Pravin B Patel

US Patent:

7394281, Jul 1, 2008

Filed:

Jan 31, 2008

Appl. No.:

12/023659

Inventors:

Justin P. Bandholz - Cary NC, US
Moises Cases - Austin TX, US
Bradley D. Herman - Cary NC, US
Erdem Matoglu - Austin TX, US
Bhyrav M. Mutnury - Austin TX, US
Thomas D. Pahel - Chapel Hill NC, US
Pravin S. Patel - Cary NC, US
Nam H. Pham - Round Rock TX, US
Christopher C. West - Raleigh NC, US

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

H03K 17/16

US Classification:

326 22, 326 26, 326 83, 326 92

Abstract:

A bi-directional universal serial bus (“USB”) circuit for boosting a signal on a USB bus disclosed. The circuit includes a first stage inverting buffer coupled to a second stage inverting buffer to form a non-inverting buffer circuit. A high pass filter is coupled in series with the non-inverting buffer circuit to provide AC coupling to the USB bus and to allow fast signal edges through the circuit. The booster circuit is arranged to improve signal quality over a USB bus to allow additional USB devices and longer USB busses to be utilized.

US Patent:

7474117, Jan 6, 2009

Filed:

May 27, 2008

Appl. No.:

12/127165

Inventors:

Justin P. Bandholz - Cary NC, US
Moises Cases - Austin TX, US
Bradley D. Herman - Cary NC, US
Erdem Matoglu - Austin TX, US
Bhyrav M. Mutnury - Austin TX, US
Thomas D. Pahel - Chapel Hill NC, US
Pravin S. Patel - Cary NC, US
Nam H. Pham - Round Rock TX, US
Christopher C. West - Raleigh NC, US

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

H03K 17/16

US Classification:

326 22, 326 92

Abstract:

A method of transmitting a signal on a bi-directional universal serial bus (“USB”) circuit for boosting a signal on a USB bus disclosed. The circuit includes a first stage inverting buffer coupled to a second stage inverting buffer to form a non-inverting buffer circuit. A high pass filter is coupled in series with the non-inverting buffer circuit to provide AC coupling to the USB bus and to allow fast signal edges through the circuit. The booster circuit is arranged to improve signal quality over a USB bus to allow additional USB devices and longer USB busses to be utilized.

US Patent:

7525319, Apr 28, 2009

Filed:

Aug 28, 2008

Appl. No.:

12/200208

Inventors:

Rubina Firdaus Ahmed - Cary NC, US
Moises Cases - Austin TX, US
Bradley Donald Herrman - Cary NC, US
Kent Barclay Howieson - Austin TX, US
Bhyrav Murthy Mutnury - Austin TX, US
Pravin Patel - Cary NC, US
Peter Robert Seidel - Cary NC, US

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G01R 31/04
G01R 31/02
G01R 31/28

US Classification:

324538, 324754, 714734

Abstract:

A method of electrically qualifying high speed printed circuit board (PCB) connectors includes mounting a PCB connector on a test card, sending bit patterns through a first portion of the test card, evaluating a waveform on a sense signal on a second portion of the test card for the bit patterns launched on said first portion of the test card to measure common mode noise, and comparing the measured common mode noise of the second portion of the test card to a golden standard performed on a pre-qualified connector. The first portion of the test card comprises connectors to inject bit patterns. The second portion of the test card includes a split plane which induces common mode noise on a sense signal, the sense signal, and a termination pack. If the measured common mode noise on the PCB connector is worse than the golden standard, then the PCB connector is disqualified. If the measured common mode noise on the PCB connector is as good as or better than the golden standard, then the PCB connector is qualified.

US Patent:

7667980, Feb 23, 2010

Filed:

Oct 10, 2006

Appl. No.:

11/539990

Inventors:

Brian A. Baker - Raleigh NC, US
James E. Hughes - Apex NC, US
Pravin Patel - Cary NC, US
Challis L. Purrington - Raleigh NC, US
Christopher C. West - Raleigh NC, US

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

H05K 7/00

US Classification:

361782, 174262

Abstract:

Printed circuit boards for countering signal distortion are disclosed that include: a conductive pathway on a printed circuit board between a transmitter and a receiver, the conductive pathway comprised of traces and vias connected together for conductive transfer of a signal from the transmitter to the receiver; a parasitic element on the printed circuit board, the parasitic element having a parasitic effect that distorts the signal; and one or more passive elements mounted adjacent to the conductive pathway without connecting to the conductive pathway, the passive elements having a corrective effect to reduce the distortion from the parasitic effect on the signal.

