Patent application number | Description | Published |
20080197906 | Reference clock receiver compliant with LVPECL, LVDS and PCI-Express supporting both AC coupling and DC coupling - A reference clock receiver structure according to the invention is provided. The structure preferably includes an input buffer that is formed from a PMOS differentiated pair of transistors and a first supply voltage. The PMOS differential pair receives a pair of differential inputs, and produces a pair of differential outputs. The structure also includes a level shifter that is coupled to receive the pair of differential outputs from the input buffer to provide gain to the pair of differential outputs to form a gained pair of differential outputs. The level shifter that includes a second supply voltage. The second supply voltage may have a smaller magnitude than the first supply voltage. Finally, the structure includes a CMOS buffer that is coupled to receive the gained pair of differential outputs. The CMOS buffer boosts the gained pair of differential outputs and converts the gained differential pair outputs into a single signal. | 08-21-2008 |
20090279597 | DIGITAL EQUALIZER FOR HIGH-SPEED SERIAL COMMUNICATIONS - Incoming data at a high-speed serial receiver is digitized and then digital signal processing (DSP) techniques may be used to perform digital equalization. Such digital techniques may be used to correct various data anomalies. In particular, in a multi-channel system, where crosstalk may be of concern, knowledge of the characteristics of the other channels, or even the data on those channels, may allow crosstalk to be subtracted out. Knowledge of data channel geometries, particularly in the context of backplane transmissions, may allow echoes and reflections caused by connectors to be subtracted out. As data rates increase, fractional rate processing can be employed. For example, the analog-to-digital conversion can be performed at half-rate and then two DSPs can be used in parallel to maintain throughput at the higher initial clock rate. At even higher rates, quadrature techniques can allow analog-to-digital conversion at quarter-rate, with four DSPs used in parallel. | 11-12-2009 |
20090309240 | RETURN LOSS TECHNIQUES IN WIREBOND PACKAGES FOR HIGH-SPEED DATA COMMUNICATIONS - A wirebond package configured to reduce wirebond return loss is presented. An integrated circuit of interest with rows of bonding pads is bonded to a surface of the wirebond package. The surface of wirebond package has columns of bonding pads, which are configured to transmit or receive signals, power, and ground to and/or from the wirebond package to the integrated circuit. Corresponding die pads on the integrated circuit and bonding pads of the wirebond package are coupled using conductive lines. The conductive lines carrying the active signal has coplanar adjacent ground lines on opposing sides of active signal line and the distance between active signal line and the coplanar adjacent ground lines is tapered. | 12-17-2009 |
20090315627 | PHASE-LOCKED LOOP CIRCUITRY WITH MULTIPLE VOLTAGE-CONTROLLED OSCILLATORS - Configurable phase-locked loop circuitry is provided. The phase-locked loop circuitry may include a buffer having a buffer output and a multiplexer having inputs and an output. The phase-locked loop circuitry may include multiple voltage-controlled oscillators. The phase-locked loop circuitry may be configured to switch a desired one of the voltage-controlled oscillators into use. Each voltage-controlled oscillator may be controlled by control signals applied to a control input for that voltage-controlled oscillator. The control input of each voltage-controlled oscillator may be connected to the buffer output. The output of each voltage-controlled oscillator may be connected to a respective one of the multiplexer inputs. Power-down transistors may be used to disable unused voltage-controlled oscillators to conserve power. The power-down transistors and the multiplexer may be controlled by signals from programmable elements. One or more of the voltage-controlled oscillators may be implemented using a separate integrated circuit connected using through-silicon vias. | 12-24-2009 |
20090322435 | DIGITALLY CONTROLLED OSCILLATORS - Oscillator circuitry is provided that is based on a ring of inverters. The ring of inverters may be single-ended or differential inverters. Digitally controlled adjustable load capacitors may be provided at inverter outputs to tune the oscillator circuitry. Each digitally controlled adjustable load capacitor may be formed from multiple varactors connected in parallel. Each varactor may have a control input that receives a digital control signal. The digitally controlled adjustable load capacitors in a given oscillator may be adjusted in unison to produce the same capacitance value for each capacitor or may be adjusted individually so that they produce different capacitance values. The inverters may include common-mode-gain reduction features such as series-connected current sources, series-connected resistors, and cross-coupled negative feedback transistors. | 12-31-2009 |
20100073054 | Techniques For Digital Loop Filters - A digital loop filter includes a fine control circuit and a coarse control circuit. The fine control circuit adjusts a phase of a feedback clock signal by a first phase adjustment in response to a first phase error signal that indicates a sign of a phase error between a reference clock signal and the feedback clock signal. The coarse control circuit adjusts the phase of the feedback clock signal by a second phase adjustment in response to a second phase error signal. The second phase adjustment is larger than the first phase adjustment. The second phase error signal indicates a magnitude of a phase error between the reference clock signal and the feedback clock signal. | 03-25-2010 |
20110309886 | DIGITALLY CONTROLLED OSCILLATORS - Oscillator circuitry is provided that is based on a ring of inverters. The ring of inverters may be single-ended or differential inverters. Digitally controlled adjustable load capacitors may be provided at inverter outputs to tune the oscillator circuitry. Each digitally controlled adjustable load capacitor may be formed from multiple varactors connected in parallel. Each varactor may have a control input that receives a digital control signal. The digitally controlled adjustable load capacitors in a given oscillator may be adjusted in unison to produce the same capacitance value for each capacitor or may be adjusted individually so that they produce different capacitance values. The inverters may include common-mode-gain reduction features such as series-connected current sources, series-connected resistors, and cross-coupled negative feedback transistors. | 12-22-2011 |