Micrel, Incorporated

Bernd Neumann

Thomas S Wong

George W Brown

Maik Pohland

Uwe Biswurm

Dieter Kuehnel

Dieter Kühnel

A laser driver circuit having a differential circuit and an output circuit includes a control circuit receiving a regulated supply voltage that also supplies the differential circuit as an input signal. The control circuit generates a feedback voltage across a first resistor to cause a first current to flow in the first resistor having a current value equal or proportional to the modulation current value. The laser driver circuit includes an operational amplifier receiving the feedback voltage and a reference voltage indicative of a desired modulation current value and to generate the regulated supply voltage. The control circuit and the operational amplifier form a feedback control loop to adjust the regulated supply voltage to regulate the feedback voltage to be equal to the reference voltage, thereby regulating the modulation current value to the desired modulation current value.

High compliance laser driver circuit

A noise discriminator circuit and a noise discrimination method in a burst mode receiver is configured to determine the validity of an incoming burst signal by analyzing the timing of the signal edges of incoming signal to look for a time duration conforming to the preamble data bits of a valid burst signal. In one embodiment, the noise discriminator circuit and method analyze the time duration between signal edges of the same pulse of an incoming signal. In another embodiment, the noise discriminator circuit and method analyze the time duration between a first set of pulses of an incoming signal and the time duration between signal edges of a second set of pulses of the incoming signal. When the time durations are within a given time range relating to a predetermined timing separation of a valid burst signal, the incoming signal is validated as a valid burst signal.

Noise discriminator for passive optical network burst mode receiver

Noise discriminator for enhanced noise detection in a passive optical network burst mode receiver

An overcurrent protection circuit for a current setting circuit is disclosed herein that prevents a user-selectable current from exceeding a current limit when an incorrect current selecting component (or current selecting circuit) is connected to an external control pin of a package by the user, or when the control pin is inadvertently grounded. The protection circuit senses a current (A*Iset) mirrored from the user-set current (Iset). If the mirrored current is above a threshold, the protection circuit limits the Iset current to be at or below a current limit level. In one embodiment, the protection circuit comprises a transistor that turns on when the mirrored current exceeds a threshold, and the transistor shunts control current from a series transistor generating the user-set current Iset.

Overcurrent protection circuit when setting current using a package control pin

A fail-safe differential receiver having a differential amplifier adapted to receive first and second differential input signals and generate a differential voltage. A peak detector is coupled to the differential amplifier for generating a detect signal and a comparator is coupled to the peak detector for comparing the detect signal to a threshold voltage and providing a comparison signal. A directing circuit is coupled to the differential amplifier for receiving the first and second differential input signals and is coupled to the comparator for receiving the comparison signal. An output amplifier is coupled to the directing circuit. The directing circuit selectively directs the first and second differential input signals to the output amplifier as a function of the value of the comparison signal from the comparator.

Circuit and method for providing a fail-safe differential receiver

A multiplexer circuit for selecting one of first and second input signals based on a first input select signal includes a multiplexer, a control circuit and an enable buffer. The multiplexer selects one of the first and second input signals based on a second input select signal generated by the control circuit and provides a second output signal. The control circuit receives the second output signal and the first input select signal to generate the second input select signal and an enable signal where the signals have transitions synchronized to the transitions of the second output signal. The enable buffer operates to allow or disallow the second output signal to be passed as the output signal of the multiplexer circuit in response to the enable signal. The multiplexer circuit operates to eliminate runt pulse generation during the switching over of the input signals to provide an error-free output data stream.

Runt-pulse-eliminating multiplexer circuit

A multiplexer is disclosed. The multiplexer comprises a first input and a first channel coupled to the first input. The multiplexer further includes a second input and a second channel coupled to the second input. Finally, the multiplexer includes an output coupled to the first and second channels, wherein a coupling capacitance of an inactive one of the first and second channels is not coupled directly to the output. A method and system in accordance with the present invention reduces crosstalk and jitter in a multiplexer by eliminating the coupling capacitance between an inactive input and the output. In so doing, there is significantly better isolation between channels thereby minimizing the aforementioned cross-talk and jitter.

Growing community of inventors

Muellrose, Germany

Bernd Neumann