The architecture of carry chains in Field-Programmable Gate Array(FPGA) is introduced in this paper. The propagation delay time of the rising and falling edges in the carry chains are calculated according to the archi...The architecture of carry chains in Field-Programmable Gate Array(FPGA) is introduced in this paper. The propagation delay time of the rising and falling edges in the carry chains are calculated according to the architecture and they are predicted not equal in most cases. Tests show that the measuring results of the propagation delay time in EP3C120F484C8 N series FPGA of Altera are in line with the inference. The difference of propagation delay time results in different accuracies of Time-to-Digital Converter(TDC). This phenomenon shall be considered in the design of TDC implemented in FPGA. It can ensure better accuracy.展开更多
采用FPGA芯片进行数字信号处理时常需要数控振荡器(Numeric Control Oscillator,NCO)产生各种不同频率的时钟,然而随着工程中对NCO的工作频率需求的提高,实现NCO的加法器将会有过长的进位链,这样就限制了加法器的运行频率不能过高。为...采用FPGA芯片进行数字信号处理时常需要数控振荡器(Numeric Control Oscillator,NCO)产生各种不同频率的时钟,然而随着工程中对NCO的工作频率需求的提高,实现NCO的加法器将会有过长的进位链,这样就限制了加法器的运行频率不能过高。为了解决这一限制与需求的矛盾,采用一种基于预进位链优化的改进方法。经过对无预进位NCO、一级预进位NCO和二级预进位NCO的时序分析和实测数据进行对比,结果表明这种方法产生的NCO频率指标满足设计要求,可以将NCO的工作频率提高70.53%。展开更多
文摘The architecture of carry chains in Field-Programmable Gate Array(FPGA) is introduced in this paper. The propagation delay time of the rising and falling edges in the carry chains are calculated according to the architecture and they are predicted not equal in most cases. Tests show that the measuring results of the propagation delay time in EP3C120F484C8 N series FPGA of Altera are in line with the inference. The difference of propagation delay time results in different accuracies of Time-to-Digital Converter(TDC). This phenomenon shall be considered in the design of TDC implemented in FPGA. It can ensure better accuracy.
文摘采用FPGA芯片进行数字信号处理时常需要数控振荡器(Numeric Control Oscillator,NCO)产生各种不同频率的时钟,然而随着工程中对NCO的工作频率需求的提高,实现NCO的加法器将会有过长的进位链,这样就限制了加法器的运行频率不能过高。为了解决这一限制与需求的矛盾,采用一种基于预进位链优化的改进方法。经过对无预进位NCO、一级预进位NCO和二级预进位NCO的时序分析和实测数据进行对比,结果表明这种方法产生的NCO频率指标满足设计要求,可以将NCO的工作频率提高70.53%。
