Abstract: A system and method for efficiently generating clock signals are described. In various implementations, an integrated circuit includes multiple clock frequency dividers both at its I/O boundaries and across its die. A clock frequency divider utilizes a first clock divider and a second clock divider that receive input clock signals with an initial phase difference between them. The first clock divider and the second clock divider generate output clock signals that have frequencies that are a fraction of the frequencies of the received input clock signals. The second clock divider uses a combined multiplexer and flip-flop (combined mux-flop) circuit. The combined mux-flop circuit receives a reset signal that is asserted asynchronously with respect to an input clock signal received by the second clock divider. The second clock divider generates an output clock signal that has the initial phase difference with an output clock signal of the first clock divider.

Abstract: Systems, apparatuses, and methods for utilizing training sequences on a replica lane are described. A transmitter is coupled to a receiver via a communication channel with a plurality of lanes. One of the lanes is a replica lane used for tracking the drift in the optimal sampling point due to temperature variations, power supply variations, or other factors. While data is sent on the data lanes, test patterns are sent on the replica lane to determine if the optimal sampling point for the replica lane has drifted since a previous test. If the optimal sampling point has drifted for the replica lane, adjustments are made to the sampling point of the replica lane and to the sampling points of the data lanes.

Abstract: Systems, apparatuses, and methods for performing efficient data transfer in a computing system are disclosed. A computing system includes multiple transmitters sending singled-ended data signals to multiple receivers. In order to better handle noise issues when using single-ended signaling, one or more of the receivers include equalization circuitry and termination circuitry. The termination circuitry prevents reflection on a corresponding transmission line ending at a corresponding receiver. The equalization circuitry uses a bridged T-coil circuit to provide continuous time linear equalization (CTLE) with no feedback loop. The equalization circuitry performs equalization by providing a high-pass filter that offsets the low-pass characteristics of a corresponding transmission line. A comparator of the receiver receives the input signal and compares it to a reference voltage.

Abstract: Systems, apparatuses, and methods for implementing a periodic receiver clock data recovery scheme with dynamic data edge paths are disclosed. An IQ link calibration scheme performs a non-destructive data and edge path switch to determine an IQ offset without disturbing the data. A data path and an edge path pass through multiple stages of deserializers to widen the data path, with the deserializers clocked by clock divided versions of the original data and edge clocks. To initiate a calibration routine, the edge clock is aligned with the data clock, and then data and edge paths are swapped at a common point in a slower clock domain. The data path is then calibrated while the edge path carries the data signal. After the data path is calibrated, the edge and data paths are swapped back to the original configuration.

Abstract: Systems, apparatuses, and methods for implementing a combo scheme for direct current (DC) level shifting of signals are disclosed. A receiver circuit receives an input signal on a first interface. The first interface is coupled to a resistor in parallel with a capacitor which passes the input signal to a second interface. Also, the first interface is coupled to a first pair of current sources between ground and a voltage source, and the second interface is coupled to a second pair of current sources between ground and the voltage source. An op-amp drives the current sources based on a difference between a sensed common mode voltage and a reference voltage. Based on this circuit configuration, the receiver circuit is able to prevent baseline wander, perform a DC level shift of the input signal, and achieve linear equalization of the input signal.

Abstract: A system and method for efficiently generating clock signals are described. In various implementations, an integrated circuit includes multiple clock frequency dividers both at its I/O boundaries and across its die. A clock frequency divider utilizes a first clock divider and a second clock divider that receive input clock signals with an initial phase difference between them. The first clock divider and the second clock divider generate output clock signals that have frequencies that are a fraction of the frequencies of the received input clock signals. The second clock divider uses a combined multiplexer and flip-flop (combined mux-flop) circuit. The combined mux-flop circuit receives a reset signal that is asserted asynchronously with respect to an input clock signal received by the second clock divider. The second clock divider generates an output clock signal that has the initial phase difference with an output clock signal of the first clock divider.

