Method and apparatus for providing self-terminating signal lines

A self-terminating module comprising:

• an internal non-self-terminating module including a data input circuit;
• an internal termination circuit directly connected to the internal non-self-terminating module for at least partially terminating a signal line when the self-terminating module is coupled to the signal lines;
• and
• a pass circuit coupled between the internal termination circuit and the internal non-self-terminating module, the pass circuit for allowing a signal to travel between the internal termination circuit and the internal non-self-terminating module in response to a control signal.

A self-terminating module comprising:

• an internal non-self-terminating module including a data input circuit;
• an internal termination circuit directly connected to the internal non-self-terminating module for at least partially terminating a signal line when the self-terminating module is coupled to the signal lines;
• a pass gate having a control terminal, the pass gate, for coupling between the internal termination circuit and the internal non-self-terminating module, and for allowing a signal to travel between the internal termination circuit and the internal non-self-terminating module in response to a control signal;
• and
• a delay circuit coupled to the control terminal of the pass gate for supplying the control signal to the control terminal for a predetermined time period after a predetermined delay in response to a trigger signal.

A signal network comprising:

• a signal line having a loaded line characteristic impedance;
• a plurality of self-terminating modules coupled to the signal line, each self-terminating module terminating the signal line with a terminating impedance;
• wherein each self-terminating module comprises an internal non-self-terminating module, and an internal termination circuit directly connected to the internal self-terminating module for at least partially terminating the signal line when the self-terminating module is coupled to the signal line;
• said terminating impedance of each self-terminating module selected to reduce loading of the signal line by the plurality of self-terminating modules;
• and
• wherein the terminating impedance of each self-terminating module is selected according to the formula:
• ZM≧(L/ (C+C) )½
• where ZM is the terminating impedance of each self-terminating module, L is the inductance and C is the capacitance of the signal line prior to coupling the self-terminating modules thereto, and CM is the additional capacitance component in parallel with the capacitance C when the self-terminating modules are coupled to the signal line.

A method of terminating a signal line comprising:

• providing a signal line;
• providing a plurality of self-terminating modules, each self-terminating module comprising an internal non-self-terminating module directly connected to an internal termination circuit for terminating the signal line with a terminating impedance so as to reduce loading of the signal line when the plurality of self-terminating modules are coupled to the signal line;
• coupling the plurality of self-terminating modules to the signal line;
• determining a rise time and a fall time of a signal to be transmitted on the signal line;
• determining a round trip travel time of the signal between an end of the signal line and the self-terminating module closest to the end of the signal line;
• and
• connecting an external termination circuit to the end of the signal line if the round trip travel time of the signal is greater than either the rise time or the fall time of the signal.