International Business Machines Corporation

Joseph M Stevens

Hayden C Cranford, Jr

Westerfield John Ficken

Martin L Schmatz

Vernon Roberts Norman

Stacy J Garvin

Hayden Cranford

Paul Alan Owczarski

Daniel P Greenberg

Todd Morgan Rasmus

David A Freitas

A test circuit for a serial link receiver includes a first current source coupled to a first input of the serial link receiver, and a second current source coupled to a second input of the serial link receiver. The first current source is symmetrically matched to the second current source. A first switch of the first current source is turned on to permit a charge-retaining mechanism thereof to be charged. A second switch of the first current source is turned on to permit the retained charge retained to be asserted on the first input. The charge turns on a control switch of the first current source, through which the charge is asserted on the first input. A charge-draining mechanism of the first current source is turned on to thereafter permit the charge to be drained in a controlled manner after the charge has been asserted.

Test circuit for serial link receiver

A method and apparatus for extending the common mode range of a differential amplifier. A circuit has a common mode detection circuit, a common mode voltage inversion circuit, and a differential amplifier. The common mode detection circuit receives a differential signal and detects a common mode voltage. The common mode voltage inversion circuit is coupled to the common mode detection circuit. The common mode voltage inversion circuit has an input node that receives the common mode voltage and an output node that outputs body voltage, wherein the common mode voltage inversion circuit creates an inverse relationship between the common mode voltage and the body voltage. The differential amplifier includes a differential pair of transistors that have a pair of body terminals coupled to the output node of the common mode voltage inversion circuit.

Adaptive common mode bias for differential amplifier input circuits

A circuit device and method for designing a serial link receiver, which accommodates a wide input voltage range and provides tolerance to high termination voltages. The receiver is designed with a pair of RC networks connected inline between the input and the preamplifier and a common mode feedback loop, which monitors shifts in the common mode voltage and adjusts the inputs provided to the preamplifier. The circuit device maintains a flat bandwidth to accommodate all signaling rates.

Serial link receiver with wide input voltage range and tolerance to high power voltage supply

The present analog invention is related to a unified digital architecture comprising logic transmitter portions and logic receiver portions. A unified serial link system and method for transmitting digital data across wired media including a transmitter and a receiver portion is provided, one of the transmitter portion and receiver portion comprising a phase locked loop (PLL) circuit. The PLL circuit comprises a voltage control oscillator, a frequency divider, a phase-frequency detector, a charge pump and a multi-pole loop filter. One embodiment comprises a dual loop PLL having a digital coarse loop and an analog fine loop.

Analog unidirectional serial link architecture

Aspects for increased noise immunity for clocking signals in high speed digital systems are described. The aspects include buffering a differential clock signal with a single buffer circuit for a plurality of load circuits and configuring the single buffer circuit to adjust to alterations in the number of load circuits receiving the differential clock signal. The configuring achieves a constant bandwidth and voltage level for the clock signal output while adjusting to alterations in the number of load circuits.

Method and circuit for increased noise immunity for clocking signals in high speed digital systems

A unified serial link system and method for transmitting digital data across wired media including a transmitter and a receiver. The system comprises a phase locked loop (PLL) control circuit, a phase rotator circuit, a phase buffer circuit, and an equalization driver circuit. The phase rotator circuit is configured to acquire a clock phase from the phase locked loop control circuit and modulo shift the clock phase into a desired phase angle. One embodiment comprises a dual loop PLL having a digital coarse loop and an analog fine loop, a multi-stage voltage controlled oscillator, a voltage comparator, a PLL control logic, a digital to analog counter and a low pass filter. The fine loop includes the oscillator, a frequency divider, a phase-frequency detector, a charge pump and a loop filter.

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Morrisville, NC, United States of America

Joseph M Stevens