Telephonic communications – Line equalization or impedance matching
Reexamination Certificate
2006-04-18
2006-04-18
Harold, Jefferey F. (Department: 2646)
Telephonic communications
Line equalization or impedance matching
C379S399010, C379S402000
Reexamination Certificate
active
07031456
ABSTRACT:
A hybrid system with adjustable on-chip components and a method calibrating the same invariably maximizes hybrid performance despite of on- and off-chip component mismatches and imperfections. The hybrid system has a main DAC, a replica DAC, and three or four resistors. Both DACs are directly connected to digital data. An adjustable resistor is connected to the main DAC and is calibrated such that output impedance is automatically adjusted to match an off-chip load impedance Z. A replica DAC current K is calibrated for optimum DC matching in presence of Z. An adjustable capacitor C2is calibrated for slope-matching (bandwidth matching). If Z changes, the calibration procedure should be repeated for optimal performance. These three calibration mechanisms can be utilized individually or in combination. The present invention is compatible with both analog and digital echo-cancellers.
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Dyer Kenneth C.
Takatori Hiroshi
Harold Jefferey F.
Key Eye
Lumen Intellectual Property Services Inc.
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