Memory Clock Mode Configuration for Serial Flash Scaling
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Solution Overview
Problem
The existing parallel configuration of Flash memory systems faces performance limitations due to signal integrity issues like crosstalk, signal skew, and simultaneous switching noise, leading to increased power consumption and clock performance problems, which restrict the number of memory devices that can be connected effectively.
Innovation Solution
A serially connected memory system with a ring topology configuration, where memory devices are connected serially with each other and the memory controller, allowing for the use of either parallel or source synchronous clock signals, and employing a configurable input circuit and clock switch circuit to manage clock and data signals efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If parallel configuration of Flash memory devices is used, then storage capacity is increased, but signal integrity deteriorates due to crosstalk, signal skew, and simultaneous switching noise
Solution Approach 1:
The parallel bus interface is segmented into multiple independent serial lanes, with each lane carrying data between the memory controller and individual memory devices. This segmentation eliminates the crosstalk and simultaneous switching noise inherent in shared parallel buses, while maintaining the ability to access multiple devices simultaneously through time-multiplexed serial communication.
Solution Approach 2:
A serial interface protocol acts as an intermediary between the memory controller and memory devices, translating high-capacity parallel data transfers into sequential serial bit streams. This intermediary layer enables reliable point-to-point communication for each device while supporting aggregate storage capacities equivalent to parallel configurations through coordinated multi-device access.
2Quantity of substance
If more memory devices are connected in parallel, then storage capacity increases, but power consumption increases due to extensive clock distribution
Solution Approach 1:
The clock signal is extracted from the parallel interface architecture and replaced with asynchronous serial communication protocols. Each memory device operates independently without requiring synchronized clock distribution, eliminating the power-intensive clock tree that scales poorly with the number of devices. Data transfer is achieved through self-timed serial bit streams rather than clocked parallel buses.
Solution Approach 2:
Serial data transmission uses periodic bit-stream communication with configurable baud rates, allowing flexible data transfer without continuous clock signaling. The periodic nature of serial communication enables efficient power management by allowing devices to enter low-power states between transmission events, unlike parallel interfaces that require continuous clock distribution to maintain synchronization.
3Stability of the object's composition
If parallel clock distribution is used, then synchronous operation is achieved, but clock performance deteriorates with increased number of devices
Solution Approach 1:
Instead of using a master clock distributed to all devices to enforce synchronous operation, the invention inverts the approach by using asynchronous serial communication where each device operates independently. Synchronization is achieved through protocol-level handshaking and timing mechanisms in the serial interface rather than hardware clock distribution, eliminating clock skew and performance degradation.
Solution Approach 2:
The interface protocol parameters are changed from synchronous clocked parallel communication to asynchronous serial communication with configurable baud rates and timing characteristics. This parameter change allows each memory device to operate at optimal speeds independent of the number of devices in the system, maintaining reliable operation without the clock performance limitations that plague parallel architectures as device count increases.
Data Source
AI summary
A clock mode configuration circuit for a memory device is described. A memory system includes any number of memory devices serially connected to each other, where each memory device receives a clock signal. The clock signal can be provided either in parallel to all the memory devices or serially from memory device to memory device through a common clock input. The clock mode configuration circuit in each memory device is set to a parallel mode for receiving the parallel clock signal, and to a serial mode for receiving a source synchronous clock signal from a prior memory device. Depending on the set operating mode, the data input circuits will be configured for the corresponding data signal format, and the corresponding clock input circuits will be either enabled or disabled. The parallel mode and the serial mode is set by sensing a voltage level of a reference voltage provided to each memory device.