A multi-carrier data communications system and method having high spectral efficiency. The method includes encoding input digital data at selected phase angles of a plurality of sinusoidal waveforms to create a plurality of modulated sinusoidal waveforms. An output analog waveform is generated where the output analog waveform includes a plurality of encoded analog communication signals corresponding to a plurality of digital representations of the plurality of modulated sinusoidal waveforms. The encoding is performed so that adjacent ones of the plurality of modulated sinusoidal waveforms are separated in frequency by less than 15 Hz and any sideband included within the output analog waveform is of a power at least 50 dB below a power of the encoded analog communication signal associated with the sideband.

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.

Techniques are provided herein to increase a rate of data transfer across a large number of channels in a memory device using multi-level signaling. Such multi-level signaling may be configured to increase a data transfer rate without increasing the frequency of data transfer and/or a transmit power of the communicated data. An example of multi-level signaling scheme may be pulse amplitude modulation (PAM). Each unique symbol of the multi-level signal may be configured to represent a plurality of bits of data.

An encoding modulation method and transmitter are described. The method includes: oversampling and noise-shaping received multi-bit data to obtain N bits of data; using the N bits of data as a lookup table address to obtain a PWM puke modulation signal; multiplexing synthetic orthogonal (IQ) complex data of the PWM pulse modulation signal to be real number signal data; and converting the multiplexed real number signal data to an analog signal for power amplification and output, N being an integer representing a smaller number of bits than the received multi-bit data.

An optical communication transmitter includes a modulation circuit and a vertical cavity surface emitting laser (VCSEL) transmission module, The modulation circuit is used for performing a four-level pulse amplitude modulation (PAM4) on the input data in order to generate a modulation signal. The VCSEL transmission module is coupled to the modulation circuit and uses an injection lock technique to generate and transmit an output optical signal based on the modulation signal.

The present invention discloses a signal modulation method, including: demultiplexing an input signal into 2N sub-signals; grouping every two of the 2N sub-signals into a pair; performing filtering on two sub-signals in each pair; performing carrierless amplitude phase (CAP) modulation on the two sub-signals in each pair; modulating the two sub-signals in each pair to a same frequency band, to generate N pairs of CAP signals, where frequency bands of different pairs of sub-signals are different, and a spacing between center frequencies of two neighboring frequency bands is greater than or equal to an average value of baud rates of sub-signals corresponding to the two neighboring frequency bands; and combining the N pairs of CAP signals, and performing electro-optic modulation on a signal obtained after the combining. A signal demodulation method corresponding to the signal modulation method is further disclosed.

A technical solution is directed to a clock recovery apparatus for multi-level signaling on a single-lane communication interface. The apparatus can use bin-map logic to successfully recover a common clock per symbol received on the multi-level signal interface. The multi-level signal can be PAM4 signaling where two bits are encoded to represent four levels. The clock recovery apparatus can detect signal level through individual edge detectors for each of the two bits and can handle jitter up to half-clock period.

Techniques are provided herein to increase a rate of data transfer across a large number of channels in a memory device using multi-level signaling. Such multi-level signaling may be configured to increase a data transfer rate without increasing the frequency of data transfer and/or a transmit power of the communicated data. An example of multi-level signaling scheme may be pulse amplitude modulation (PAM). Each unique symbol of the multi-level signal may be configured to represent a plurality of bits of data.

A modulating system (14) adapted to generate a multi-level quadrature amplitude modulation, includes: a first number of first optical channels (24_1), each of the first optical channels (24_1) including a modulating device (28), and a second number of first optical channels (24_1) each including a first phase shifting unit capable of introducing a phase shift of , and a first number of second optical channels (24_2), each of the second optical channels (24_2) being associated bijectively with one of the first optical channels (24_1), each of the second optical channels (24_2) including the same elements as the first optical channel (24_1) with which the second optical channel (24_2) is associated and a second phase shifting unit able to introduce a phase shift of /2.

A processor can be configured to execute instructions stored in the memory to position a first point in a grid space that represents an unmodulated signal component of a first signal based on a characteristic of a frequency modulator generating the first signal. The frequency modulator can include a first input to receive data from a baseband source and can include a second input to receive a second signal from a local oscillator. The processor can determine, in the grid space, a first angle between a first line segment from a reference point to the first point and a second line segment from the first point to a point representing the first offset signal applied to the frequency modulator. The processor can additionally apply a second offset signal, based on the first angle, to compensate for the characteristic of the frequency modulator.