Abstract: Systems, apparatuses, and methods for utilizing training sequences on a replica lane are described. A transmitter is coupled to a receiver via a communication channel with a plurality of lanes. One of the lanes is a replica lane used for tracking the drift in the optimal sampling point due to temperature variations, power supply variations, or other factors. While data is sent on the data lanes, test patterns are sent on the replica lane to determine if the optimal sampling point for the replica lane has drifted since a previous test. If the optimal sampling point has drifted for the replica lane, adjustments are made to the sampling point of the replica lane and to the sampling points of the data lanes.

Abstract: Systems, apparatuses, and methods for utilizing training sequences on a replica lane are described. A transmitter is coupled to a receiver via a communication channel with a plurality of lanes. One of the lanes is a replica lane used for tracking the drift in the optimal sampling point due to temperature variations, power supply variations, or other factors. While data is sent on the data lanes, test patterns are sent on the replica lane to determine if the optimal sampling point for the replica lane has drifted since a previous test. If the optimal sampling point has drifted for the replica lane, adjustments are made to the sampling point of the replica lane and to the sampling points of the data lanes.

Abstract: Systems, apparatuses, and methods for performing efficient data transfer in a computing system are disclosed. A termination voltage generator includes an inverter-based chopper circuit, which uses a first group of an even number of serially connected inverters coupled between the output node of the chopper circuit and the gate terminal of an output pmos transistor. Additionally, a second group of an even number of serially connected inverters is coupled between the output node and the gate terminal of an output nmos transistor. A replica inverter includes two serially connected pmos transistors and two serially connected nmos transistors. Each of one pmos transistor and one nmos transistor receives a generated voltage set as the expected value of the termination voltage. Each of the other pmos transistor and nmos transistor receives an output based on a comparison between the expected value to the output of the replica inverter.

Abstract: Systems, apparatuses, and methods for performing efficient data transfer in a computing system are disclosed. A termination voltage generator includes an inverter-based chopper circuit, which uses a first group of an even number of serially connected inverters coupled between the output node of the chopper circuit and the gate terminal of an output pmos transistor. Additionally, a second group of an even number of serially connected inverters is coupled between the output node and the gate terminal of an output nmos transistor. A replica inverter includes two serially connected pmos transistors and two serially connected nmos transistors. Each of one pmos transistor and one nmos transistor receives a generated voltage set as the expected value of the termination voltage. Each of the other pmos transistor and nmos transistor receives an output based on a comparison between the expected value to the output of the replica inverter.

Abstract: Systems, apparatuses, and methods for implementing asynchronous feedback training sequences are described. A transmitter transmits a training sequence indication to a receiver via a communication channel including a plurality of data lines. The training sequence indication includes a bit sequence to indicate the beginning of a training sequence. The indication includes a transition from a zero to a one at the midpoint of a supercycle of ‘N’ clock cycles in length, followed by a predetermined number of ones. The training sequence indication is then followed by a test pattern. The beginning of the test pattern occurs at the end of a supercycle. The receiver determines if there are any errors in the received test pattern, and then sends feedback to the transmitter that indicates whether any errors were detected. Responsive to receiving the feedback, the transmitter alters delay settings for one or more of the data lines.

Abstract: Systems, apparatuses, and methods for utilizing training sequences on a replica lane are described. A transmitter is coupled to a receiver via a communication channel with a plurality of lanes. One of the lanes is a replica lane used for tracking the drift in the optimal sampling point due to temperature variations, power supply variations, or other factors. While data is sent on the data lanes, test patterns are sent on the replica lane to determine if the optimal sampling point for the replica lane has drifted since a previous test. If the optimal sampling point has drifted for the replica lane, adjustments are made to the sampling point of the replica lane and to the sampling points of the data lanes.

Abstract: Systems, apparatuses, and methods for implementing asynchronous feedback training sequences are described. A transmitter transmits a training sequence indication to a receiver via a communication channel including a plurality of data lines. The training sequence indication includes a bit sequence to indicate the beginning of a training sequence. The indication includes a transition from a zero to a one at the midpoint of a supercycle of ‘N’ clock cycles in length, followed by a predetermined number of ones. The training sequence indication is then followed by a test pattern. The beginning of the test pattern occurs at the end of a supercycle. The receiver determines if there are any errors in the received test pattern, and then sends feedback to the transmitter that indicates whether any errors were detected. Responsive to receiving the feedback, the transmitter alters delay settings for one or more of the data lines.

