Abstract: The present invention is directed toward a communications channel comprising a link level protocol, a driver, a receiver, and a canceller/equalizer. The link level protocol provides logic for DC-free signal encoding and recovery as well as supporting many features including CRC error detection and message resend to accommodate infrequent bit errors across the medium. The canceller/equalizer provides equalization for destabilized data signals and also provides simultaneous bi-directional data transfer. The receiver provides bit deskewing by removing synchronization error, or skewing, between data signals. The driver provides impedance controlling by monitoring the characteristics of the communications medium, like voltage or temperature, and providing a matching output impedance in the signal driver so that fewer distortions occur while the data travels across the communications medium.

Abstract: A variable communication systems comprising a plurality of transceivers and a control circuit connected to the transceivers to configure the transceivers to operate in a bi-directional mode and a uni-directional mode at different times using different transfer methods to transfer data.

Abstract: A level shifting circuit which can be implemented as part of a bipolar ECL integrated circuit, provides reliable switching and level shifted output suitable for driving a low voltage CMOS integrated circuit. The circuit includes a level shifting circuit which is connected to trigger a high gain positive feedback bootstrap circuit to reliably ensure switching even under poor signal conditions. An output taken from one of the switched pair is allowed to go to V.sub.CC, 0 volts, or is clamped by a clamping circuit to -3.3 volts, representing the two output states suitable for driving inverted rail CMOS circuitry.

Abstract: The present invention provides a voltage reference level using a bipolar output transistor to provide a reference voltage on a reference output line. A control circuit is used for varying the current to the base of the output transistor in response to the load on the reference output line. In addition, the control circuit provides the reference level to the output transistor. The MOS control circuit and the bipolar output transistor are fabricated on the same chip using a BICMOS process. The voltage reference provided by the control circuit is derived from a voltage level provided by a resistor coupled between the positive voltage supply and a current source.

Abstract: The present invention provides an ECL EPROM circuit which uses a MOS memory cell. The invention includes a technique for programming the memory cell using MOS voltage levels, and also includes circuitry for reading the memory cell at ECL voltage levels. Thus, the programming and reading paths are split to give the ease of programming and the reprogrammability of MOS EPROM devices combined with the reading speed of PROM devices using ECL voltage levels. In one embodiment, two parallel paths are provided to a memory cell to enable it to separately receive reading and writing (programming) signals. The reading path employs ECL components for reading the cell, while the writing path contains MOS components for programming and verifying the cell. The memory cell itself contains a MOS memory element, an ECL pass element, and a sense element coupling the MOS memory element to the ECL pass element.

Abstract: A power transition circuit protects a bipolar-CMOS (BiCMOS) circuit during power transitions. Reference signals proportional to the voltage supplied to the protected circuit are monitored, and the power transition circuit determines from the voltage differential between the reference signals whether a power transition is occurring. If a transition is present, the transition circuit disables the protected BiCMOS circuit for as long as the power transition exists. An independent input signal allows the power transition circuit to disable the protected BiCMOS circuit in response to other conditions.

Abstract: A biCMOS interface circuit receives a plurality of incoming signals at a first level and supplies a plurality of output signals at a second level. The interface circuit establishes control voltages which are used to maintain an identical trip point in each of a plurality of translator circuits. Generally, the trip point is set at midway between the "high" and the "low" levels of the incoming logic signal. The control voltages assure reliable performance over a wide operating environment.