Patent ID: 6469519
Filing Date: 2002-10-22
Classification: G01R,H04M

Abstract:
A-loop voltage measurement circuit for producing an output proportional to the differential tip-ring voltage across tip and ring leads of a telephone wireline pair comprising:tip and ring ports, adapted to be respectively coupled to said tip and ring leads of said telephone wireline pair; a tip-ring voltage detector coupled to said tip and ring ports, and being operative to produce at a current output node thereof an output current representative of the composite of said differential tip-ring voltage and a voltage associated with internal characteristics of said tip-ring voltage detector; a differential current extraction circuit coupled to said current output node, and being operative to generate a first current component that is fractionally proportional to said output current produced at said current output node of said tip-ring voltage detector, and a second current component that is fractionally proportional to said voltage associated with internal characteristics of said tip-ring voltage detector; and an output node coupled to receive a combination of said first and second current components generated by said differential current extraction circuit and to produce a tip-ring voltage representative output current representative of only said differential tip-ring voltage.