Spread Spectrum Clock Control for EMI-Stable Function Blocks
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Solution Overview
Problem
In electronic devices, the varying modulation rates of spread spectrum clocks across different function blocks within a clock distribution network make it difficult to maintain stability and reduce electromagnetic interference (EMI), particularly at blocks like SD and eMMC.
Innovation Solution
An integrated circuit with a spread spectrum clock generator, clock distribution circuit, and control circuit that dynamically adjusts the frequency modulation rate of the spread spectrum clock based on the operation states of function blocks, using stored modulation rate values to minimize EMI by selecting the smaller rate between operating blocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a minimum frequency modulation rate value is selected to maintain stability of all blocks, then stability of each block is maintained, but EMI reduction at blocks requiring higher modulation rates (such as SD block) is impossible
Solution Approach 1:
The patent divides the clock distribution network into multiple independent clock distribution circuits, each serving specific function blocks. Each clock distribution circuit can independently select and apply different frequency modulation rate values suitable for its served blocks, allowing the SD block to receive a higher modulation rate (e.g., 2%) for EMI reduction while other blocks receive appropriate rates for their stability requirements.
Solution Approach 2:
The patent enables dynamic selection of frequency modulation rate values based on the operational requirements of different function blocks. The system can dynamically adjust which modulation rate is applied to each clock distribution circuit according to the active blocks and their EMI/stability requirements, rather than using a fixed minimum rate for all blocks.
2Object-generated harmful factors
If different frequency modulation rate values are used for different function blocks, then EMI can be reduced at each block, but the complexity of the clock distribution network increases
Solution Approach 1:
The clock distribution network is segmented into multiple independent clock distribution circuits, where each circuit is responsible for distributing clocks to specific function blocks. This segmentation allows each circuit to use optimized frequency modulation rate values for its served blocks without affecting other parts of the network, achieving EMI reduction while managing complexity through modular organization.
Solution Approach 2:
Each clock distribution circuit is designed to be multi-functional, capable of serving different function blocks with different modulation rate requirements. The circuits can dynamically adapt to serve various blocks (e.g., SD block, eMMC block, USB block) and apply appropriate modulation rates, reducing the need for completely separate dedicated circuits for each block type.
Data Source
AI summary
An integrated circuit according to an embodiment of the disclosure may include a plurality of function blocks, a spread spectrum clock (SSC) generator that generates a spread spectrum clock based on a frequency modulation rate value, a clock distribution circuit that distributes the generated spread spectrum clock into the plurality of function blocks, a memory that stores predetermined frequency modulation rate values respectively corresponding to the plurality of function blocks, and a control circuit, and the control circuit may be configured to generate the spread spectrum clock based on a smaller frequency modulation rate value among a first frequency modulation rate value and a second frequency modulation rate value respectively corresponding to a first function block and a second function block, which are operating, from among the plurality of function blocks. Moreover, various embodiment found through the present disclosure are possible.