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Write Trickling to Extend the Lifetime of the Bidirectional Data Bus Architecture for Memory Systems

IP.com Disclosure Number: IPCOM000127758D
Publication Date: 2005-Sep-13
Document File: 2 page(s) / 302K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method that converts idle periods on the command/address bus into write data transfers. Benefits include reducing the number and impact of turnarounds for writes on the data bus.

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Write Trickling to Extend the Lifetime of the Bidirectional Data Bus Architecture for Memory Systems

Disclosed is a method that converts idle periods on the command/address bus into write data transfers. Benefits include reducing the number and impact of turnarounds for writes on the
data bus.

Background

A bidirectional interface is very pin-efficient when connecting to memory devices (e.g. DRAMs); however, there is a loss of bandwidth during the idle periods required to turn the interconnect around. Such turnarounds are required between writes and reads when the interconnect transmitter and receiver exchange roles. In addition, as the data rate on bi-directional interconnects scales upward, the turnaround time will change slowly, being more a function of the propagation latency of the channel than of the speed of the logic on either end of the interconnect. Therefore, the turnarounds cause a larger and larger proportion of lost bandwidth as the data rate scales upward. Eventually, the turnaround overhead dominates as the data rate scales, and at some point it is better to use unidirectional interfaces.

General Description

The disclosed method uses a point-to-point command/address channel to transfer write data to the DRAMs (see Figure 1). The disclosed method sends write data when the command/address channel is otherwise idle. This write data has only a portion of the total bandwidth that is available on the data bus, and no turnaround is required. The disclosed method cont...