Abstract: In some embodiments, the invention involves a system having a first group of integrated circuits connected in a truncated ring fashion, wherein the truncated ring includes a truncated region to allow for additional integrated circuits to be added to the ring. In some embodiments, the invention involves a system having a group of integrated circuits connected in a pseudo ring fashion, wherein the pseudo ring is created by data flow of bi-directional signaling between the integrated circuits. In some embodiments, the invention involves a system having a group of integrated circuits connected in a pseudo differential arrangement in which multiple conductors carrying signals share a common reference signal conductor.

Abstract: A current summing FIR filter can be implemented with multiple differential input stages and variable tail currents. The variable tail currents can be used to appropriately weight the present and previous digital input signals. The weighted outputs of the differential transistor pairs can be summed to provide a filtered output signal. The tail currents can be advantageously varied with variable current sources or by adjustment of the relative widths of the differential transistor pairs. In other embodiments, additional differential pairs can be added to adjust for systematic offset voltages caused by process-induced variations in the structure of circuit devices or to induce a desired offset.

Abstract: A simultaneous bidirectional port coupled to a bus combines a synchronization circuit and a clock circuit. The synchronization and clock circuit synchronizes the port with another simultaneous data port coupled to the same bus. A clock driver circuit is provided that is capable of being turned on and off. Prior to synchronization, the clock driver is off, and after synchronization, the clock driver is on. A clock receiver circuit includes a clock detection circuit to detect the presence of an input clock signal. When an integrated circuit is ready to communicate, the output clock driver is turned on and the clock detection circuit is monitored to determine when an input clock signal is received. When both the output clock driver is turned on, and an input clock signal is being received, the simultaneous bidirectional port is synchronized, and communication between integrated circuits can take place.

Abstract: A simultaneous bidirectional port coupled to a bus combines a synchronization circuit and a clock circuit. The synchronization and clock circuit synchronizes the port with another simultaneous data port coupled to the same bus. A clock driver circuit is provided that is capable of being turned on and off. Prior to synchronization, the clock driver is off, and after synchronization, the clock driver is on. A clock receiver circuit includes a clock detection circuit to detect the presence of an input clock signal. When an integrated circuit is ready to communicate, the output clock driver is turned on and the clock detection circuit is monitored to determine when an input clock signal is received. When both the output clock driver is turned on, and an input clock signal is being received, the simultaneous bidirectional port is synchronized, and communication between integrated circuits can take place.

Abstract: A voltage multiplier circuit includes a voltage-to-current converter, a current multiplier, and load devices. The voltage-to-current converter receives a differential input voltage, and produces a differential current. The differential current is received by the current multiplier, which produces a scaled output current. The amount of scaling is provided by a digital control word. Load devices produce a differential output voltage from the scaled output current. Multiple voltage-to-current converters and current multipliers can be coupled in parallel so that the scaled output currents sum.

Abstract: A current mode driver includes a tail current device, a differential pair of input transistors, cascode output transistors, and pre-charge circuits to charge cascode nodes between the differential pair of input transistors and the cascode output transistors. The current mode driver is driven by CMOS drivers that alternately turn the input transistors on and off. A wide-swing bias circuit provides bias voltages for the current mode driver. This bias voltage for the tail current device is closely matched to provide current matching between the bias circuit and the current mode driver.

Abstract: A method for minimizing jitter using substantially matched, controlled, delay elements is disclosed. The method includes generating an internal loop-timing reference, and controlling elements outside of the loop with the internal loop-timing reference generated. In one embodiment the outside elements are substantially identical to those internal to the closed-loop. Controlled delay elements for preconditioning and distributing closed-loop inputs and outputs, using the same control reference used by internal loop elements are disclosed.

Abstract: A CMOS amplifier for optoelectronic receivers, the amplifier comprises two transimpedance amplifiers and two differential amplifier latches. One of the two transimpedance amplifiers has an input port to receive a current signal, such as, for example, a current signal from a photodetector, and provides a output voltage indicative of the received current signal. The other of the two transimpedance amplifiers may be viewed as having no input signal, so that it provides a reference voltage. The two transimpedance amplifiers are in close proximity to each other, so that power supply noise is a common mode signal in the output voltages of the two transimpedance amplifiers. The differential amplifier latches reject the common mode signal by comparing the reference voltage to the output voltage, and provide output logic voltages indicative of binary hard decisions.

Abstract: A current mode output driver includes a pre-driver for pre-equalization. The current mode output driver drives a transmission line with an alternating current (AC) signal and a direct current (DC) signal. Characteristics of the transmission line are measured by comparing a received amplitude of the AC signal and a received amplitude of the DC signal. A ratio of the AC received amplitude to the DC received amplitude is compared to ratios derived from possible equalization settings to determine an equalization setting appropriate to equalize the channel.

