Dual-Level Clock Distribution for High-Frequency Semiconductor I/O

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Solution Overview

Problem

Existing semiconductor apparatuses face challenges in performing stable clock signaling operations at high frequencies due to the need for efficient distribution of system clock signals between complementary metal oxide semiconductor (CMOS) and current mode logic (CML) levels, which affects power consumption and noise immunity.

Innovation Solution

The semiconductor apparatus incorporates a global clock tree and local clock tree that generate and distribute clock signals at both CMOS and CML levels, allowing for flexible operation modes based on type, frequency, and voltage conditions to optimize power consumption and noise immunity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If the system clock signal is driven to CML level for high-frequency stable signaling, then noise immunity is improved, but power consumption increases

Engineering Contradiction:

Improvenoise immunityVSAvoidpower consumption

Core Design Contradiction:

Object-affected harmful factorsVSUse of energy by moving object

Solution Approach 1:

The patent implements dynamic clock signal distribution by selectively switching between CMOS and CML level clock signals based on operating conditions. The clock distribution network dynamically selects the appropriate clock signal level (CMOS or CML) for different operational modes, allowing the system to adapt power consumption and noise immunity characteristics to actual needs rather than operating at fixed CML level for all conditions.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the voltage level parameter of the clock signal from fixed CML level to variable levels (either CMOS or CML level) based on operational requirements. By controlling the clock driver to output signals at different voltage levels, the system optimizes the balance between noise immunity (favored by CML level) and power consumption (favored by CMOS level) according to actual operating conditions.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If dual clock trees (CMOS and CML) are implemented for flexible operation modes, then adaptability is improved, but device complexity increases

Engineering Contradiction:

Improveoperation mode flexibilityVSAvoidclock distribution network complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent merges the CMOS clock tree and CML clock tree into a unified clock distribution network that shares common components such as the system clock input, clock buffers, and distribution pathways. By integrating both clock level pathways within a single distributed network structure rather than maintaining completely separate systems, the patent reduces overall complexity while preserving the ability to select between CMOS and CML operating modes.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS12500589B2Semiconductor apparatus performing a plurality of clock signaling operations and semiconductor system including the same

Publication Date: 2025.12.16 SK HYNIX INC

AI summary

A semiconductor apparatus includes a clock distribution network, a data output circuit, and a data input circuit. The clock distribution network receives a system clock signal and drives the system clock signal to a CMOS level and a CML level to signal in different manners. The data output circuit outputs data based on the clock signal driven to the CMOS level. The data input circuit receives data based on the clock signal driven to the CML level.