Sample and Hold Circuit Switching Noise Offset

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Solution Overview

Problem

Sample and hold circuits in display devices introduce switching noise signals during the sampling and holding of pixel information, leading to errors in pixel detection.

Innovation Solution

A sample and hold circuit configuration that includes a main sample and hold circuit for pixel information and a dummy sample and hold circuit for a reference voltage, both synchronized to offset switching noise signals, with a common coupling unit to couple the capacitors and charge sharing units, and an amplifier to differentially amplify the signals and eliminate noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If switching operations are performed in the sample and hold circuit to sample and hold pixel information, then the pixel information can be processed, but switching noise signals are introduced into the circuit

Engineering Contradiction:

Improvesignal processing capabilityVSAvoidswitching noise signal

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent creates a dummy sample and hold circuit that is an exact copy of the main sample and hold circuit structure. The dummy circuit samples a reference voltage instead of pixel information, generating a noise signal that mirrors the switching noise of the main circuit. This copied noise signal is then used to cancel the harmful noise in the main circuit output.

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The dummy sample and hold circuit acts as an intermediary that generates a noise compensation signal. This intermediary circuit allows the switching operations to proceed in the main circuit while providing a separate noise signal that can be subtracted from the main output, effectively mediating between the need for switching operations and the harmful noise they produce.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-generated harmful factors

If a dummy sample and hold circuit is added to offset switching noise, then noise elimination is achieved, but device complexity increases

Engineering Contradiction:

Improveswitching noise signalVSAvoidcircuit structure

Core Design Contradiction:

Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The patent merges the main sample and hold circuit and the dummy sample and hold circuit through a common coupling unit that shares capacitors and charge sharing units. This merging approach allows the dummy circuit to generate noise compensation signals while sharing physical components with the main circuit, thereby reducing the overall complexity increase that would result from completely separate circuits.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The dummy sample and hold circuit is designed with the same structural components as the main circuit, allowing it to serve multiple functions: generating noise signals for cancellation while maintaining architectural consistency with the main circuit. This universality in design reduces the complexity burden by reusing proven circuit patterns rather than creating entirely new noise cancellation mechanisms.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS9412308B2Sample and hold circuit and source driver including the same

Publication Date: 2016.08.09 SILICON WORKS CO LTD

AI summary

A sample and hold circuit may include: a main sample and hold circuit configured to sample and hold pixel information of an organic light emitting diode (OLED) cell, and output a first output signal; and a dummy sample and hold circuit configured to sample and hold a reference voltage in synchronization with the main sample and hold circuit, and output a second output signal for offsetting a switching noise signal contained in the first output signal.