Interface circuits

A signal transmission system, comprising:

• a transmission line having first and second ends;
• a first interface circuit connected to the transmission line at its first end;
• and
• a second interface circuit connected to the transmission line at its second end;
• wherein each of the first interface circuit and the second interface circuit comprises:
• a signal line having signal, auxiliary and connection nodes defined therealong, the connection node for connection to the transmission line;
• signal-handling circuitry connected to the signal line at the signal node so that an effective capacitance of the signal-handling circuitry is experienced at the signal node;
• an auxiliary circuit connected to the signal line at the auxiliary node so that an effective capacitance of the auxiliary circuit is experienced the auxiliary node;
• a signal pair of inductors connected in series along the signal line adjacent to and either side of the signal node;
• and
• an auxiliary pair of inductors connected in series along the signal line adjacent to and either side of the auxiliary node,
• wherein:
• the signal pair of inductors are configured to have a mutual coupling defined by a coupling coefficient kS;
• the auxiliary pair of inductors are configured to have a mutual coupling defined by a coupling coefficient kA;
• for each said pair of inductors, the inductors of the pair are arranged such that a current flowing along the signal line in a given direction through one of those inductors induces a current in the other one of those inductors and flowing in the same direction along the signal line given a positive coupling coefficient;
• and
• kS has a positive value and kA has a negative value.