Abstract: Systems, apparatuses, and methods for performing common mode extraction for data communication are disclosed. A circuit is configured to receive a single-ended data signal on a first input port and couple the data signal to a positive input terminal of a receiver component. The circuit is also configured to receive a differential clock signal on second and third input ports and generate a reference signal from the differential clock signal. In one embodiment, the reference signal is generated from an average of the differential clock signal. The circuit is configured to couple the reference signal to a negative input terminal of the receiver component. In one embodiment, the receiver component is an amplifier.

Abstract: A controller integrated in a memory physical layer interface (PHY) can be used to control training used to configure the memory PHY for communication with an associated external memory such as a dynamic random access memory (DRAM), thereby removing the need to provide training sequences over a data pipeline between a BIOS and the memory PHY. For example, a controller integrated in the memory PHY can control read training and write training of the memory PHY for communication with the external memory based on a training algorithm. The training algorithm may be a seedless training algorithm that converges on a solution for a timing delay and a voltage offset between the memory PHY and the external memory without receiving, from a basic input/output system (BIOS), seed information that characterizes a signal path traversed by training sequences or commands generated by the training algorithm.

Abstract: A controller integrated in a memory physical layer interface (PHY) can be used to control training used to configure the memory PHY for communication with an associated external memory such as a dynamic random access memory (DRAM), thereby removing the need to provide training sequences over a data pipeline between a BIOS and the memory PHY. For example, a controller integrated in the memory PHY can control read training and write training of the memory PHY for communication with the external memory based on a training algorithm. The training algorithm may be a seedless training algorithm that converges on a solution for a timing delay and a voltage offset between the memory PHY and the external memory without receiving, from a basic input/output system (BIOS), seed information that characterizes a signal path traversed by training sequences or commands generated by the training algorithm.

Abstract: A method is provided for sampling a data strobe signal of a memory cycle and determining a receiver enable phase based upon the data strobe signal. The method also includes performing a memory write cycle and a subsequent read cycle and training a read data strobe cycle at a one-quarter memory clock periodic offset. The method also includes determining a correct receiver enable delay in response to a successful read data strobe training cycle. Computer readable storage media are also provided. An apparatus is provided that includes a communication interface portion that is coupled to a memory portion and to a processing device. The apparatus also includes a first circuit portion, coupled to the communication interface portion. The first circuit portion monitors memory cycles on the communication interface portion, determines a receiver enable cycle phase and train a receiver enable cycle without using receiver enable seed.

Abstract: In one form, a memory module includes a first plurality of memory devices comprising a first rank and having a first group and a second group, and first and second chip select conductors. The first chip select conductor interconnects chip select input terminals of each memory device of the first group, and the second chip select conductor interconnects chip select input terminals of each memory device of the second group. In another form, a system includes a memory controller that performs a first burst access using both first and second portions of a data bus and first and second chip select signals in response to a first access request, and a second burst access using a selected one of the first and second portions of the data bus and a corresponding one of the first and second chip select signals in response to a second access request.

Abstract: A system and method of data communications between a first device and a second device is disclosed. The method includes generating a first clock signal at the first device and generating a second clock signal having a phase offset from the first clock signal. The clock signals are transmitted from the first device to the second device. The method further includes regulating transmission of a read strobe signal sent from the second device to the first device utilizing the first clock signal. The method also includes regulating transmission of a data transfer signal sent from the second device to the first device utilizing the second clock signal.

Abstract: Various method and apparatus embodiments for training a delay for enabling a data strobe signal in a memory subsystem are disclosed. In one embodiment, a system includes a memory controller configured to receive a data strobe signal. The memory controller includes a training circuit. The training circuit includes a first storage circuit coupled to receive the data strobe signal on a data input and an enable signal on a clock input, and a training unit configured to, based on an output signal received from the first flip-flop, adjust a phase of the enable signal until an assertion of the enable signal coincides with a preamble indication in the data strobe signal.