DDR SDRAM Controller Design Of PXI Oscilloscopes

The performance of memory is important in many digital systems, it mostly determines the system performance. The DDR SDRAM characterized by large memory capacity, high access speed, good stability, mature technology and high cost-effective, and it has been widely used in many storage systems.In this paper, the DDR SDRAM controller is mainly used in the PXI digital virtual oscilloscope, and it requests high speed data access, which needs to achieve 2Gbyte/s.Although the DDR SDRAM has High-speed access rate, the timing and control operation are very complex, so it needs a higher request to the design of the controller. The design of traditional DDR SDRAM controller is mostly based on MCU and DSP, but it is difficult to achieve high-speed storage in the complex digital systems for their own limited resources which have been integrated inside. And for that reason, this paper presents a new controller design; it controls the four BANK of DDR SDRAM circularly with FPGA at the same time, and ensures that there will be one BANK at least in reading or writing process. Then do the same operation to four DDR SDRAM at the same time, and eventually we will reach the request of rate about 2Gbyte/s.The paper has done the following work. Firstly, it has researched the basic theories and key technologies of DDR SDRAM controller design. Secondly, it has designed the hardware part of the controller, and it is mostly about the peripheral circuits. Thirdly, it has completed the design about control section of DDR SDRAM controller with hardware description language VHDL, which used the design idea of Top-To-Down and modular design method. And finally it has done simulation to the design and tested the hardware, and the wave of the simulation shows that the design completely meets the request of the design system.