Patents by Inventor Derek Tam

Derek Tam has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Publication number: 20100259300
    Abstract: In one embodiment, a circuit for providing a tail current for a line driver includes an adjustable current source. The adjustable current source includes a number of current source cells coupled together in a parallel configuration, where the current source cells are configured to provide the tail current for the line driver in response to a digital control signal. The circuit can further include a digital core coupled to the adjustable current source, where the digital core provides the digital control signal. The digital control signal provides a number of bits, where each bit controls one of the current source cells. In one embodiment, a current source cell can comprise a number of current source sub-cells. The current source cells can be configured to provide the tail current for the line driver in response to the digital control signal when the line driver is operating in a class AB mode.
    Type: Application
    Filed: April 8, 2009
    Publication date: October 14, 2010
    Applicant: BROADCOM CORPORATION
    Inventors: Joseph Aziz, Andrew Chen, Ark-Chew Wong, Derek Tam
  • Publication number: 20100259340
    Abstract: According to one exemplary embodiment, an active termination circuit includes at least one active termination branch, where the at least one active termination branch includes at least one transistor for providing an active termination output. The at least one active termination branch further includes an amplifier driving the at least one transistor, where the amplifier has a non-inverting input coupled to the active termination output via a feedback network. The amplifier controls a current flowing through the at least one transistor so as to provide the active termination output. The active termination output can be provided at a drain of the at least one transistor, where a source of the at least one transistor is coupled to ground through a degeneration transistor and a tail current sink.
    Type: Application
    Filed: April 8, 2009
    Publication date: October 14, 2010
    Applicant: BROADCOM CORPORATION
    Inventors: Joseph Aziz, Andrew Chen, Derek Tam, Ark-Chew Wong, Agnes Neves Woo, Marcel Lugthart
  • Publication number: 20100225362
    Abstract: According to one exemplary embodiment, a transmitter module includes a line drive including a current digital-to-analog converter, where the line driver provides an analog output waveform. The current digital-to-analog converter receives a digitally filtered input waveform including at least two voltage steps. The at least two voltage steps of the digitally filtered input waveform cause a rise time of the analog output waveform to have a reduced dependency on process, voltage, and temperature variations in the line driver, while meeting stringent rise time requirements. The digitally filtered input waveform has an initial voltage level and a final voltage level, where the final voltage level is substantially equal to a sum of the at least two voltage steps of the digitally filtered input waveform.
    Type: Application
    Filed: March 9, 2009
    Publication date: September 9, 2010
    Applicant: BROADCOM CORPORATION
    Inventors: Andrew Chen, Joseph Aziz, Derek Tam
  • Publication number: 20090253240
    Abstract: A circuit with dielectric thicknesses is presented that includes a low-pass filter including one or more semiconductor devices having a thick gate oxide layer, while further semiconductor devices of the circuit have thin gate oxide layers. The low-pass filter semiconductor device includes an N-type substrate, a P-type region formed on the N-type substrate, a thick gate oxide layer formed over the P-type region, a P+ gate electrode formed over the thick gate oxide layer and coupled to a first voltage supply line, and P+ pick-up terminals formed in the P-type region adjacent the gate electrode and coupled to a second voltage supply line. The low-pass filter semiconductor device acts as a capacitor, whereby a gate-to-substrate voltage is maintained at less than zero volts to maintain a stable control voltage for the circuit.
    Type: Application
    Filed: June 15, 2009
    Publication date: October 8, 2009
    Applicant: Broadcom Corporation
    Inventors: Derek Tam, Jasmine Cheng, Jungwoo Song, Takayuki Hayashi
  • Patent number: 7547956
    Abstract: A circuit with dielectric thicknesses is presented that includes a low-pass filter including one or more semiconductor devices having a thick gate oxide layer, while further semiconductor devices of the circuit have thin gate oxide layers. The low-pass filter semiconductor device includes an N-type substrate, a P-type region formed on the N-type substrate, a thick gate oxide layer formed over the P-type region, a P+ gate electrode formed over the thick gate oxide layer and coupled to a first voltage supply line, and P+ pick-up terminals formed in the P-type region adjacent the gate electrode and coupled to a second voltage supply line. The low-pass filter semiconductor device acts as a capacitor, whereby a gate-to-substrate voltage is maintained at less than zero volts to maintain a stable control voltage for the circuit.
    Type: Grant
    Filed: October 28, 2004
    Date of Patent: June 16, 2009
    Assignee: Broadcom Corporation
    Inventors: Derek Tam, Jasmine Cheng, Jungwoo Song, Takayuki Hayashi
  • Publication number: 20080253356
    Abstract: Aspects of a method and system for a power reduction scheme for Ethernet PHYs are provided. An Ethernet PHY in a link partner may disable transmission via a transmit DAC integrated during an inactive connection, 10Base-T autonegotiation operation, and/or active 10Base-T connection with no data packet transmission. The DAC may be a voltage mode or current mode DAC. The PHY or a MAC device may determine when to disable transmission via the DAC. In this regard, the PHY or the MAC device may generate appropriate signals for disabling the transmission. The DAC may be enabled for transmission by the PHY or the MAC device when a connection becomes active or when an active 10Base-T connection is ready to transmit data. Moreover, the PHY may enable transmission via the DAC when operating in a forced 10Base-T mode of operation and the connection to the link partner is active.
