Fred F Chen

US Patent:

6982587, Jan 3, 2006

Filed:

Oct 1, 2002

Appl. No.:

10/261875

Inventors:

Fred F. Chen - San Francisco CA, US
Vladimir M. Stojanovic - Stanford CA, US

Assignee:

Rambus Inc. - Los Altos CA

International Classification:

G06G 7/12

US Classification:

327355, 327361, 327352, 326 30

Abstract:

A signaling circuit having reduced parasitic capacitance. The signaling circuit includes a plurality of driver circuits each having an output coupled to a first output node, and a plurality of select circuits each having an output coupled to a control input of a corresponding one of the driver circuits. Each of the select circuits includes a control input to receive a respective select signal and a plurality of data inputs to receive a plurality of data signals. Each of the select circuits is adapted to select, according to the respective select signal, one of the plurality of data signals to be output to the control input of the corresponding one of the driver circuits.

US Patent:

7030657, Apr 18, 2006

Filed:

May 21, 2004

Appl. No.:

10/851505

Inventors:

Vladimir M. Stojanovic - Stanford CA, US
Andrew Ho - Palo Alto CA, US
Anthony Bessios - Fremont CA, US
Fred F. Chen - San Francisco CA, US
Elad Alon - Saratoga CA, US
Mark A. Horowitz - Menlo Park CA, US

Assignee:

Rambus Inc. - Los Altos CA

International Classification:

H03K 19/0175

US Classification:

326 87, 326 83

Abstract:

A signaling system having an equalizing transmitter and equalizing receiver. The equalizing transmitter transmits a signal to a receive circuit. A first sampling circuit within the equalizing receiver samples the signal to determine whether the signal exceeds a first threshold, and a second sampling circuit within the equalizing receiver samples the signal to determine whether the signal exceeds a second threshold. A drive strength of the equalizing transmitter and a drive strength of an equalizing signal driver within the equalizer are adjusted based, at least in part, on whether the first signal exceeds the first and second thresholds.

US Patent:

7126378, Oct 24, 2006

Filed:

Dec 17, 2003

Appl. No.:

10/740087

Inventors:

Vladimir M. Stojanovic - Stanford CA, US
Andrew C. C. Ho - Palo Alto CA, US
Anthony Bessios - Fremont CA, US
Fred F. Chen - San Francisco CA, US
Elad Alon - Saratoga CA, US
Mark A. Horowitz - Menlo Park CA, US

Assignee:

Rambus, Inc. - Los Altos CA

International Classification:

H03K 19/0175

US Classification:

326 87, 326 83, 326 27

Abstract:

A signaling system having first and second sampling circuits and an output driver circuit. The first sampling circuit samples a first signal generated by the output driver circuit to determine whether the first signal exceeds a first threshold. The second sampling circuit samples the first signal to determine whether the first signal exceeds a second threshold. The drive strength of the output driver circuit is adjusted based, at least in part, on whether the first signal exceeds the first and second thresholds, and the second threshold is adjusted based, at least in part, on whether the first signal exceeds the second threshold.

US Patent:

7199615, Apr 3, 2007

Filed:

Mar 21, 2006

Appl. No.:

11/386984

Inventors:

Vladimir M. Stojanovic - Stanford CA, US
Andrew Ho - Palo Alto CA, US
Anthony Bessios - Fremont CA, US
Fred F. Chen - San Francisco CA, US
Elad Alon - Saratoga CA, US
Mark A. Horowitz - Menlo Park CA, US

Assignee:

Rambus Inc. - Los Altos CA

International Classification:

H03K 19/0175

US Classification:

326 82, 326 26

Abstract:

A signaling system having an equalizing transmitter and equalizing receiver. The equalizing transmitter transmits a signal to a receive circuit. A first sampling circuit within the equalizing receiver samples the signal to determine whether the signal exceeds a first threshold, and a second sampling circuit within the equalizing receiver samples the signal to determine whether the signal exceeds a second threshold. A drive strength of the equalizing transmitter and a drive strength of an equalizing signal driver within the equalizer are adjusted based, at least in part, on whether the first signal exceeds the first and second thresholds.

