Finisar Corporation

Finisar Corporaton

Texas Instruments Corporation

Timothy G Moran

The'linh Nguyen

Gerald L Dybsetter

Greta Light

Jason Y Miao

Georgios Kalogerakis

Stephen T Nelson

David Joseph Block

A system may include a driver circuit configured to receive a clock signal. The system may also include a first tuned circuit and a second tuned circuit. The first tuned circuit and the driver circuit may be collectively tuned according to a first frequency range. The first tuned circuit may be configured to be active when a rate of the clock signal is within the first frequency range and to be inactive when the rate is outside of the first frequency range. Further, the second tuned circuit and the driver circuit may be collectively tuned according to a second frequency range that is different from the first frequency range. The second tuned circuit may be configured to be active when the rate is within the second frequency range and to be inactive when the rate is outside of the second frequency range.

Multi-rate clock buffer

Systems and methods for controlling the modulation current of a laser included as a component of an optical transmitter, such as an optical transceiver module, are disclosed. Control of the modulation current, which affects various laser operational parameters, including extinction ratio and optical modulation amplitude, enables operation of the laser to be optimized, thereby enabling reliable transceiver performance to be achieved. In one embodiment, a method for modifying the modulation current in an optical transceiver module includes first sensing analog voltage data that proportionally relates to an actual modulation current of the laser. Once sensed, the analog voltage data are converted to digital voltage data. Using the digital voltage data, the actual modulation current of the laser is determined, then a desired modulation current is determined. Should a discrepancy exist between the actual and desired modulation currents, the actual modulation current is modified to match the desired current.

Determination and adjustment of laser modulation current in an optical transmitter

Modules and signal control circuits configured to at least partially compensate for or adjust for asymmetric rise/fall time. The circuit may include a first input node configured to receive a first data signal and a second input node configured to receive a second data signal that is complementary of the first data signal. The circuit may also include a first stage having a first node coupled to the first input node and a second node coupled to the second input node and a second stage having a first node coupled to a third node of the first stage and a second node coupled to a fourth node of the first stage. The second stage may be configured to drive a load such as a laser. The circuit may further include a third input node configured to receive a third data signal and a fourth input node configured to receive a fourth data signal that is the complementary of the third data signal. Additionally, a control stage having a first node coupled the third input node, having a second node coupled to the fourth input node, having a third node coupled to the third node of the first stage and having a fourth node coupled to the fourth node of the first stage.

Asymmetric rise/fall time and duty cycle control circuit

An amplifier stage or circuit for providing cross-point adjustment. The circuit may include a first input node configured to receive a first data signal and a second input node configured to receive a second data signal that is complementary of the first data signal. The circuit also includes a programmable first stage having a first node coupled to the first input node and a second node coupled to the second input node that is configured to adjust an amount of current provided to the first and second data signals to create a signal offset. The circuit further includes a second stage having a first node coupled to a third node of the programmable first stage and a second node coupled to a fourth node of the programmable first stage configured to provide the signal offset at a third and fourth node of the second stage to adjust the cross-point of the first and second signals.

Cross-point adjustment circuit

Embodiments disclosed herein relate to an amplifier stage or circuit for providing a signal boost. The circuit includes an emitter-follower pair and a cross coupled differential pair. The cross coupled differential pair provides a feedback signal that provides a boost to a signal output by the emitter follower pair. In some embodiments, a capacitor of the cross coupled differential pair may be adjustable in order to vary the amount of boosting provided. In other embodiments, a current source of the cross coupled differential pair may be adjustable in order to vary the amount of boosting provided.

Circuit for providing a signal boost

A laser filter circuit includes an input terminal configured to receive an input laser signal and a first filter chain configured to generate a filtered signal. The first filter chain is coupled to the input terminal and has one or more filters connected in series. Each filter includes one or more adjustable capacitor networks. An adjustable capacitor controller generates one or more capacitor switch control signals based on an operating frequency of the input laser signal. The one or more control signals are for adjusting the capacitance of the one or more adjustable capacitor networks in the first filter chain. A plurality of output terminal output the filtered signal from the first filter chain.

