Patent ID: 6828797
Filing Date: 2004-12-07
Classification: G01R

Abstract:
A method for measuring a test differential voltage across a first output and a second output of a transmitter integrated circuit device, the test differential voltage corresponding to a voltage across the first output and second output appearing while the device is providing an output while being subiected to voltages applied across a resistor network connected to the differential outputs, the resistor network comprising a first resistor having a value of Ra connected between the first cutout and a first voltage, a second resistor having a value of Rb connected between the second output and a second voltage, and a third resistor having a value of Rc connected between the first output and the second output, comprising the steps of:applying a first current to the first output, the first current being of a magnitude determined to correspond to a magnitude of current that would appear at the first output while the device were providing an output while being subiected to said predetermined voltages applied across said resistor network: applying a second current to the second output, the second current being of a magnitude determined to correspond to a magnitude of current that would appear at the second output while the device were providing an cutout while being subiected to said predetermined voltages applied across said resistor network: and measuring a test differential output voltage across the first output and the second output, wherein said step of applying a first current is performed by deriving the values of secondary resistors R1, R2 and R3, representing the corresponding resistor values of a Wye network equivalent to the resistor network comprising said first, second and third resistors;applying said first current having a magnitude of IOH=[1(R1+R3)&it;(R3+R2)*(R3+R3)]*[(R3+R1)*(V2)-(R3)*(V1)];andwherein said step of applying a second current is performed by applying said second current having a magnitude of IOL=[1(R1+R3)&it;(R3+R2)*(R3+R3)]*[(R3+R2)*(V1)-(R3)*(V2)].