Dual referenced microstrip

A machine-readable medium having stored thereon a plurality of executable instructions, the plurality of instructions comprising instructions to:

• calculate a first characteristic impedance of a dual referenced microstrip transmission line referenced to a primary reference layer;
• calculate a second characteristic impedance of the dual referenced microstrip transmission line referenced to a secondary reference layer;
• calculate an absolute value of a difference between the first and the second characteristic impedance;
• compare the absolute value of the difference to a predetermined threshold value;
• and if the absolute value of the difference is greater than the predetermined threshold value, then
• vary a physical parameter associated with the characteristic impedance between the primary and secondary reference layers until the difference is reduced to less than the predetermined threshold.

A semiconductor package having a trace designed as a dual referenced microstrip structure, comprising:

• a microstrip transmission line;
• a first conductive plane;
• a first dielectric layer provided between the microstrip transmission line and the first conductive plane;
• a second conductive plane;
• and
• a second dielectric layer provided between the first conductive plane and the second conductive plane, wherein an absolute value of a difference between a characteristic impedance of the microstrip transmission line referenced to the first conductive plane and the characteristic impedance of the microstrip transmission line referenced to the second conductive plane is less than a predetermined percentage of a nominal characteristic impedance of the microstrip transmission line.

A semiconductor package having a trace designed as a dual referenced microstrip structure, comprising:

• a microstrip transmission line;
• a first conductive plane;
• a first dielectric layer provided between the microstrip transmission line and the first conductive plane;
• a second conductive plane;
• and
• a second dielectric layer provided between the first conductive plane and the second conductive plane, wherein the characteristic impedance of a transmission line in the dual referenced microstrip structure referenced to a first reference plane minus the characteristic impedance referenced to a second reference plane is less than a predetermined value.