Integrated filter tuning method and apparatus
AssigneeLSI Logic Corporation
InventorEdward Liu
Life of this patent
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Abstract
A transmission system for transmitting a signal from a host to a transmission medium is disclosed. The transmission system includes a current-mode digital-analog converter, an on-chip low-pass filter, a line driver, and output impedance control. Further, a method for transmitting a signal from a host to a transmission medium using on-chip filtering is disclosed. More specifically, an apparatus and method for providing precise control of the filter cut-off frequency at high frequencies is disclosed. The transmission system and method can be used in transmission of Ethernet signals onto an unshielded twisted pair cable. In addition, with appropriate modification, the transmission system and method can be used for transmitting ATM or other signals onto a transmission medium.
Claims30
A transmission system for transmitting a signal having predetermined frequency ranges and voltage levels representing data for a computer system, to a transmission medium, the transmission system comprising:
- a digital to analog converter operating in current mode to control signal voltage levels, the digital to analog converter receiving the signal and converting the signal from a digital format to an analog format;
- an integrated filter coupled to the digital to analog converter, the integrated filter for removing select frequency components from the signal, the filter being configured to receive the signal and output a filtered signal for provision to the transmission medium;
- and
- a tuning cell coupled to and integrated on a common substrate with the filter and the digital to analog converter for setting a cut-off frequency of the filter, the tuning cell having compensation circuitry that at least partially counteracts parasitic capacitances of the tuning cell to control signal frequency ranges.
A method for communicating data from a host to a transmission medium using an output signal having predetermined voltage levels and frequency ranges, the method comprising.
- providing a digital to analog converter operating in current mode to convert an input signal from a digital format to an analog format to control the voltage levels of the output signal;
- and
- providing an integrated filter for removing select frequency components from the input signal, thereby generating a filter signal, die integrated filter comprising a tuning cell having a damping circuit that at least partially counteracts parasitic capacities of the tuning cell to control the frequency ranges of the output signal.
An apparatus for transmitting data from a computing device to a transmission medium using an output signal having predetermined voltage levels and frequency ranges, the apparatus comprising:
- means for converting an input signal from a digital format to an analog format, the mew for converting operating in a current mode to control the voltage levels of the output signal;
- means for removing particular components of the input signal and outputting other components of the input signal, the means for removing particular components being integrated on a semiconductor substrate, the particular components being determined by a cut-off frequency;
- and
- means for seeing the cut-off frequency, at least partially incorporated on the semiconductor substrate such the means for setting the cut-off frequency includes a stabilization means that at least partially counteracts parasitic capacitances associated with the means for setting the cut-off frequency to control the frequency ranges of the output signal.
Dependencies are inferred from the claim text.