The Design Of High-speed Signal Acquisition Card

With the development of digital signal processing of bandwidth, performances, algorithm, it’s necessary for the front-end of a signal acquisition module to put forward higher request. The key performances of the signal acquisition module includes resolution, sampling rate, sampling channel bandwidth, SNR, SFDR, etc. These performances have a intimate relationship with system scheme, circuit composition, chips’ performance, Controlling method, etc. In order to meet the design requirements of a baseband signal sampling task, this design developed a kind of data acquisition board with1Gsps sampling rate and200MHz analog signal bandwidth. The main problems of the design to solve as follows:1. Design of high-speed analog signal channel with high signal-to-noise ratio, high dynamic range and controllable amplification and attenuation;2. The high stability, high precision, low jitter clock distribution circuit design and implementation;3. The combined sampling design based on two high-speed AD chips and control logic implementation;4. Data storage circuit design based on the DDR2SDRAM SO-DIMM module and control logic implementation;5. Circuit design based on PCI local bus and control logic implementation.The innovation points of the design as follows:1. Design of independent sampling clock circuit which realized the high SNR and the accurate adjustable sampling clock;2. The DDR2SDRAM SO-DIMM module in place of the traditional chips, which realized the depth of the storage expansion;3. Digital logic design is fast reconfigurable according to system resources, sampling accuracy and internal system bandwidth.