    Type: Application
    Filed: April 11, 2007
    Publication date: October 16, 2008
    Inventors: Mark Berman, Manolito Catalasan, Ovidiu Bajdechi, Christopher M. Ward, Bruce H. Conway, Derek Tam, Frank van der Goes
  • Publication number: 20070112978
    Abstract: System and methods for providing multimedia message service (MMS) interoperability between an initiating carrier and a destination carrier. A transcoding facility receives an MMS message from an initiating carrier and accesses a number portability database to determine an identity of a destination carrier to which the MMS message is intended to be sent and a carrier profile repository to obtain a carrier profile for the destination carrier, the carrier profile including information regarding an MMS format acceptable to the destination carrier.
    Type: Application
    Filed: January 9, 2007
    Publication date: May 17, 2007
    Inventors: Derek Tam, James Farrow, William Duddley, Thilo Rusche, Brian Beggerly, Robert Lovell
  • Patent number: 7005898
    Abstract: A programmable divider includes a synchronous counter configured to process an input clock signal and produce first output signals in response the input clock signal. A number of logic devices are coupled to the synchronous counter and configurable to receive the first output signals and correspondingly produce second output signals. Also included is a multiplexer that is configured to receive the second output signals and has an output coupled to an input of the synchronous counter. In the programmable divider, characteristics of the synchronous counter are selectable based upon a particular number of the logic devices configured.
    Type: Grant
    Filed: September 22, 2004
    Date of Patent: February 28, 2006
    Assignee: Broadcom Corporation
    Inventors: Derek Tam, Takayuki Hayashi
  • Publication number: 20050216403
    Abstract: System and method for providing augmented billing services. Where a billing system cannot keep pace with new services being marketed and the specialized pricing associated with such new services, a system and method are provided that generate a billing augmentation messages that are sent to the billing entity and that cause an incremental increase of a bill for the handling of a particular message type. The incremental increase is equivalent to a charge that the billing system is already configured to bill. In a preferred embodiment of the invention, the message is an electronic message such as an SMS message and the billing augmentation messages are generated by and sent from an intercarrier vendor.
    Type: Application
    Filed: May 4, 2004
    Publication date: September 29, 2005
    Inventors: Derek Tam, Robert Lovell
  • Publication number: 20050201392
    Abstract: A system for enabling exchange of content over a communications network is disclosed having a first category of users comprising wireless carriers and a second category of users comprising content providers. A content gateway platform is provided having a database for storage of content. The content providers supply content to the database for use by the wireless carriers and the content is ultimately offered to end-user customers of the wireless carriers.
    Type: Application
    Filed: May 25, 2004
    Publication date: September 15, 2005
    Inventors: Derek Tam, Thilo Rusche, Connor Kyle, Robert Lovell
  • Publication number: 20050197144
    Abstract: A method and system for providing a universal voting card (UVC) is disclosed. Generic votes stored in association with a UVC may be used at any time in any combination against voting campaigns that span, e.g., wireless carrier networks, television networks and television shows. A generic vote is issued by a UVC holder through the dispatch of an SMS message to a destination address (USC, toll-free TN, etc.). Each time that a generic vote is issued by a UVC holder the ‘number of votes remaining’ on the UVC is decremented; when the ‘number of votes remaining’ on the UVC reaches zero then the UVC is no longer usable.
    Type: Application
    Filed: October 29, 2004
    Publication date: September 8, 2005
    Inventors: Derek Tam, Mark Smith, Christian Zimmern, Robert Lovell
  • Publication number: 20050156639
    Abstract: A frequency dividing circuit divides a master clock frequency by a non-integer factor to provide an output clock signal whose frequency is equal to the frequency of the master clock signal divided by that non-integer factor. In one embodiment, the circuit is operative to divide the master clock frequency by 2.5.
    Type: Application
    Filed: March 10, 2005
    Publication date: July 21, 2005
    Applicant: Broadcom Corporation
    Inventors: Ka Lun Choi, Derek Tam
  • Publication number: 20050140451
    Abstract: A programmable gain amplifier with three stages uses fine steps, has a large gain range, and is monotonic. The first stage comprises several amplifiers, each including a resistive feedback loop. The feedback loop comprises a series of resistors, with each resistor acting as a tap. Since the number of resistors in the loop is unchanging, monotonicity and stability is guaranteed when resistance is increased using successive taps. A switch system connects two taps at a time to an interpolation stage. Each of these taps corresponds to a specific resistor level, and thus a gain level. The interpolation stage uses a plurality of current sources inside a feedback amplifier to control the interpolation, in order to provide fine gain steps.
