Inphi Corporation

Netlogic Microsystems, Inc

Halil Cirit

Karthik S Gopalakrishnan

Jorge Pernillo

Karim Vincent Abdelhalim

Michael Q Le

Stefanos Sidiropoulos

Pulkit Khandelwal

Ravindran Mohanavelu

Lawrence Tse

Karthik Raviprakash

The present invention relates to telecommunication techniques and integrated circuit (IC) devices. In a specific embodiment, the present invention provides a laser deriver apparatus that includes a main DAC section and a mini DAC section. The main DAC section processes input signal received from a pre-driver array and generates an intermediate output signal. The mini DAC section provides a compensation signal to reduce distortion of the intermediate output signal. The intermediate output signal is coupled to output terminals through a cascode section and/or a T-coil section. There are other embodiments as well.

CMOS externally modulated laser driver

The present invention is directed to communication systems and electrical circuits. More specifically, an embodiment of the present invention provides a termination circuit that includes a programmable gain attenuation section, a T-coil section, and a termination resistor. The characteristic resistance of the programmable gain attenuation section matches the resistance of the termination resistor. There are other embodiments as well.

Techniques for programmable gain attenuation in wideband matching networks with enhanced bandwidth

Non-ideal downstream loading of a differential driver in a single ended circuit driving a communications laser&#x2014;e.g., Electro absorption Modulated Laser (EML)&#x2014;may be compensated by deploying a second matching network at the non-functional (terminated) driver output node. Certain embodiments may further compensate for distortion arising from circuit non-ideality, by introducing a laser replica downstream of the second matching network to mimic electrical properties of the laser. Embodiments may sufficiently compensate for downstream circuit non-ideality to allow replacing the bulky choke inductor of a bias tee, with a resistor. Substituting a resistor for a more complex inductor structure can simplify design and fabrication of the single-ended driver circuit, and also reduce footprint by eliminating area formerly occupied by the choke inductor. Embodiments may be particularly suited to bridge integration with other system components undergoing design migration toward double-ended modulator circuit architectures featuring a differential driver.

Configurable laser modulator driver and output matching network

The present invention is directed to communication systems. According to embodiments of the present invention, a communication system includes at least two communication lanes and a skew management module. The skew management module generates a control current based on output test patterns of the two communication lanes. The control current is integrated and compared to a reference voltage by a comparator, which generates an analog offset signal. A PLL of one of the communication lanes generates a corrected clock signal that is adjusted using the analog offset signal to remove or adjust the skew between the communication lanes. The corrected clock signal is used for output data. There are other embodiments as well.

Skew management for PAM communication systems

The present invention is directed to communication systems. More specifically, embodiments of the present invention provide a technique and system thereof for performing eye modulation. Eye modulation is performed at the transmission side of a PAM communication system to compensate for distortion and non-linearity and generate an output waveform. Spacing among eye levels is adjusted by performing symmetric modulation using &#x3b1; parameter and asymmetric modulation using &#x3b2; parameter. A correction module measures the output waveform and sends feedback signals to a control module to adjust the &#x3b1; parameter and the &#x3b2; parameter. There are other embodiments as well.

Eye modulation for pulse-amplitude modulation communication systems

Embodiments of circuits and methods are described for decreasing transmitter waveform dispersion penalty (TWDP) in a transmitter. A data stream is received for transmission across a channel and a main data signal is generated from the data stream. At least two cursor signals are generated where each of the at least two cursor signals are shifted at least a portion of a clock period from the main data signal. The at least two cursor signals are subtracted from the main data signal to generate an output data signal with improved TWDP. Other embodiments include generating a main data signal, a pre-cursor signal shifted on previous clock cycle relative to the main data signal, and a post-cursor signal Shifted one subsequent clock cycle relative to the main data signal. The pre and post cursor signals are subtracted from the main data signal to generate an output data signal.

Systems, circuits and methods for filtering signals to compensate for channel effects

Methods, systems, and circuits cancel a reflection on a channel. A main signal conditioning module improves the quality of a signal for transmission on a channel. In addition, a reflection cancellation module generates a signal that cancels reflections generated on the channel in order to improve the quality of the transmitted signal for a receiver. A summer combines an output signal from the main signal conditioning module and the reflection cancellation module.

Methods, systems and circuits for cancelling reflections on a channel

Transmitter waveform dispersion penalty ('TWDP') is decreased in a transmitter. A binary data signal is received for transmission over a channel that exhibits TWDP. The data signal is shifted less than a full clock cycle to generate at least one post cursor signal. The post cursor signal is subtracted from the data signal to generate a transmitter output data signal for transmission over the channel. In addition to decreasing TWDP, data dependent jitter is also reduced for data transmission across a channel that exhibits a multi-pole transmission characteristic. A main data signal and at least one cursor signal, which is shifted at least a portion of a clock period from the main data signal, is generated. The cursor signal is filtered to filter out effects based on the second pole of the multi-pole transmission characteristic. The main data signal is subtracted from the filtered cursor signal to generate the transmitter output data signal. Circuits and methods for transmitting serial data streams over a channel compliant with KR and SPI specifications are also disclosed.

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Burlingame, CA, United States of America

Halil Cirit