Semiconductor Clock Control for EMI Noise Suppression
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Solution Overview
Problem
NAND-type flash memory devices experience noise degradation and reliability issues due to electro-magnetic interference (EMI) caused by the overlap of external and internal clock signals during continuous reading operations, leading to potential misoperations and performance degradation.
Innovation Solution
A semiconductor device with a clock control part that detects the overlap period between external and internal clock signals and adjusts the internal clock signal's frequency or phase to prevent noise accumulation, using detection circuits to synchronize the clock generation with the external clock signal, thereby reducing EMI noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If continuous reading operation is performed using external clock signal, then reading speed is improved, but EMI noise is generated due to overlap with internal clock signal
Solution Approach 1:
The detection circuit detects the overlap period between external and internal clock signals in advance, and the control circuit pre-adjusts the internal clock signal timing to avoid EMI noise generation during continuous reading operations
Solution Approach 2:
The control circuit adjusts the phase or frequency of the internal clock signal based on the detected overlap period, changing the timing parameter of the internal clock to eliminate overlap with the external clock signal during continuous reading
2Object-affected harmful factors
If internal clock signal timing is adjusted to avoid overlap, then EMI noise is suppressed, but clock synchronization complexity increases
Solution Approach 1:
The detection circuit continuously monitors the overlap period between clock signals and provides feedback to the control circuit, which automatically adjusts the internal clock timing based on this feedback to maintain optimal synchronization without manual intervention
3Reliability
If detection circuit is added to monitor clock overlap, then EMI noise can be prevented, but device complexity increases
Solution Approach 1:
The detection circuit and control circuit are integrated into the existing clock generation and control infrastructure of the semiconductor device, sharing common components and signal paths to minimize additional complexity while achieving EMI noise suppression
Data Source
AI summary
A semiconductor device capable of suppressing generation of noise caused by EMI is provided. The flash memory includes a memory cell array, a clock generator (200), a readout part, an input/output circuit, an overlap detecting part (330) and a clock control part. The clock generator generates an internal clock signal. The readout part reads data from a selected memory cell of the memory cell array using the internal clock signal. The input/output circuit outputs the read data using an external clock signal supplied from outside. The overlap detecting unit detects a period during which a rising edge of the internal clock signal overlaps a rising edge of external clock signal. The clock control part controls a timing of the internal clock signal in response to the detected overlap period.