Dual-Amplifier Sample-and-Hold Circuit for Low-Power Linearity

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Solution Overview

Problem

Existing sample and hold circuits face high power consumption due to the need for high-bandwidth amplifiers to maintain linearity, which is undesirable.

Innovation Solution

The implementation of two separate amplifiers, where one amplifier maintains the impedance of the sampling switch constant using a boost circuit, allowing the second amplifier to be a low-bandwidth, low-power amplifier, thereby reducing power consumption while ensuring linearity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a high bandwidth amplifier is used to drive the sample and hold circuit, then linearity between captured samples and input signal strengths is improved, but power consumption increases

Engineering Contradiction:

ImprovelinearityVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent divides the amplification function into two separate amplifiers: a first amplifier that drives the boost circuit to maintain constant sampling switch impedance, and a second amplifier that drives the sample and hold circuit. This segmentation allows each amplifier to be optimized for its specific function, enabling the second amplifier to operate at lower power while maintaining linearity through the impedance control provided by the first amplifier.

Inventive Principle:

Principle #1Segmentation

2Measurement precision

If a high bandwidth amplifier is used to drive the sample and hold circuit, then signal amplification quality is improved, but device complexity increases

Engineering Contradiction:

Improvesignal amplification qualityVSAvoidamplifier bandwidth requirements

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the amplification task into two independent amplifiers with distinct functions. The first amplifier handles impedance control for the sampling switch, while the second amplifier handles signal amplification for the sample and hold circuit. This segmentation reduces the bandwidth requirement for the second amplifier, thereby reducing device complexity while maintaining signal amplification quality.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The first amplifier acts as an intermediary that controls the impedance of the sampling switch through the boost circuit. By mediating the impedance control function, the first amplifier enables the second amplifier to operate with reduced bandwidth requirements, simplifying the overall device complexity while preserving signal quality.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS7724042B2Reducing power consumption in an amplification stage driving a sample and hold circuit while maintaining linearity

Publication Date: 2010.05.25 TEXAS INSTRUMENTS INC

AI summary

An input signal to be sampled by a sample and hold circuit is amplified separately by two amplifiers. The output of the first amplifier is provided to a boost circuit to maintain the impedance of a sampling switch contained in a signal dependent boost switch substantially constant. The output of the second amplifier is sampled via the sampling switch, and the sample is stored in a storage element. The second amplifier drives a reduced load, and may be implemented as a low bandwidth, low power amplifier to reduce overall power consumption.