Pulse or digital communications – Cable systems and components
Reexamination Certificate
1999-10-29
2001-12-18
Chin, Stephen (Department: 2634)
Pulse or digital communications
Cable systems and components
C375S286000, C375S296000
Reexamination Certificate
active
06332004
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to transmission systems for transmitting analog data on an unshielded twisted pair (UTP) of wires. More specifically, this invention is directed to an integrated gigabit Ethernet transmitter.
The past few years has witnessed an almost exponential growth in the extent of high speed data networks, and the data transmission speeds contemplated over such networks. In particular, bidirectional data transmission in accordance with the various Ethernet network protocols, over unshielded twisted pair (UTP) wiring, has emerged as the network implementation of choice for general commercial LAN installations as well as for some of the more prosaic residential and academic applications.
Local Area Networks (LAN) provide network connectivity for personal computers, workstations and servers. Ethernet, in its original 10BASE-T form, remains the dominant network technology for LANs. However, among the high speed LAN technologies available today, Fast Ethernet, or 100BASE-T, has become the leading choice. Fast Ethernet technology provides a smooth, non-disruptive evolution from the 10 megabits per second (Mbps) performance of the 10BASE-T to the 100 Mbps performance of the 100BASE-T. The growing use of 100BASE-T connections to servers and desktops is creating a definite need for an even higher speed network technology at the backbone and server level.
The most appropriate solution to this need, now in development, is Gigabit Ethernet. Gigabit Ethernet will provide 1 gigabit per second (Gbps) bandwidth with the simplicity of Ethernet at lower cost than other technologies of comparable speed, and will offer a smooth upgrade path for current Ethernet installations. With increased speed of Gigabit Ethernet data transmission, it is evident that EMI emission and line reflections will cause the transmitted signal to become substantially impaired in the absence of some methodology for filtering the transmitted data.
Therefore, there is a need for an integrated transmitter in a data transmission system for pulse shaping digital input data and reducing EMI emissions, implemented with relatively simple circuitry.
SUMMARY OF THE INVENTION
An analog discrete-time filter, integrated with a digital-to-analog converter (DAC) for use in a current-mode transmission line driver, provides EMI emission suppression. A multiplicity of output cells produce an output signal that is responsive to a plurality of digitized input data samples. A timing circuit generates timing signals for dividing each digitized input data sample into a first time segment and a second time segment. A control logic connected to each output cell generates control signals to drive each output cell to produce a portion of the output signal for the first time segment and the full output signal for the second time segment. In one embodiment, the first and second time segments are each half of the input data rate period and the portion of the output signal is equal to one half of the output signal.
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Al-Beshrawi Tony
Broadcom Corporation
Chin Stephen
Christie Parker & Hale LLP
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