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 ADCs with multi-GHz sampling rates, where thermal noise and charge injection further degrade performance.
Innovation Solution
A dual-input bootstrapped switch circuit is employed, separating signal sampling from bootstrapped driving signals, using a current-feedback operational amplifier with multiple outputs to maintain linearity and reduce switching noise, thereby enhancing signal integrity and ADC performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a standard bootstrapped switch circuit is used in ADC, then the circuit can operate at high frequencies, but signal integrity deteriorates due to parasitic R-L-C components causing distortion
Solution Approach 1:
The patent segments the single bootstrapped switch circuit into two separate switch circuits: a first bootstrapped switch for sampling the analog input signal and a second bootstrapped switch for the current feedback signal. This segmentation isolates the signal sampling path from the feedback path, reducing mutual interference and parasitic effects that degrade signal integrity at high frequencies.
Solution Approach 2:
The patent introduces an intermediary current feedback path that mediates between the analog input signal and the switching elements. By using a current feedback signal generated from the analog input signal (rather than direct voltage feedback), the circuit reduces the impact of parasitic R-L-C components and improves signal integrity during high-frequency operation.
2Measurement precision
If bootstrapped switching is used to maintain linearity, then switching noise is reduced, but thermal noise and charge injection still degrade performance in time-interleaved ADCs
Solution Approach 1:
The patent separates the sampling function and feedback function into distinct switch circuits, allowing independent optimization of each path. This segmentation enables better control over noise and charge injection effects in each individual switch while maintaining overall linearity through the current feedback mechanism.
Solution Approach 2:
The patent implements a current feedback mechanism where a feedback current is generated based on the analog input signal and applied to the switching elements. This feedback actively compensates for thermal noise and charge injection effects, maintaining linearity even during high-speed switching operations in time-interleaved ADC architectures.
3Productivity
If multi-GHz sampling rates are implemented in time-interleaved ADCs, then data rate increases, but parasitic elements cause distortion and limited linearity
Solution Approach 1:
The patent divides the ADC front-end into multiple independent bootstrapped switch circuits, each handling specific signal paths. This segmentation allows each circuit to be optimized for high-frequency operation with reduced parasitic effects, enabling multi-GHz sampling rates while maintaining linearity through the distributed architecture.
Solution Approach 2:
The patent uses current feedback signals as an intermediary mechanism to maintain linearity at multi-GHz sampling rates. The current feedback path compensates for distortion caused by parasitic elements in the high-speed switching circuits, enabling high data rates without sacrificing linearity performance.
Data Source
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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.