Finisar Corporation

Philip D Shapiro

Daniel K Case

Darin James Douma

The'linh Nguyen

William R Freeman

The' Linh Nguyen

Linda Liu

The&prime; Linh Nguyen

An optoelectronic transceiver is provided that includes a laser driver in communication with an optical transmitter. The laser driver includes an operational amplifier having three stages and connected with an optical transmitter. The first stage includes a differential amplifier that receives a reference voltage input, corresponding to a desired magnitude of the optical transmitter voltage, and an optical transmitter voltage input, representing an optical output strength of the optical transmitter, and having transconductance that increases exponentially as a difference between the reference voltage and the optical transmitter voltage increases. The differential amplifier generates an output current based on the inputs. The second stage integrates the output current to generate a first output voltage. Finally, the third stage is configured to receive as input the first output voltage to generate a second output voltage approximately equal to the first output voltage, the second output voltage controlling an optical transmitter bias current.

Operational amplifier for optical transceiver

The method and apparatus for monitoring a photo-detector generates a highly compliant mirror current across a broad range of photo-detector current levels. The apparatus for monitoring includes: a pair of bipolar transistors and a first non-linear isolation element. The pair of transistors are connected in a mirror configuration with a sense transistor one of the pair of transistors sensing a photo-detector current and with a mirror transistor one of the pair of transistors mirroring the photo-detector current with a mirror current. The first non-linear isolation element has at least two terminals a first of which couples to the collector of the mirror transistor. The first non-linear isolation element exhibits a non-linear voltage drop between the at least two terminals in response to varying levels of the mirror current to improve compliance between the mirror current and the detector current. Methods and means for monitoring a photo-detector are also disclosed.

Method and apparatus for monitoring a photo-detector in an optical transceiver

The optoelectronic device includes a photo diode and an amplifier, which amplifies output of the photo diode. The amplifier includes an input stage and an output stage. In one embodiment, the input stage has a series connection to a resistor, which is connected to a ground. The output stage has a connection to ground that does not overlap the series connection. In another embodiment, the input stage has a first connection to a bypass capacitor, which is connected to a power source. The output stage has a separate, second connection to the capacitor, which prevents high frequencies from flowing between the input stage and said output stage via a connection to the power source.

Transimpedance amplifier assembly with separate ground leads and separate power leads for included circuits

The present invention relates generally to laser diodes, and particularly to an operational amplifier able to switch laser diodes on and off quickly without adversely affecting data transmission by the laser diodes. A differential amplifier included in an operational amplifier has a high transconductance when a laser diode is first turned on and a low, near constant transconductance when the laser diode is transmitting data. The operational amplifier is preferably incorporated in optoelectronic transceivers used in passive optical networks. Switching laser diodes on and off quickly enables more efficient use of network bandwidth in such passive optical networks.

System for controlling bias current in laser diodes with improved switching rates

A signal processing circuit using positive feedback while keeping the open loop gain of the circuit less than 1 to avoid oscillation. The circuit includes a floating signal source, a low gain amplifier, a feedback element, and a second stage circuit. The floating signal source produces a voltage that is impressed across the feedback element by the feedback system. The feedback element processes the voltage into an output current. The output current is passed through an output current node to the second stage circuit where the output current can be used as a current reference or be further processed. The output from the low gain amplifier may be used as a voltage output node that provides a voltage that is an amplification of the voltage produced by the floating signal source. The signal processing circuit may be embedded in another circuit, including additional stages of the signal processing circuit.

Signal processing circuit for floating signal sources using positive feedback

A precision GaAs low-voltage DC amplifier includes a level shift circuit, an amplifier and a first and a second bias control circuit. The level shift circuit shifts an input signal to generate a level shifted input signal, whose bias level is controlled by a first bias control voltage. The amplifier amplifies the level shifted input signal to generate an output signal. The bias level of the output signal is controlled by a second bias control voltage. The first bias control circuit insures that the first bias control voltage varies as necessary with temperature to hold constant the bias level of the level shifted input signal. The second bias control circuit insures that the second bias control voltage varies as necessary with temperature to hold constant the bias level of the output signal.

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Palo Alto, CA, United States of America

Philip D Shapiro