Data Output Circuit Pre-Emphasis for Stable Voltage Swing

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Solution Overview

Problem

Conventional data output circuits in semiconductor devices lack a pre-emphasis operation, leading to irregular voltage swing amplitudes based on output data patterns, which degrades jitter characteristics due to inter-symbol interference (ISI) effects.

Innovation Solution

A data output circuit is designed with a main driving unit for serializing and driving data and an auxiliary driving unit that performs pre-emphasis by inverting and driving the data output pad during periods of different logic levels, with the pre-emphasis operation period automatically adjusted based on the data output period synchronized with a clock signal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a pre-emphasis operation is implemented to maintain consistent voltage swing amplitude, then jitter characteristics are improved, but device complexity increases

Engineering Contradiction:

Improvejitter characteristicsVSAvoidcircuit structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The data output circuit is divided into two independent driving units: a main driving unit for normal data output and an auxiliary driving unit for pre-emphasis operation. This segmentation allows each unit to perform its specific function efficiently without interfering with the other, resolving the contradiction by adding functionality through structural division rather than complex integration

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The auxiliary driving unit performs pre-emphasis operation in advance by detecting transitions in output data and applying compensatory voltage swings before the main data transition occurs. This preliminary action counteracts the anticipated ISI effects and maintains consistent voltage swing amplitude, improving jitter characteristics without requiring complex real-time adjustment mechanisms

Inventive Principle:

Principle #10Preliminary action

2Reliability

If pre-emphasis operation is applied to all data patterns, then voltage swing consistency is improved, but power consumption increases

Engineering Contradiction:

Improvevoltage swing consistencyVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The auxiliary driving unit is configured to perform pre-emphasis operation only for specific data patterns where transitions occur between different logic levels, rather than applying the operation uniformly to all data patterns. This localized application of pre-emphasis maintains voltage swing consistency where needed while avoiding unnecessary power consumption for patterns that do not require compensation

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The circuit applies pre-emphasis operation partially, only during periods when the output data exhibits transitions that would cause ISI effects. By detecting specific pattern conditions and applying compensation only when necessary, the circuit achieves voltage swing consistency without the excessive power consumption that would result from continuous pre-emphasis operation

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS8604830B2Semiconductor device

Publication Date: 2013.12.10 SK HYNIX INC

AI summary

A semiconductor device includes a main driving unit configured to serialize first and second data applied in parallel and output the serialized data to a data output pad, and an auxiliary driving unit configured to drive the data output pad in a period when the first and second data have different logic levels.