US Patent:

7906950, Mar 15, 2011

Filed:

Nov 13, 2008

Appl. No.:

12/270477

Inventors:

Justin P. Bandholz - Cary NC, US
Nickolas J. Gruendler - Pflugerville TX, US
Pravin Patel - Cary NC, US

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G05F 1/00
G05D 17/00

US Classification:

323283, 700298

Abstract:

Tuning a switching power supply, the power supply including a switching transistor; a filter circuit; a pulse generator that drives the switching transistor; a programmable filter connected to the output of the filter circuit; a digital signal processor (‘DSP’) connected to the output of the filter circuit, the DSP configured to program the programmable filter; and a tuning control circuit connected to the output of the filter circuit, to the pulse generator, and to the DSP; including calculating by the DSP, from sampled voltage values of a tuning pulse driven through the filter circuit by the pulse generator, the actual impedance of the filter circuit; and programming, by the DSP, the programmable filter, setting the combined impedance of the filter circuit and the programmable filter to the design impedance of the filter circuit.

US Patent:

7956688, Jun 7, 2011

Filed:

Oct 7, 2009

Appl. No.:

12/574923

Inventors:

Rubina F. Ahmed - Cary NC, US
Bradley D. Herrman - Cary NC, US
Pravin Patel - Cary NC, US
Peter R. Seidel - Cary NC, US

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

H03F 3/45
H03K 19/094

US Classification:

330254, 330258, 326 82, 326 84, 326 86

Abstract:

Embodiments of the invention include a common mode cancellation circuit and method for correcting signal skew in a differential circuit. According to one embodiment, an op amp circuit is used to correct the mismatch between transmission line lengths in the differential circuit. The CMCC can be embodied as an ASIC and added on to an existing differential signaling systems to correct and compensate for board wiring skew or other causes of phase misalignment. The result is restoration of the cross-over intersection of the plus and minus signals of the differential pair closer to the common voltage level point, as if the signals had been in phase.

US Patent:

7992030, Aug 2, 2011

Filed:

May 9, 2007

Appl. No.:

11/746102

Inventors:

Henry G. McMillan - Raleigh NC, US
Pravin Patel - Cary NC, US
Challis L. Purrington - Raleigh NC, US
Gwendolyn R. Tobin - Jacksonville FL, US
Christopher C. West - Raleigh NC, US
Ivan R. Zapata - Cary NC, US

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G06F 1/00

US Classification:

713500, 713502, 375238

Abstract:

Embodiments of the invention address deficiencies of the art in respect to digital signal transmissions and provide a novel and non-obvious fall time accelerator circuit for use in a USB interface. In one embodiment of the invention, the USB interface can include a USB port driver coupled to a host controller driver over a USB bus. The USB interface also can include a fall time accelerator circuit coupled to the USB bus between the USB port driver and the host controller driver. The fall time accelerator circuit can include a pulse signal generator coupled to an inbound signal path from the USB bus and arranged to generate a tunable pulse upon detecting a falling edge of a digital signal on the inbound signal path. The circuit further can include an active timer additionally coupled to the inbound signal path to hold the tunable pulse for a set period of time. Finally, the circuit can include a falling drive signal strengthener coupled to an outbound signal path from the pulse signal generator arranged to release the tunable pulse on the outbound signal path onto the USB bus.

US Patent:

8106666, Jan 31, 2012

Filed:

Mar 12, 2009

Appl. No.:

12/402806

Inventors:

Rubina F. Ahmed - Cary NC, US
Moises Cases - Austin TX, US
Bradley D. Herrman - Cary NC, US
Bhyrav M. Mutnury - Austin TX, US
Pravin Patel - Cary NC, US
Peter R. Seidel - Cary NC, US

Assignee:

International Business Macines Corporation - Armonk NY

International Classification:

G01R 31/02

US Classification:

324537, 324228, 324691

Abstract:

Testing an electrical component, the component including a printed circuit board (‘PCB’) with a number of traces, the traces organized in pairs with each trace of a pair carrying current in opposite directions and separated from one another by a substrate layer of the PCB, where testing of the electrical component includes: dynamically and iteratively until a present impedance for a pair of traces of the component is greater than a predetermined threshold impedance: increasing, by an impedance varying device at the behest of a testing device, magnetic field strength of a magnetic field applied to the pair of traces by the impedance varying device, including increasing the present impedance of the pair of traces; measuring, by the testing device, one or more operating parameters; and recording, by the testing device, the measurements of the operating parameters.