Self adjusting transmission line drivers for high performance systems
AuthorPatel, Hitesh Narhari, 1970-
AdvisorPalusinski, Olgierd A.
MetadataShow full item record
PublisherThe University of Arizona.
RightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
AbstractOutput impedance matching for transmission line drivers is not easy to implement due to unavoidable process tolerances. An automatic system for adjusting the output impedance of fast CMOS drivers, on one chip, is described. The output impedance of all identical drivers is adjusted to match the impedance at the input of a reference transmission line, equal in geometry to the lines connected to the other drivers, by a circuit for measuring and correcting the mismatch between the output impedance of one of the drivers, taken as reference and dedicated for this purpose. The voltage measured at the far end of the reference line is sent to a differential amplifier where it is compared with the supply voltage of the final driving stage. According to the comparison result at specific time intervals, a signal is supplied to the regulator which supplies power to the penultimate driving stage, thereby controlling the resistance of the driver to match the line impedance. Simulations have shown that the percentage deviations of the far-end line voltage is approximately 3% for this design compared to a system without feedback which has a far-end line voltage deviation of approximately 18%.