The Design Of Four-channel MRI Digital Receiver

With the development of parallel imaging and phased array coils in magnetic resonance imaging systems,multi-channel receivers have doubled the data rate,and high data rates have placed new demands on the implementation of new spectrometer interfaces.The new high-speed serial interface is widely used in high-speed interconnection fields such as data centers,supercomputers,and enterprise core servers due to its high density,high efficiency,and low power consumption.Optical fiber communication has excellent electromagnetic interference resistance,and has an exceptional advantage for the complex electromagnetic environment of the magnetic resonance systemThis thesis focuses on the key part of the development of a new "magnetic resonance fiber imaging system":a four-channel digital receiver.The receiver uses a radio frequency direct sampling structure.Independent four-channel reception on a single half-height,half-height standard PCI Express x 1 board,supporting up to 125MHz 16bit sampling per channel,digital IF signal processing based on FPGA,onboard dual SFP interface,enabling 3.125Gbps data upload.Introduces the mainstream digital receiver architecture,and analyzes the receiver-related design requirements for the 1.5T imaging system,finished the hardware design of the receiver board,and the actual circuit was debugged and analyzedBased on the background of the existing digital magnetic resonance digital receivers,the bandwidth of the imaging signals of different systems varies greatly.A receiver developed to meet the needs of large signal bandwidth causes a waste of effective bandwidth of the system when sampling a small bandwidth signal,a reduction in the signal-to-noise ratio of the imaging signal,and redundancy of the data after down-conversion,and reduce the data bus bandwidth utilization between the receiver and the spectrometer,With the development of technologies such as parallel imaging and phased array coils,the multi-channelization of receivers has doubled the data rate,and the problem of reduced bandwidth utilization of such bus transmissions has become more serious.Aiming at the characteristics of narrow band and large dynamic range of magnetic resonance signals,a variable bandwidth digital down-conversion design method with decimation rate can be programmed online and more flexible and universal.The design of each module and FPGA implementation are analyzed in detail.Finally,the function verification and resource loss analysis are carried out,which provides a highly flexible variable bandwidth DDC solution for the design of magnetic resonance imaging receiving system.