Abstract:
A mechanism is provided for constructing an oversampled waveform for a set of incoming signals received by a receiver. In one implementation, the oversampled waveform is constructed by way of cooperation between the receiver and a waveform construction mechanism (WCM). The receiver receives the incoming signals, samples a subset of the incoming signals at a time, stores the subsets of sample values into a set of registers, and subsequently provides the subsets of sample values to the WCM. The WCM in turn sorts through the subsets of sample values, organizes them into proper orders, and “stitches” them together to construct the oversampled waveform for the set of incoming signals. With proper cooperation between the receiver and the WCM, and with proper processing logic on the WCM, it is possible to construct the oversampled waveform for the incoming signals without requiring large amounts of resources on the receiver.
Abstract:
A receiver circuit is described. In the receiver circuit, an analog-to-digital converter (ADC) generates first samples of a data signal based on a first clock signal, and a clock-data-recovery (CDR) error-detection circuit generates second samples of the data signal based on a second clock signal. In addition, the CDR error-detection circuit estimates intersymbol interference (ISI) at a current sample in the second samples from an adjacent, subsequent sample in the second samples. Based on the second samples and the estimated ISI, a CDR circuit generates the first clock signal and the second clock signal, which involves modifying the skews of either or both of these clock signals so that the current sample is associated with a zero crossing of a pulse response of a communication channel from which the data signal was received, thereby reducing or eliminating the ISI from the adjacent, subsequent sample.
Abstract:
A system and methods for recovering data from an input data signal are disclosed. The system includes a transmitter for conveying a data signal filtered by a finite impulse response (FIR) filter to a receiver via a channel. The receiver uses an adaptive algorithm to determine update signals for a pre-cursor tap coefficient of the FIR based on samples taken from the received data signal and conveys the update signals to the FIR. To generate update signals, the receiver samples the data signal at a phase estimated to correspond to a peak amplitude of a pulse response of the channel. The phase is based on a clock recovered from the data signal. The update signals increase or decrease a pre-cursor tap coefficient setting in response to determining that the phase corresponds to a point earlier or later, respectively, than the peak amplitude of the channel's pulse response.
Abstract:
A two stage fully differential amplifier has been designed which works, in tandem with a TX-FIR, as a linear equalizer at low frequencies, not covered by the TX-FIR, and also acts as a linear amplifier at higher frequencies which are equalized by the TX-FIR. The amplifier as a frequency response which does not attenuate signals frequencies less than one twentieth of baud rate, creates gain peaking ion the region between one twentieth and one tenth of baud rate and maintains flat peak gain up to half of baud rate. Different aspects of the frequency response curve (such as dc gain, max gain and zero frequency) are completely programmable. Also, the differential amplifier has been designed from low power and process, voltage and temperature insensitive frequency response.
Abstract:
The present invention discloses a system and method for channel coding data within a digital communication system. A data receiving circuit receives a digital input data sequence and periodically inserts known symbols, such as zeros, into the digital input data sequence as part of a convolutional zero code of the present invention. It forms an expanded digital input data sequence. An encoder is operatively connected to the data receiving circuit and trellis encodes the expanded sequence to produce a channel coded data stream such that the number of connections between trellis nodes in a trellis are reduced.
Abstract:
In a receiver circuit, a node receives a signal that carries data from a transmitter circuit. Moreover, a clock-data-recovery (CDR) circuit in the receiver circuit recovers an at-rate clock signal from the received signal. The CDR circuit recovers the clock signal without converging a first pulse-response precursor of the signal relative to a pulse-response cursor of the signal to approximately zero (e.g., with the first pulse-response precursor h(−1) converged to a non-zero value). Furthermore, the first pulse-response precursor corresponds to at least one precurosor or postcursor of the pulse-response other than the current sample.
Abstract:
A receiver circuit includes a first slicer coupled to receive data signals from a signal path and a reference voltage from a reference voltage path that is separate from the signal path. The first slicer is configured output a logic value based on a comparison between a voltage of the data signal and the reference voltage. The receiver circuit further includes a reference voltage generator configured to generate the reference voltage. The reference voltage generator is configured to dynamically generate the reference voltage based on logic values of previously received signals during operation in a first mode. During operation in a second mode, the reference voltage generator is configured to generate and provide the reference voltage as a static voltage.
Abstract:
A receiver circuit includes a first slicer coupled to receive data signals from a signal path and a reference voltage from a reference voltage path that is separate from the signal path. The first slicer is configured output a logic value based on a comparison between a voltage of the data signal and the reference voltage. The receiver circuit further includes a reference voltage generator configured to generate the reference voltage. The reference voltage generator is configured to dynamically generate the reference voltage based on logic values of previously received signals during operation in a first mode. During operation in a second mode, the reference voltage generator is configured to generate and provide the reference voltage as a static voltage.
Abstract:
A system and method include a SerDes transmitter comprising a digital block operating in a digital voltage domain. The digital block can be configured to receive a first group of bits of data in parallel and store history bits from another group of data. The SerDes transmitter can further comprise an analog block operating in an analog voltage domain. The analog block can be configured to receive the first group of bits of data from the digital block, receive the history bits from the digital block, generate a plurality of combinations of bits with one or more bits from the first group of bits and zero or more bits from the history bits, align each combination of bits to a phase of a multi-phase clock; and input each combination into an output driver.
Abstract:
A feedback module is defined to receive as input a set of data sample signals and a set of reference sample signals. Each of the data and reference sample signals is generated by sampling a differential signal having been transmitted through a FIR filter. The feedback module is defined to operate a respective post cursor counter for each post cursor of the FIR filter and update the post cursor counters based on the received sets of data and reference sample signals. Also, the feedback module is defined to generate a tap weight adjustment signal for a given tap weight of the FIR filter when a magnitude of a post cursor counter corresponding to the given tap weight is greater than or equal to a threshold value. An adaptation module is defined to adapt a reference voltage used to generate the reference sample signals to a condition of the differential signal.