A data transmission system (100; 200; 300) comprising: a signal line (101; 201; 301) for carrying a data signal; a ground line (103; 201; 301) for connecting to ground; and a first path Shockley diode (104; 204; 504; 604; 704; 804; 904; 1000; 1204) having a cathode (108; 508; 1058; 1258) and an anode (106; 506; 1059; 1259), wherein the cathode is connected to the ground line and the anode is connected to the signal line, wherein the first path Shockley diode comprises an outer p-doped region (522; 628, 641; 722; 922; 1028, 1030; 128, 1241), an inner n-doped region (520; 638; 720; 820; 920; 1046, 1048; 1220), an inner p-doped region (518; 632; 718; 818; 918; 1042, 1044; 1218), and an outer n-doped region (516; 637, 624; 716; 916;1024, 1026; 1216), wherein the outer p-doped region comprises a first subregion and a second subregion, wherein the doping level of the first subregion is higher than the doping level of the second subregion, wherein the inner n-doped region comprises a third subregion and a fourth subregion, wherein the doping level of the third subregion is lower than the doping level of the fourth subregion, wherein the inner p-doped region comprises a fifth subregion and a sixth subregion, wherein the doping level of the fifth subregion is higher than the doping level of the sixth subregion, and wherein the outer n-doped region comprises a seventh subregion and an eighth subregion, wherein the doping level of the seventh subregion is lower than the doping level of the eighth subregion, wherein a first PN junction is provided between the sixth subregion of the inner p-doped region and the neighbouring seventh subregion of the outer n-doped region, wherein a second PN junction is provided between the fourth subregion of the inner n-doped region and the neighbouring fifth subregion of the inner p-doped region, and wherein a third PN junction is provided between the third subregion of the inner n-doped region and the neighbouring second subregion of the outer p-doped region. a signal line (101; 201; 301) for carrying a data signal; a ground line (103; 201; 301) for connecting to ground; and a first path Shockley diode (104; 204; 504; 604; 704; 804; 904; 1000; 1204) having a cathode (108; 508; 1058; 1258) and an anode (106; 506; 1059; 1259), wherein the cathode is connected to the ground line and the anode is connected to the signal line, wherein the first path Shockley diode comprises an outer p-doped region (522; 628, 641; 722; 922; 1028, 1030; 128, 1241), an inner n-doped region (520; 638; 720; 820; 920; 1046, 1048; 1220), an inner p-doped region (518; 632; 718; 818; 918; 1042, 1044; 1218), and an outer n-doped region (516; 637, 624; 716; 916;1024, 1026; 1216), wherein the outer p-doped region comprises a first subregion and a second subregion, wherein the doping level of the first subregion is higher than the doping level of the second subregion, wherein the inner n-doped region comprises a third subregion and a fourth subregion, wherein the doping level of the third subregion is lower than the doping level of the fourth subregion, wherein the inner p-doped region comprises a fifth subregion and a sixth subregion, wherein the doping level of the fifth subregion is higher than the doping level of the sixth subregion, and wherein the outer n-doped region comprises a seventh subregion and an eighth subregion, wherein the doping level of the seventh subregion is lower than the doping level of the eighth subregion, wherein a first PN junction is provided between the sixth subregion of the inner p-doped region and the neighbouring seventh subregion of the outer n-doped region, wherein a second PN junction is provided between the fourth subregion of the inner n-doped region and the neighbouring fifth subregion of the inner p-doped region, and wherein a third PN junction is provided between the third subregion of the inner n-doped region and the neighbouring second subregion of the outer p-doped region.