Circuit for filtering a laser signal

Systems and methods for regulating a current mirror. A current mirror includes mirror circuits that each include a transistor or a transistor network. A mirror circuit in the current mirror is used by a detector of an optical receiver to draw current in response to an incident optical signal on the photodiode. The transistor in the current mirror is connected with a regulating amplifier that drives a gate of the transistor. The regulating amplifier uses the drain voltage of the transistor as an input such that the amplifier's output drives the gate such that the drain voltage substantially matches a reference voltage that is also an input to the regulating amplifier. The regulating amplifier can be integrated with the current mirror and eliminates the need for an external capacitor to reduce the effects of noise on current drawn by the detector.

Regulated current mirror

An optical transceiver in which one or more bias currents provided to the laser driver are adjusted at cold temperatures such that transition speeds are reduced. A preliminary current generation circuit generates a preliminary current. In addition, a programmable cold temperature bias current compensation circuit draws a configurable amount of current from the preliminary current if the ambient temperature is below a threshold temperature to generate a final current. A laser driver bias current delivery circuit then provides at least one laser driver bias current to the laser driver. These delivered bias currents are dependent at least in part upon the final current. Accordingly, the bias currents provided to the laser current reduce the transition speed of the optical signal at low temperatures, thereby reducing jitter and electromagnetic interference, and allowing user control over the amount of compensation.

Programmable transition time adjustment mechanism

A method of filtering a differential signal. The method includes receiving the differential signal. Transitions of the differential signal are accelerated after the differential signal has passed through a cross-over point to create an accelerated differential signal. A delayed differential signal is created that is a delayed version of the accelerated differential signal delayed by a predetermined amount of time with respect to the accelerated differential signal. The accelerated differential signal is amplified to create an amplified accelerated differential signal. The delayed differential signal is amplified to create an amplified delayed differential signal. The amplified delayed differential signal and the amplified accelerated differential signal are combined to create an output signal.

Amplification circuit for driving a laser signal

A telecommunications system that includes an external memory, an internal memory and a system clock. A boot component is configured to use the clock signal generated by the system clock to load data from external memory into internal memory when the telecommunication system operates in initialization mode. The telecommunication system is configured to operate based on the loaded data in internal memory when the system operates in normal mode. Once the initialization mode is complete, the system clock may be shut down since the telecommunication system does not need the system clock to perform normal mode operations. Subsequently, the system clock may be restarted if need be. Accordingly, the system clock is generated when it is needed, but not continuously. Therefore, cross-talk between the system clock and the receive and transmit path is reduced.

Transient transceiver clock configuration

An optical transmit circuit that includes an electro-optic transducer driver and an electro-magnetic interference ('EMI') reduction filter. The EMI reduction filter is coupled to an output terminal of the electro-optic transducer driver. This allows the EMI reduction filter to receive an electrical signal from the transducer driver. The EMI reduction filter then filters out a significant portion of the EMI of concern from the electrical signal.

Electro-magnetic interference reduction filter for an optical transceiver

A circuit module having one of more digital input terminals that are capable of receiving a third input state to initiate non-standard operational modes such as might be desired during programming or testing of the module or its surrounding circuitry. For each of these special digital input terminals, there is a component that recognizes the presence of the third state applied to the corresponding input terminal. In response, the component generates a signal that causes the module to enter the non-standard operational mode. A non-standard operational mode is a mode other than the normal operational mode of the module. As an example, the non-standard operational mode might be a testing or programming mode that is encountered prior to even shipping the module to a consumer.

Use of a third state applied to a digital input terminal of a circuit to initiate non-standard operational modes of the circuit

Systems and methods for continuously compensating a modulation current of a laser. A temperature compensation circuit has circuitry with a positive temperature coefficient connected with circuitry having a negative temperature coefficient. The temperature compensation circuit generates a temperature dependent reference current that is mirrored to a gain circuit. The gain circuit provides variable gain. The gain circuit also provides inputs that can be set to select a particular gain. The output of the gain circuit, which changes as temperature affects the reference current, is used to compensate the modulation current of the laser.

Continuous temperature compensation for a laser modulation current

An eye safety detection circuit for use in a laser transmitter. The eye safety detection circuit shuts the laser down if the laser is emitting excessive optical energy to the point of being unsafe to a user. The eye safety detection circuit includes a laser current detection circuit that is configured to detect when there is a potential that the laser is emitting light at levels that exceed a predetermined threshold. If the laser were to immediately turn off under this condition, the laser may be turned off prematurely. Instead, the eye safety detection circuit includes a timer circuit that causes the laser to cease operation only after one or more such conditions have been met for a predetermined period of time.

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San Jose, CA, United States of America

Timothy G Moran