摘要:
A method and a system for providing ISI compensation to an input signal in a bifurcated manner. ISI compensation is provided in two stages, a first stage compensates ISI components induced by characteristics of a transmitter's partial response pulse shaping filter, a second stage compensates ISI components induced by characteristics of a multi-pair transmission channel. First stage ISI compensation is performed in an inverse response filter having a characteristic feedback gain factor K, during system start-up. Second stage ISI compensation is performed by a single DFE in combination with a MDFE operating on tentative decisions output from a Viterbi decoder. As the DFE of the second stage reaches convergence, the feedback gain factor K of the first stage is ramped to zero.
摘要:
A method and a system for decoding information signals encoded in accordance with a multi-state encoding scheme and transmitted over a multi-dimensional transmission channel by computing a distance of a received word from a codeword. One-dimensional (1D) input signals are processed in a pair of symbol decoders, implemented as look-up tables, to produce a pair of 1D errors, with each representing a distance metric between the input signal and a symbol in one of two disjoint symbol-subsets. The 1D errors are combined based on the multi-state encoding scheme in order to produce a set of multi-dimensional error terms. Each of the multi-dimensional error terms corresponds to a distance between a received word and a nearest codeword.
摘要:
A method and a system for providing ISI compensation to an input signal in a bifurcated manner. ISI compensation is provided in two stages, a first stage compensates ISI components induced by characteristics of a transmitter's partial response pulse shaping filter, a second stage compensates ISI components induced by characteristics of a multi-pair transmission channel. First stage ISI compensation is performed in an inverse response filter having a characteristic feedback gain factor K, during system start-up. Second stage ISI compensation is performed by a single DFE in combination with a MDFE operating on tentative decisions output from a Viterbi decoder. As the DFE of the second stage reaches convergence, the feedback gain factor K of the first stage is ramped to zero.
摘要:
A method and a system for providing ISI compensation to an input signal in a bifurcated manner. ISI compensation is provided in two stages, a first stage compensates ISI components induced by characteristics of a transmitter's partial response pulse shaping filter, a second stage compensates ISI components induced by characteristics of a multi-pair transmission channel. First stage ISI compensation is performed in an inverse response filter having a characteristic feedback gain factor K, during system start-up. Second stage ISI compensation is performed by a single DFE in combination with a MDFE operating on tentative decisions output from a Viterbi decoder. As the DFE of the second stage reaches convergence, the feedback gain factor K of the first stage is ramped to zero.
摘要:
A method and a system for decoding information signals encoded by a multi-state encoding architecture and transmitted over a multi-dimensional transmission channel by computing a distance of a received word from a codeword. One-dimensional (1D) input signals are detected in a symbol decoder, implemented using look-up tables, to produce a pair of 1D errors, with each representing a distance metric between the input signal and a symbol in one of two disjoint symbol-subsets. The symbol decoder is implemented as a pair of slicers, each detecting an input signal with respect to one of two disjoint symbol-subsets. A third slicer detects the input with respect to the union of the two disjoint symbol-subsets. Decisions from the first, second and third slicers are processed to define 1D square error terms expressed in Hamming metrics. Reduced bit count error terms allow follow-on error processing to be performed with a minimum of computational complexity. The 1D errors are combined to produce a set of multi-dimensional error terms. Each of the multi-dimensional error terms corresponds to a distance between a received word and a nearest codeword.
摘要:
A feedforward equalizer for equalizing a sequence of signal samples received by a receiver from a remote transmitter. The feedforward equalizer has a gain and is included in the receiver which includes a timing recovery module for setting a sampling phase and a decoder. The feedforward equalizer comprises a non-adaptive filter and a gain stage. The non-adaptive filter receives the signal samples and produces a filtered signal. The gain stage adjusts the gain of the feedforward equalizer by adjusting the amplitude of the filtered signal. The amplitude of the filtered signal is adjusted so that it fits in the operational range of the decoder. The feedforward equalizer does not affect the sampling phase setting of the timing recovery module of the receiver.
摘要:
A method and a system for decoding information signals encoded in accordance with a multi-state encoding scheme and transmitted over a multi-dimensional transmission channel by computing a distance of a received word from a codeword. One-dimensional (1D) input signals are processed in a pair of symbol decoders, implemented as look-up tables, to produce a pair of 1D errors, with each representing a distance metric between the input signal and a symbol in one of two disjoint symbol-subsets. The 1D errors are combined based on the multi-state encoding scheme in order to produce a set of multi-dimensional error terms. Each of the multi-dimensional error terms corresponds to a distance between a received word and a nearest codeword.
摘要:
Various systems and methods providing high speed decoding, enhanced power reduction and clock domain partitioning for a multi-pair gigabit Ethernet transceiver are disclosed. ISI compensation is partitioned into two stages; a first stage compensates ISI components induced by characteristics of a transmitter's partial response pulse shaping filter in a demodulator, a second stage compensates ISI components induced by characteristics of a multi-pair transmission channel in a Viterbi decoder. High speed decoding is accomplished by reducing the DFE depth by providing an input signal from a multiple decision feedback equalizer to the Viterbi based on a tail value and a subset of coefficient values received from a unit depth decision-feedback equalizer. Power reduction is accomplished by adaptively truncating active taps in the NEXT, FEXT and echo cancellation filters, or by disabling decoder circuitry portions, as channel response characteristics allow. A receive clock signal is generated such that it is synchronous in frequency with analog sampling clock signals and has a particular phase offset with respect to one of the sampling clock signals. This phase offset is adjusted such that system performance degradation due to coupling of switching noise from the digital sections to the analog sections is substantially minimized.
摘要:
Various systems and methods providing high speed decoding, enhanced power reduction and clock domain partitioning for a multi-pair gigabit Ethernet transceiver are disclosed. ISI compensation is partitioned into two stages; a first stage compensates ISI components induced by characteristics of a transmitter's partial response pulse shaping filter in a demodulator, a second stage compensates ISI components induced by characteristics of a multi-pair transmission channel in a Viterbi decoder. High speed decoding is accomplished by reducing the DFE depth by providing an input signal from a multiple decision feedback equalizer to the Viterbi based on a tail value and a subset of coefficient values received from a unit depth decision-feedback equalizer. Power reduction is accomplished by adaptively truncating active taps in the NEXT, FEXT and echo cancellation filters, or by disabling decoder circuitry portions, as channel response characteristics allow. A receive clock signal is generated such that it is synchronous in frequency with analog sampling clock signals and has a particular phase offset with respect to one of the sampling clock signals. This phase offset is adjusted such that system performance degradation due to coupling of switching noise from the digital sections to the analog sections is substantially minimized.
摘要:
Circuitry to remove switches from signal paths in integrated circuit programmable gain attenuators Programmable gain attenuators and programmable gain amplifiers commonly switch between signal levels using semi-conductor switches. Such switches may introduce non-linearities in the signal, By isolating the switches from the signal path linearity of the PGA can be improved.