【通信应用笔记】ISDN接口保护.pdf AN585 APPLICATION NOTE ISDN INTERFACE PROTECTION INTRODUCTION The choice of a suitable protection device for an ISDN line interface requires consideration of a parameter which is not critical in analogue line applications: the parasitic capacitance that the device introduces. Be- cause of the high data rates used, parasitic capacitances must be minimized in order to ensure correct signal transmission. In particular, attention must be paid to the capacitance imbalance in the line which can cause considerable signal degradation. Such imbalance most frequently results from the presence of common-mode prote……