Inductive Peaking Output Driver for ISI Reduction

Solution Overview

Problem

Existing output drivers experience Inter-Symbol Interference (ISI) due to waveform distortion when driving large loads, leading to reduced timing and voltage margins, and conventional solutions like pre-emphasis drivers increase size and power consumption.

Innovation Solution

The output driver incorporates pull-up and pull-down units with inductive peaking elements, which adjust the output node voltage and perform inductive peaking operations during data signal transitions, reducing ISI by implementing inductance between nodes and using pre-emphasis control signals to optimize voltage levels and resistor values.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional pre-emphasis driver is added to overcome ISI, then the output waveform distortion is reduced, but the device size and power consumption increase

Engineering Contradiction:

Improveoutput waveform qualityVSAvoiddriver structure size

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the pre-emphasis function with the main driver by sharing the PMOS and NMOS transistors between both functions. The same pull-up and pull-down units serve both as main drivers and pre-emphasis drivers, eliminating the need for separate dedicated pre-emphasis driver circuits and reducing overall device size.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The driver circuit is designed with multi-functional transistors that can operate in different modes. The PMOS and NMOS transistors function as both main drive elements and pre-emphasis elements depending on the control signals applied, allowing a single circuit to perform multiple functions without requiring separate dedicated components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If a conventional pre-emphasis driver is added to overcome ISI, then the output waveform distortion is reduced, but the power consumption increases

Engineering Contradiction:

Improveoutput waveform qualityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent combines the pre-emphasis function with the main driver by sharing the PMOS and NMOS transistors between both functions. The same pull-up and pull-down units serve both as main drivers and pre-emphasis drivers, eliminating the need for separate dedicated pre-emphasis driver circuits and reducing overall device size.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The driver circuit is designed with multi-functional transistors that can operate in different modes. The PMOS and NMOS transistors function as both main drive elements and pre-emphasis elements depending on the control signals applied, allowing a single circuit to perform multiple functions without requiring separate dedicated components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Strength

If the rising time and falling time of output data signal are increased, then the output voltage level is improved, but the ISI occurs when the signal transitions are slower than the clock period

Engineering Contradiction:

Improveoutput voltage levelVSAvoidsignal stability in channel

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent applies preliminary action by using the pre-emphasis function to anticipate and compensate for signal degradation before it occurs. The circuit detects previous data patterns and applies compensatory voltage adjustments in advance, boosting the output signal strength proactively to counteract expected ISI effects from slow transitions.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent dynamically changes circuit parameters based on detected data patterns. When slow transitions are detected, the circuit adjusts the drive strength and voltage levels of the pull-up and pull-down units to optimize the output waveform, changing operational parameters in response to signal conditions.

Inventive Principle:

Principle #35Parameter changes

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 decreases data signal pattern-dependent skew, enhances timing and voltage margins, and reduces power consumption by eliminating the need for a separate pre-emphasis driver, resulting in a more compact and efficient output driver design.

Implementation Method 1

the first and second inductive peaking elements perform an inductive peaking operation when the input data signal transitions

Methodology Applied

Scientific EffectInductive peaking: Electromagnetic Induction

Data Source

PatentUS7463073B2Output driver

Publication Date: 2008.12.09 SAMSUNG ELECTRONICS CO LTD

AI summary

An output driver includes a pull-up unit including a pull-up element and a first inductive peaking element connected in series between a first voltage and an output node and a pull-down unit including a pull-down element and a second inductive peaking element connected in series between a second voltage and the output node. The pull-up and pull-down elements receive an input data signal and adjust a voltage level of the output node, and the first and second inductive peaking elements perform an inductive peaking operation when the input data signal transitions.