EMI Cancellation Circuit for Semiconductor Data Line Shielding
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Solution Overview
Problem
Highly integrated semiconductor integrated circuits and memory devices experience electromagnetic interference (EMI) due to generated electromagnetic waves, affecting their operation and requiring effective shielding methods that do not compromise signal timing or increase circuit area.
Innovation Solution
An EMI shielding circuit that compares the number of high-level and low-level data signals across multiple data lines to generate a driving control signal, which is used to produce an EMI cancellation signal, effectively canceling electromagnetic interference by adjusting the output level of the EMI cancellation signal based on the data comparison.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If spread spectrum clocking (SSC) is used for EMI shielding, then electromagnetic interference is reduced, but the effective timing period of the signal is decreased
Solution Approach 1:
The patent extracts only the necessary EMI shielding function from the data transmission system by adding a separate EMI cancellation signal generation unit. This unit independently monitors data levels and generates cancellation signals without modifying the original data signals, thereby shielding EMI while preserving the effective timing period of data signals.
Solution Approach 2:
The patent introduces an intermediary EMI cancellation signal that acts as a mediator between the data transmission system and the EMI problem. This cancellation signal is generated based on data level comparison and is used to neutralize EMI effects without directly altering the timing characteristics of the original data signals.
2Object-affected harmful factors
If differential signaling is used for EMI shielding, then electromagnetic interference is reduced, but the circuit area is increased
Solution Approach 1:
The patent makes the data lines serve multiple functions: they simultaneously transmit data signals and provide information for EMI cancellation signal generation through level comparison. This multi-functionality eliminates the need for separate differential signaling pairs, achieving EMI shielding without increasing circuit area.
Solution Approach 2:
The patent enables the data transmission system to serve itself by using the data lines to generate the EMI cancellation signals. The level comparison unit monitors the data lines and generates cancellation signals based on the data patterns, allowing the system to shield its own EMI without requiring additional dedicated shielding circuits.
Data Source
AI summary
An electromagnetic interference (EMI) shielding circuit and a semiconductor integrated circuit including the same are provided. The EMI shielding circuit includes a data level comparison unit, a control signal generation unit, and a driver for EMI cancellation. The data level comparison unit generates a data comparison signal by comparing a number of high-level data transmitted through a plurality of data lines and a number of low-level data transmitted through the plurality of data lines. The control signal generation unit generates a driving control signal in response to the data comparison signal. The driver for EMI cancellation outputs an EMI cancellation signal in response to the driving control signal.