affecting signal quality

Engineering Contradiction:

Improveswitching speedVSAvoidswitching noise

Core Design Contradiction:

SpeedVSObject-generated harmful factors

Solution Approach 1:

The patent extracts the switching function into a separate bootstrapped switch component driven by the bootstrapper capacitor, while the main signal path processes the combined analog signals through the operational amplifier. This separation allows the switching noise to be isolated from the signal path, maintaining high switching speed while reducing the impact of switching noise on signal quality.

Inventive Principle:

Principle #2Taking out (Extraction)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This configuration enhances signal integrity, linearity, and reduces power dissipation, improving ADC performance by minimizing thermal noise and switching noise, while allowing for higher data rates and increased sampling speeds.

Implementation Method 1

a bootstrapper capacitor configured to drive the switching element

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

a current-feedback operational amplifier with multiple outputs to maintain linearity

Methodology Applied

Scientific EffectOperational amplification:

Data Source

PatentUS11601121B2Bootstrapped switch circuit, a track-and-hold circuit, an analog-to-digital converter, a method for operating a track-and-hold circuit, a base station and a mobile device

Publication Date: 2023.03.07 INTEL CORP

AI summary

The present disclosure relates to a bootstrapped switch circuit, a track-and-hold circuit, an analog-to-digital converter, a method for operating a track-and-hold circuit, a base station, and a mobile station. The bootstrapped switch circuit comprises an output for an output signal, a first input, a switching element configured to couple the output with a signal from the first input, a bootstrapper capacitor configured to drive the switching element, and a second input coupled to the bootstrapper capacitor.