US Patent:

7233164, Jun 19, 2007

Filed:

Jun 23, 2004

Appl. No.:

10/875086

Inventors:

Vladimir M. Stojanovic - Stanford CA, US
Andrew Ho - Palo Alto CA, US
Fred F. Chen - San Francisco CA, US
Bruno W. Garlepp - San Jose CA, US

Assignee:

Rambus Inc. - Los Altos CA

International Classification:

H03K 17/16

US Classification:

326 22, 326 82

Abstract:

A receive circuit having a sampling circuit and a threshold generating circuit. The sampling circuit generates a first sample value having either a first state or a second state according whether an incoming signal exceeds a first threshold level, the first threshold level corresponding to a first threshold value. The threshold generating circuit combines a first control value and a second control value to generate the first threshold value and provides the first threshold value to the sampling circuit.

US Patent:

7292629, Nov 6, 2007

Filed:

Jul 12, 2002

Appl. No.:

10/195129

Inventors:

Jared L. Zerbe - Woodside CA, US
Vladimir M. Stojanovic - Stanford CA, US
Fred F. Chen - San Francisco CA, US

Assignee:

Rambus Inc. - Los Altos CA

International Classification:

H03H 7/30
H03H 7/40
H03K 5/159

US Classification:

375229, 375232, 375296

Abstract:

A signaling circuit having a selectable-tap equalizer. The signaling circuit includes a buffer, a select circuit and an equalizing circuit. The buffer is used to store a plurality of data values that correspond to data signals transmitted on a signaling path during a first time interval. The select circuit is coupled to the buffer to select a subset of data values from the plurality of data values according to a select value. The equalizing circuit is coupled to receive the subset of data values from the select circuit and is adapted to adjust, according to the subset of data values, a signal level that corresponds to a data signal transmitted on the signaling path during a second time interval.

US Patent:

7292637, Nov 6, 2007

Filed:

Dec 17, 2003

Appl. No.:

10/739823

Inventors:

Andrew Ho - Palo Alto CA, US
Vladimir Stojanovic - Stanford CA, US
Fred F. Chen - San Francisco CA, US
Elad Alon - Saratoga CA, US
Mark A. Horowitz - Menlo Park CA, US

Assignee:

Rambus Inc. - Los Altos CA

International Classification:

H04B 3/00
H04B 1/10
H04B 1/18
H03D 1/04

US Classification:

375257, 375346, 455283, 455280

Abstract:

Described are communication systems that convey differential and common-mode signals over the same differential channel. Noise-tolerant communication schemes use low-amplitude common-mode signals that are easily rejected by differential receivers, thus allowing for very high differential data rates. Some embodiments employ the common-mode signals to transmit backchannel signals for adjusting the characteristics of the differential transmitter. Backchannel control signals are effectively conveyed even if the forward channel transmitter is so maladjusted that the received differential data is unrecognizable. Systems in accordance with the above-described embodiments obtain these advantages without additional pins or communications channels, and are compatible with both AC-coupled and DC-coupled communications channels. Data coding schemes and corresponding data recovery circuits eliminate the need for complex, high-speed CDR circuits.

US Patent:

7308058, Dec 11, 2007

Filed:

Mar 19, 2004

Appl. No.:

10/805413

Inventors:

Jared L. Zerbe - Woodside CA, US
Carl W. Werner - Los Gatos CA, US
William F. Stonecypher - San Jose CA, US
Fred F. Chen - San Francisco CA, US

Assignee:

Rambus Inc. - Los Altos CA

International Classification:

H03K 9/02

US Classification:

375353, 375286, 375259

Abstract:

Provided are a method and apparatus for high-speed, multi-mode PAM symbol transmission. A multi-mode PAM output driver drives one or more symbols, the number of levels used in the PAM modulation of the one or more symbols depending on the state of a PAM mode signal. Additionally, the one or more symbols are driven at a symbol rate, the symbol rate selected in accordance with the PAM mode signal so that a data rate of the driven symbols is constant with respect to changes in the state of the PAM mode signal. Further provided are methods for determining the optimal number of PAM levels for symbol transmission and reception in a given physical environment.