Abstract: An apparatus and method is provided for sensing which faults have occurred in a laser control system, as well as trapping and identifying the first fault occurrence. The apparatus includes an integrated circuit in which a mask register is set by means of a micro-controller or a host system to select which fault sources are to be recorded. A status bit register in which the fault indications are stored can also be interrogated by the micro-controller or a host system. A settable first fault status register determines whether every fault or only the first fault gets recorded.

Abstract: An arrangement to enable automatic baud rate speed negotiation between transceivers having different operating speed characteristics is implemented. When an event indicative of a possible baud rate mismatch occurs, control signals are generated and used to trigger a baud rate negotiation procedure. In the baud rate negotiation procedure, a predetermined pattern is transmitted, the baud rate of the respective transmitting transceiver is decoded, and the decoded baud rate is used to select an appropriate filtering for the transceiver.

Abstract: The invention relates to a pulse shaping circuit for shaping electrical pulses driving an optical transmitter, e.g. a lased diode or an LED, and for providing electrical pulses having independently height and width-adjustable peaking at the edges thereof. The pulse shaping circuit of the present invention includes a high-pass RC filter with a differential output for providing transient electrical pulses from an input differential pulse, an adjustable voltage offset generating circuit, a differential amplifier for adjusting the width of the transient electrical pulses in dependence on the adjustable voltage offset, and a variable-gain current-steering amplifier for producing transient pulses with independently adjustable width and height.

Abstract: Techniques and apparatus for testing phase rotators for detecting defective tap weights are provided. Phase rotator test logic may include a master phase rotator to cycle the phase of a clock signal distributed to operational phase rotators through an entire cycle of phases (e.g., an entire 360 degree rotation). Each operational phase rotator should respond with an equal but opposite phase shift in order to maintain phase lock. Thus, after sweeping, each tap weight is exercised, which may help ensure defective tap weights in any (e.g., quadrant) are detected during testing.

Abstract: Techniques and apparatus for testing jitter tolerance of a device are provided. Jitter control logic within a device may include a master phase rotator to rapidly adjust the phase of a clock signal to simulate jitter in a data stream received by the device. For some embodiments, the rate, magnitude, and signature (or waveform shape) of the phase adjustments may be controlled to simulate high frequency jitter. Errors in received data packets may be monitored while simulating this jitter (e.g., as part of a built in self test) to test the jitter tolerance of a device under test.