应用于ATE的时间测量单元设计

Design and implementation of time measuring unit applied to ATE

集成电路飞速发展对集成电路自动测试设备(ATE)中时间测量单元(TMU)的精度提出了更高的要求。针对这一问题,本文使用电子学引脚测试芯片MAX9979对数字IC施加激励和捕获响应,结合Xilinx Artix-7 FPGA内部固化的时间数字转换器(TDC)设计了一种高精度的时间测量单元。时间数字转换器采用粗、细计数结合的内插方法,粗计数由参考时钟为200 MHz的32位直接计数器实现;细计数由超前快速进位链(CARRY4)级联的延迟链构成,通过对CARRY4进行专用配置来减小其超前进位功能引起的测量误差,使用码密度校准法对延迟链进行校准。实验结果表明,TMU量程为21.475 s,平均分辨率为34.7 ps,DNL优于2.5 LSB,INL优于4.5 LSB,精度为39.7 ps。

The accuracy of time measurement units(TMU)in integrated circuit automatic test equipment(ATE)is facing higher demands due to the rapid development of integrated circuits.To cope with the increased accuracy of digital IC time parameter measurements,a high precision time measuring unit was designed in this paper,which used the electronic pin test chip MAX9979 to apply excitation and capture response,and combined with Xilinx Artix-7 FPGA internal curing time digital converter(TDC).Time-todigital converter implemented by interpolation using a combination of coarse and fine counting,the coarse counter is implemented by a 32-bit direct counter with a reference clock of 200 MHz,while the fine counter consists of a delay chain cascaded by a CARRY4 cascade,with a dedicated configuration for CARRY4 to reduce the measurement error caused by its overrun function,and the delay chain was calibrated using the code density calibration method.The experimental results show that the TMU range is 21.475 s,the average resolution is 34.7 ps,the DNL is less than 2.5 LSB,the INL is better than 4.5 LSB,and the accuracy is 39.7 ps.