Method and apparatus for impedance matching in transmission circuits using tantalum nitride resistor devices
View Patent ↗A method for trimming impedance matching devices in high-speed circuits includes determining an electrical parameter associated with a first tantalum nitride (TaN) resistor used as an impedance matching device in the circuit under test, and comparing the determined electrical parameter associated with the first TaN resistor to a desired design value of the electrical parameter. The resistance value of the first TaN resistor is altered by application of a trimming voltage thereto, wherein the trimming voltage is based on a voltage-resistance characteristic curve of the first TaN resistor. It is then determined whether the altered resistance value of the first TaN resistor causes the electrical parameter to equal the desired design value thereof, and the altering of the resistance value of the first TaN resistor by application of a trimming voltage is repeated until the electrical parameter equals the desired design value thereof.
1. A high-speed transmission circuit, comprising:
a pair of tantalum nitride (TaN) resistors configured as impedance matching devices in opposing legs of a differential driver device formed on a chip; and
said pair of TaN resistors configured so as to have an alterable resistance value thereof upon application of a trimming voltage thereacross, said trimming voltage based on a voltage-resistance characteristic curve of the TaN resistors;
wherein said trimming voltage used for altering the resistance of the first and second TaN resistors exceeds a designed operational voltage thereacross, and wherein said pair of TaN resistors are configured to receive said trimming voltage applied thereto through an external testing device with respect to said chip.