International Business Machines Corporation

Christian I Menolfi

Thomas Helmut Toifl

Martin L Schmatz

Alessandro Cevrero

Ilter Özkaya

Marcel A Kossel

Pier Andrea Francese

Christoph Hermann Hagleitner

Thomas E Morf

Michael V Koch

Matthias Ringe

Daniel Michael Kuchta

Fatih Cilek

Guenther Hutzl

Marc Seifried

Dieter Nissler

Hayden C Cranford, Jr

Pradeep Thiagarajan

Andreas Arp

Daihyun Lim

Juergen Hertle

A system and method for a high-speed transmitter comprising a precoder configured to receive a sequence of input symbols and to generate for each received symbol a respective recoded symbol is disclosed. The transmitter includes a recoding unit configured for recoding each current received PAM-M based on the recoded symbol immediately preceding the current recoded symbol at the recoding unit, a shift unit configured for determining a shift value for each current received symbol from the recoding unit based on the symbol received from the recoding unit and immediately preceding the current symbol at the shift unit; and Feed-Forward Equalizer unit for applying the shift values to the respective symbols received from the recoding unit to generate a corresponding sequence of output symbols to be transmitted in an output stream.

PAM-4 transmitter precoder for 1+0.5D PR channels

Devices and methods are provided to reduce the wake-up time of a Vertical Cavity Surface Emitting Laser (VCSEL) used in a data communication link. For example, in one aspect, a method for optical communications includes, in an optical communication device including a light-emitting device, applying a bias current to the light-emitting device and transmitting a pulse to the light-emitting device before transmitting a preamble signal or data signal to the light-emitting device, wherein the pulse has a voltage greater than a highest voltage of the preamble signal or data signal.

VCSEL based optical links in burst mode

A method, apparatus, and computer program product for measuring a slew rate of a digital high speed repeating signal on-chip including, transforming the rising and the falling edges of the signal into a digital pulse signal each; and selecting the digital pulse signals corresponding either to the rising edge or to the falling edge of the signal. Further the method including converting the selected digital pulse signals into an average DC voltage equivalent to the pulse width of the respective digital pulse signal; as well as converting each DC voltage into a binary value.

Measuring a slew rate on-chip

The present disclosure regards adjusting a duty cycle, which includes generating a duty cycle signal having a voltage representing a duty cycle of a clock signal; adjusting a reference voltage generated by an adjustable reference voltage generator to match the duty cycle signal to produce a first matched value; inverting voltage sources of the reference voltage generator; adjusting, while the voltage sources are inverted, the reference voltage to produce a second matched value; and calculating a duty cycle value based on the first and second matched values.

Duty cycle adjustment with error resiliency

A decision feedback equalizer (DFE) slice for a receiver includes a plurality of non-speculative DFE taps; and 3 speculative DFE taps, wherein the 3 speculative DFE taps comprise first and second multiplexer stages, each of the first and second multiplexer stages including 4 comparator latches, each of the 4 comparator latches having a programmable offset; and a multiplexer that receives 4 comparator latch outputs from the 4 comparator latches and outputs a multiplexer stage output, wherein the multiplexer is controlled by previous symbol decisions dand d; and wherein the 3 speculative taps further comprise a 2:1 decision multiplexer stage that receives the multiplexer stage outputs of the first and second multiplexer stages and is controlled by a previous symbol decision dto output a slice output signal d.

Receiver with four-slice decision feedback equalizer

An inverter-type high speed driver circuit having a first inverter branch and a second inverter branch wherein each of the inverter branches comprising a parallel circuit of a serial connection of a first impedance tuning unit and a respective first clocking transistor and a serial connection of a second impedance tuning unit and a respective second clocking transistor. The impedance tuning units are configured to adapt the conductivity of the respective inverter branch to set the output impedance of the driver circuit and each of the impedance tuning units is controlled in accordance with a data stream.

High-speed driver circuit

A duty cycle adjustment circuit includes a clock signal input node; a clock signal output node; a control voltage generation circuit coupled to the clock signal input node; and a first inverter configured to receive an inverter input signal comprising a sum of an input clock signal received at the clock signal input node and a control voltage received from the control voltage generation circuit, and to output an output clock signal at the clock signal output node, wherein variation of the control voltage is configured to vary a duty cycle of the output clock signal.

Duty cycle adjustment circuit

A method for startup and operation of an output stage of a transmitter, the output stage comprising a first protection field effect transistor (FET) and a second protection FET includes enabling a startup circuit; providing a first bias voltage to the first protection FET in the output stage and a second bias voltage to the second protection FET stage in the output stage by the startup circuit; disabling the startup circuit and enabling a protection voltage generator; providing the first bias voltage to the first protection FET in the output stage by the protection voltage generator; and providing the second bias voltage to the second protection FET in the output stage by a second bias voltage power supply.

Startup and protection circuitry for thin oxide output stage

The communication system having a transmitter and a receiver, wherein the transmitter and the receiver are coupled by a clock channel and a data channel, wherein the clock channel is shorter than the data channel and wherein the receiver comprises a delay circuit for extracting a jitter signal from a clock channel signal, delaying the extracted jitter signal, and generating a receiver clock signal for the receiver by the delayed jitter signal.

Low jitter communication system

A high-speed receiver includes multiple receiver components. Each receiver component includes sampling latches for receiving data, phase rotators for controlling timing of sampling of data by the sampling latches, and a clock-tracking logic stage for providing clock and data recovery. The clock-tracking logic stage is divided into a high-speed early/late (E/L) logic and aggregation counter section and a low-speed logic section, separated by a synchronization logic block. The receiver also includes a delay locked loop (DLL) for receiving an input clock signal corresponding to a data rate of the received data, providing coarse delay adjustment of the clock signal and outputting multiple clock phase vectors corresponding to the adjusted clock signal to the phase rotators on each receiver component. The phase rotators control sampling of the data based on the clock phase vectors received from the DLL. A single regulated power supply regulator regulates power supplied to the DLL and the phase rotators.

Low-power, low-area high-speed receiver architecture

The phase locked loop (PLL) with adjustable phase shift is described. The PLL includes a voltage controlled oscillator which is capable of generating multiple phase shifted output signals, and multiple phase detectors capable of determining the phase differences between the output signals and a reference clock. The PLL further includes a weighting device capable of weighting the phase differences and generating a control signal for the voltage controlled oscillator.

Phase locked loop apparatus with adjustable phase shift

A driver circuit is provided comprising at least two equal main units (MU) each comprising at least two sub units (SU) coupled to a data output (dout). Each sub unit (SU) is adapted to represent a respective predetermined impedance. Each main unit (MU) is adapted to that, when in a data mode, each sub unit (SU) of the respective main unit (MU) is switchable to either a first or second reference potential depending on a data signal to transmit. Each main unit (MU) is further adapted to that, when in a termination mode, the sub units (SU) of the respective main unit (MU) are switched to either the first or second reference potential such that an output of the respective main unit (MU) is neutral with respect to the driving of the data output (dout) to the first or second reference potential.

Driver circuit

A signal generator for generating multiple phases includes a ring oscillator with at least one first adjustable delay stage and at least one second delay stage being serially arranged, wherein an output of the first delay stage is provided for delivering at least one first output phase and an output of the second delay stage is provided for delivering at least one second output phase, and an adjustment circuit for adjusting the delay of the first adjustable delay stage, wherein the adjustment circuit is provided for adjusting the phase relationship between the first output phase and the second output phase by means of setting a first propagation delay for the first delay stage.

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Langnau am Albis, Switzerland

Christian I Menolfi