Abstract: A serial communication interface driver is provided wherein current steering switches are also used to provide termination impedances. The output voltage can be produced by a voltage-dividing current path between two regulated voltages, which provides improved efficiency.

Abstract: A tunable impedance circuit is provided wherein at least one of a plurality of impedance elements is combined with at least another of the plurality of impedance elements to produce a composite impedance. A control voltage is used to determine how many of the impedance elements are to be combined to produce the composite impedance. A current that is substantially invariant over a range of operating conditions is caused to flow through a control impedance to produce the control voltage.

Abstract: A system and method is provided for providing power managed common mode logic (CML) transmitters for use with main and auxiliary power sources. Power switch circuitry comprising two PMOS transistors switches the CML transmitter output circuit between a main power source node (VDD) and an auxiliary power source node (TXRAIL). A bias circuit biases the two PMOS transistors to place the main power source voltage on the auxiliary power source node (TXRAIL) when the value of the main power source voltage is nonzero. The bias circuit also biases the two PMOS transistors to remain off when the value of the main power source voltage on the main power source node (VDD) is zero.

Abstract: A system and method is disclosed for providing a fast turn on bias circuit that permits a fast transition from an idle “power down” state to an active “power up” state in current mode logic (CML) transmitter output circuits. The invention comprises a capacitor coupled to a bias transistor and a charge switch circuit for controlling the operation of the capacitor. The capacitor has a value of capacitance that is equal in magnitude and opposite in sign to the Miller coupling capacitance in the bias transistor. The capacitor compensates for the Miller coupling capacitance within the bias transistor in less than ten nanoseconds. This permits a CML transmitter to more quickly restart the transmission of data after an active state has been initiated.