    Type: Application
    Filed: December 24, 2003
    Publication date: June 30, 2005
    Inventors: Derek Tam, Ardie Venes
  • Publication number: 20050108334
    Abstract: System and methods for providing multimedia message service (MMS) interoperability between an initiating carrier and a destination carrier. A transcoding facility receives an MMS message from an initiating carrier and accesses a number portability database to determine an identity of a destination carrier to which the MMS message is intended to be sent and a carrier profile repository to obtain a carrier profile for the destination carrier, the carrier profile including information regarding an MMS format acceptable to the destination carrier.
    Type: Application
    Filed: November 14, 2003
    Publication date: May 19, 2005
    Inventors: Derek Tam, James Farrow, William Duddley, Thilo Rusche, Brian Beggerly, Robert Lovell
  • Publication number: 20050093588
    Abstract: Methods and systems for fully differential frequency doubling include receiving a differential input signal having a first frequency, generating a non-inverted or positive output signal having twice the frequency of the input signal, and generating an inverted or negative version of the positive output signal. The positive and negative output signals form a fully differential output. The duty ratio of the output signals substantially matches a duty ratio of the input signals. Fully differential frequency doubling can be implemented with NMOS and/or PMOS devices. The invention further provides optional circuitry for increasing an output signal level.
    Type: Application
    Filed: April 5, 2004
    Publication date: May 5, 2005
    Inventors: Derek Tam, Venugopal Gopinathan
  • Publication number: 20050087839
    Abstract: A circuit with dielectric thicknesses is presented that includes a low-pass filter including one or more semiconductor devices having a thick gate oxide layer, while further semiconductor devices of the circuit have thin gate oxide layers. The low-pass filter semiconductor device includes an N-type substrate, a P-type region formed on the N-type substrate, a thick gate oxide layer formed over the P-type region, a P+ gate electrode formed over the thick gate oxide layer and coupled to a first voltage supply line, and P+ pick-up terminals formed in the P-type region adjacent the gate electrode and coupled to a second voltage supply line. The low-pass filter semiconductor device acts as a capacitor, whereby a gate-to-substrate voltage is maintained at less than zero volts to maintain a stable control voltage for the circuit.
    Type: Application
    Filed: October 28, 2004
    Publication date: April 28, 2005
    Inventors: Derek Tam, Jasmine Cheng, Jungwoo Song, Takayuki Hayashi
  • Patent number: 6882189
    Abstract: A programmable divider includes a synchronous counter configured to process an input clock signal and produce first output signals in response the input clock signal. A number of logic devices are coupled to the synchronous counter and configurable to receive the first output signals and correspondingly produce second output signals. Also included is a multiplexer that is configured to receive the second output signals and has an output coupled to an input of the synchronous counter. In the programmable divider, characteristics of the synchronous counter are selectable based upon a particular number of the logic devices configured.
    Type: Grant
    Filed: October 14, 2003
    Date of Patent: April 19, 2005
    Assignee: Broadcom Corporation
    Inventors: Derek Tam, Takayuki Hayashi
  • Publication number: 20050035794
    Abstract: A programmable divider includes a synchronous counter configured to process an input clock signal and produce first output signals in response the input clock signal. A number of logic devices are coupled to the synchronous counter and configurable to receive the first output signals and correspondingly produce second output signals. Also included is a multiplexer that is configured to receive the second output signals and has an output coupled to an input of the synchronous counter. In the programmable divider, characteristics of the synchronous counter are selectable based upon a particular number of the logic devices configured.
    Type: Application
    Filed: September 22, 2004
    Publication date: February 17, 2005
    Inventors: Derek Tam, Takayuki Hayashi
  • Patent number: 6828654
    Abstract: In a low-pass filter for a phase locked loop (PLL) circuit, a capacitor formed by an N-type substrate, a P-type region formed on the N-type substrate, a thick oxide formed over the P-type region, a P+ gate electrode formed over the thick oxide and coupled to a first voltage supply line, and P+ pick-up terminals formed in the P-type region adjacent the gate electrode and coupled to a second voltage supply line, whereby a gate-to-substrate voltage is maintained at less than zero volts to maintain a stable control voltage for the PLL.
    Type: Grant
    Filed: December 27, 2001
    Date of Patent: December 7, 2004
    Assignee: Broadcom Corporation
    Inventors: Derek Tam, Jasmine Cheng, Jungwoo Song, Takayuki Hayashi
  • Publication number: 20040075475
    Abstract: A programmable divider includes a synchronous counter configured to process an input clock signal and produce first output signals in response the input clock signal. A number of logic devices are coupled to the synchronous counter and configurable to receive the first output signals and correspondingly produce second output signals. Also included is a multiplexer that is configured to receive the second output signals and has an output coupled to an input of the synchronous counter. In the programmable divider, characteristics of the synchronous counter are selectable based upon a particular number of the logic devices configured.
    Type: Application
    Filed: October 14, 2003
    Publication date: April 22, 2004
    Applicant: Broadcom Corporation
    Inventors: Derek Tam, Takayuki Hayashi