A method for determining an inverse impulse response of a communication channel by means of a PAM receiver comprises the following method steps: switching on the PAM receiver; if a second PAM transceiver is switched on, setting a difference between a clock frequency of the data signal and a sampling frequency of the first PAM transceiver; comparing a symbol that is output by the interpreter with a state that is supplied to the interpreter, and outputting an error value, wherein in each case a symbol associated with a sampling clock is compared with a state associated with the same sampling clock; adapting m filter coefficients of the equalizer to minimize error values; repeating the third method step and the fourth method step until an error limit value is reached.

A high-speed signaling system with adaptive transmit pre-emphasis. A transmit circuit has a plurality of output drivers to output a first signal onto a signal path. A receive circuit is coupled to receive the first signal via the signal path and configured to generate an indication of whether the first signal exceeds a threshold level. A first threshold control circuit is coupled to receive the indication from the receive circuit and configured to adjust the threshold level according to whether the first signal exceeds the threshold level. A drive strength control circuit is coupled to receive the indication from the receive circuit and configured to adjust a drive strength of at least one output driver of the plurality of output drivers according to whether the first signal exceeds the threshold level.

A multi-level signal transmitter includes an encoder figured to receive an input data and output a plurality of logical signal sets, each of said plurality of logical signal sets comprising a plurality of logical signals; and a plurality of tree-structured drivers configured to receive said plurality of logical signal sets, respectively, and jointly establish an output voltage at an output node, wherein each of said tree-structure drivers comprises a plurality of inverters configured to receive said plurality of logical signals of its respective logical signal set and jointly establish a joint voltage at a bifurcation node via coupling to the bifurcation node through a plurality of first-level weighting resistors, and a second-level weighting resistor configured to couple the bifurcation node to the output node.

A method for determining an inverse impulse response of a communication channel by means of a PAM receiver comprises the following method steps: switching on the PAM receiver; if a second PAM transceiver is switched on, setting a difference between a clock frequency of the data signal and a sampling frequency of the first PAM transceiver; comparing a symbol that is output by the interpreter with a state that is supplied to the interpreter, and outputting an error value, wherein in each case a symbol associated with a sampling clock is compared with a state associated with the same sampling clock; adapting m filter coefficients of the equalizer to minimize error values; repeating the third method step and the fourth method step until an error limit value is reached.

A memory interface may include a transmitter that generates multi-level signals made up of symbols that convey multiple bits of data. The transmitter may include a first data path for a first bit (e.g., a least significant bit (LSB)) in a symbol and a second data path for a second bit (e.g., the most significant bit (MSB)) in the symbol. Each path may include a de-emphasis or pre-emphasis buffer circuit that inverts and delays signals received at the de-emphasis or pre-emphasis buffer circuit. The delayed and inverted data signals may control de-emphasis or pre-emphasis drivers that are configured to apply de-emphasis or pre-emphasis to a multi-level signal.

A multi-level signal transmitter includes an encoder figured to receive an input data and output a plurality of logical signal sets, each of said plurality of logical signal sets comprising a plurality of logical signals; and a plurality of tree-structured drivers configured to receive said plurality of logical signal sets, respectively, and jointly establish an output voltage at an output node, wherein each of said tree-structure drivers comprises a plurality of inverters configured to receive said plurality of logical signals of its respective logical signal set and jointly establish a joint voltage at a bifurcation node via coupling to the bifurcation node through a plurality of first-level weighting resistors, and a second-level weighting resistor configured to couple the bifurcation node to the output node.

Methods and systems are described for receiving symbols of a codeword via wires of a multi-wire bus, the codeword representing an aggregate sum of a plurality of sub-channel constituent codewords, each sub-channel constituent codeword representing a weight applied to an associated sub-channel vector of a plurality of sub-channel vectors of an orthogonal matrix, generating a plurality of comparator outputs using a plurality of common-mode resistant multi-input comparators (MICs), each common-mode resistant MIC having a set of input coefficients representing a corresponding sub-channel vector of the plurality of sub-channel vectors, each sub-channel vector (i) mutually orthogonal and (ii) orthogonal to a common-mode sub-channel vector, outputting a set of forward-channel output bits formed based on the plurality of comparator outputs, obtaining a sequence of reverse-channel bits, and transmitting the sequence of reverse-channel bits by sequentially transmitting common-mode codewords over the wires of the multi-wire bus.

Methods and systems are described for receiving symbols of a codeword via wires of a multi-wire bus, the codeword representing an aggregate sum of a plurality of sub-channel constituent codewords, each sub-channel constituent codeword representing a weight applied to an associated sub-channel vector of a plurality of sub-channel vectors of an orthogonal matrix, generating a plurality of comparator outputs using a plurality of common-mode resistant multi-input comparators (MICs), each common-mode resistant MIC having a set of input coefficients representing a corresponding sub-channel vector of the plurality of sub-channel vectors, each sub-channel vector (i) mutually orthogonal and (ii) orthogonal to a common-mode sub-channel vector, outputting a set of forward-channel output bits formed based on the plurality of comparator outputs, obtaining a sequence of reverse-channel bits, and transmitting the sequence of reverse-channel bits by sequentially transmitting common-mode codewords over the wires of the multi-wire bus.

An apparatus includes a decision feedback equalizer configured to receive a parallel signal generated based on a first clock. The decision feedback equalizer includes a first equalization block configured to receive a first symbol of a first set of parallel symbols provided by the parallel signal during a first clock cycle of the first clock. A decision feedback equalization is performed by the first equalization block to the first symbol to provide a first decision to a second equalization block. The second equalization block is configured to receive a second symbol of the first set of parallel symbols and perform a decision feedback equalization to the second symbol using the first decision received from the first equalization block to provide a second decision during the first clock cycle.

A high-speed signaling system with adaptive transmit pre-emphasis. A transmit circuit has a plurality of output drivers to output a first signal onto a signal path. A receive circuit is coupled to receive the first signal via the signal path and configured to generate an indication of whether the first signal exceeds a threshold level. A first threshold control circuit is coupled to receive the indication from the receive circuit and configured to adjust the threshold level according to whether the first signal exceeds the threshold level. A drive strength control circuit is coupled to receive the indication from the receive circuit and configured to adjust a drive strength of at least one output driver of the plurality of output drivers according to whether the first signal exceeds the threshold level.