Abstract: In some embodiments, the invention involves multiple integrated circuit stubs coupled in series. At least one of the integrated circuit stubs including first conductors to receive signals from a first adjacent one of the integrated circuit stubs, second conductors to provide signals to a second adjacent one of the integrated circuit stubs, and third conductors to provide signals to an integrated circuit chip. The integrated circuit stubs include first drivers and second drivers coupled to the first, second, and third conductors, wherein the first drivers receive the external signals from the first conductors and drive them onto the second conductors and the second drivers receive signals from the first conductors and drive them onto the third conductors.

Abstract: A synchronous clock generator for an integrated circuit is described in which a delay lock loop circuit may be used to delay a first input signal. A delay circuit is coupled to the delay lock loop circuit and receives a control voltage from the delay lock loop circuit, which is used to delay a second input signal. The first and second input signal may be complimentary.

Abstract: A current reference with reduced sensitivity to process variations includes a variable resistor and a control transistor. The control transistor has a current from source-to-drain that is provided by a current mirror. The current mirror also provides a current to a variable resistor that is coupled gate-to-source to the control transistor. A control loop circuit measures the reference current provided by the current mirror and modifies the resistance value of the variable resistor in response. An external precision resistor is used to measure the reference current, and current variations as a result of process variations are reduced.

Abstract: A simultaneous bidirectional port coupled to a bus combines a synchronization circuit and a clock circuit. The synchronization and clock circuit synchronizes the port with another simultaneous data port coupled to the same bus. A clock driver circuit is provided that is capable of being turned on and off. Prior to synchronization, the clock driver is off, and after synchronization, the clock driver is on. A clock receiver circuit includes a clock detection circuit to detect the presence of an input clock signal. When an integrated circuit is ready to communicate, the output clock driver is turned on and the clock detection circuit is monitored to determine when an input clock signal is received. When both the output clock driver is turned on, and an input clock signal is being received, the simultaneous bidirectional port is synchronized, and communication between integrated circuits can take place.

Abstract: A signal propagation system includes a plurality of memory modules that receive a clock signal from a system clock generator. A backplane has a first clock line that propagates a clock signal from the generator to a first memory module of the plurality of memory modules. The backplane may also include a second line that propagates a clock signal between the first and a second memory module of the plurality. The first memory module may include an onboard transmission line that propagates a clock signal between respective first and second clock lines of the backplane.

Abstract: A system and method for encoding and receiving data is provided. The data is encoded as a pulse amplitude modulated signal such that the amplitude signals do not transition from the highest signal level to the lowest signal level and do not transition from the lowest signal level to the highest signal level. The encoding and decoding is performed in some embodiments via a lookup table, and in further embodiments is designed to minimize the step between sequential pulse amplitude modulated symbols.

Abstract: The invention provides an apparatus, method, and means for maintaining a constant slew rate while providing pre-emphasis, to adapt a push-pull voltage driver to the interconnect that it is driving. In an aspect, the invention modifies a driver output voltage amplitude, providing a small swing out for low frequency signals, and a large swing out for high frequency signals, such that low frequency signals and high frequency signals reach a receiver with equal amplitude. In an aspect, a slew rate control, having a delay mixer, selects and individually transmits to individual segments of a driver leg, at a desired time, one of output data and a signal for a pre-emphasis version of output data. In an aspect, the invention maintains a matched direct current termination impedance to the characteristic impedance of a transmission line being driven.

Abstract: A CMOS amplifier for optoelectronic receivers, the amplifier comprises two transimpedance amplifiers and two differential amplifier latches. One of the two transimpedance amplifiers has an input port to receive a current signal, such as, for example, a current signal from a photodetector, and provides a output voltage indicative of the received current signal. The other of the two transimpedance amplifiers may be viewed as having no input signal, so that it provides a reference voltage. The two transimpedance amplifiers are in close proximity to each other, so that power supply noise is a common mode signal in the output voltages of the two transimpedance amplifiers. The differential amplifier latches reject the common mode signal by comparing the reference voltage to the output voltage, and provide output logic voltages indicative of binary hard decisions.

Abstract: A simultaneous bidirectional port circuit includes a current mode output driver for driving an output node and a current mode return driver for driving a differential receiver. Variable impedance termination devices are included to provide terminations for both the current mode output driver and current mode return driver. A control circuit and method set the impedance value of the variable impedance termination devices by comparing voltage values at the output of the current mode output driver and current mode return driver.

Abstract: A current mirror includes an input node to receive an input current, an output node to produce an output current, and a reference node. The current mirror also includes a potential reduction unit to allow the voltage at the input node to be less than the voltage at the reference node.

Abstract: A multiplier includes an input stage to receive input signals to provide currents at a plurality of source nodes. An output stage includes a plurality of transistors groups, each of the transistor groups has a plurality of binary weighted transistor pairs. A select unit selects the binary weighted transistor pairs based on binary code signals so that each transistor pair passes a current from one of the source nodes to either a reference node or a summing node.