INTERCONNECTION STRUCTURE FOR CROSSTALK REDUCTION TO IMPROVE OFF-CHIP SELECTIVITY.

摘要

TO REDUCE CROSSTALK IN REENTRANT OFF-CHIP RF SELECTIVITY,DIFFERENTIAL CIRCUITS (402,415),TRANSMISSION LINES (423,424), AND OFF-CHIP FILTERS (422) ARE USED IN A STRUCTURE THAT BALANCES THE PARASITIC CAPACITANCES ASSOCIATED WITH ALL OF THE DIFFERENTIAL ELEMENTS.THE STRUCTURE INCLUDES A SUBSTRATE (409) WITH A DIFFERENTIAL GENERATING CIRCUIT (402) AND A RECEIVING CIRCUIT (415).TWO DIFFERENTIAL TRANSMISSION LINES (423,424),EACH WITH CONSTANT CHARACTERISTIC IMPEDANCE, AND EACH WITH BALANCED CAPACITANCE TO GROUND,BOTH BEING CLOSELY SPACED FOR SOME DISTANCE,COUPLE THE CIRCUIT (402,415) TO CLOSELY SPACED TERMINATING PADS (403). A GROUND PLANE (412) IS SHARED UNDER BOTH TRANSMISSION LINES (423,424). A SECOND SUBSTRATE (408) HAVING A REENTRANT RF PATH (406) WITH THE FIRST SUBSTRATE (409) CONTAINS AN RF FUNCTION SUCH AS A FILTER OR A DELAY LINE.FIG. 4