Abstract: Method and apparatus for optimizing data transfer over a terminated low voltage differential bus includes controlling parameters of a bus driver, a bus bias cancellation circuit, and other bus operating parameters, in response to received test results derived from test patterns sent over the bus at various transfer rates and parameter settings until optimized parameter settings within an acceptable error margin and at a highest available transfer rate are determined between a particular sending unit and a particular receiving unit on the bus.

Abstract: A driver circuit drives a digital signal onto a differential digital data transmission bus nominally biased to a negative data state during bus idle intervals by a weak negation bias current. The driver circuit overcomes the negation bias current during an active signaling sequence and comprises a signal current source and sink pair for selectively sourcing and sinking current onto positive and negative lines of the transmission bus in accordance with internally-supplied binary data levels during the active signaling sequence, and a bias override current source and sink pair for applying an override bias current to the positive and negative lines of the transmission line without interruption during the signaling sequence.

Abstract: An integrated circuit driver chip includes an on-board precision current reference source, a pull-up FET and a pull-down FET having a common node connected to a transmission line. A variable switching edge pre-driver drives at least one of the pull-up FET and pull-down FET in accordance with a push-pull fast edge mode and a wired-OR slow edge mode and includes a weak FET and a strong FET selectively connected in parallel with the weak FET to implement the push-pull fast edge mode while the weak FET operating alone implements the wired-OR slow edge mode. A switched current source selectively sources current through the pull-up FET to the transmission line in accordance with the data signal and includes a trickle current FET switch for maintaining charge stored on a parasitic capacitance when the pull-up FET is off thereby preventing current spikes during turn-on switching of the pull-up FET.

Abstract: A transmission line driver circuit has active pullup and pulldown N-type field-effect transistors (N-FETs). An input stage employs a group of N-FETs and a group of P-type field-effect transistors (P-FETs) both being dimensioned and configured to yield a variable-slope switching characteristic for both high-to-low and low-to-high signal transitions. In the N-FET group, one N-FET has the same threshold voltage as the pulldown N-FET, is diode-connected, and is also connected in parallel with a substantially smaller N-FET. In the P-FET group, one P-FET is connected in parallel with a substantially smaller P-FET, and receives a buffered version of the output signal. Both the larger N-FET and larger P-FET conduct for only part of the respective signal transition during which they are active, so that each edge has two distinct slopes. The driver circuit also includes a differential amplifier connected in feedback configuration with the pullup N-FET to limit the maximum transmission line voltage.