Kevin K Chan

US Patent:

6373908, Apr 16, 2002

Filed:

Aug 16, 1999

Appl. No.:

09/375834

Inventors:

Kevin T. Chan - Pasadena CA

Assignee:

Broadcom Corporation - Irvine CA

International Classification:

H04B 110

US Classification:

375346, 375219, 455296

Abstract:

An adaptive electronic transmission signal cancellation circuit for separating transmit data from receive data in a bidirectional communication system operating in full duplex mode is disclosed. The output of a main transmitter responsive to a first bias current is connected to the output of a receiver through an internal resistor. A first replica transmitter responsive to a second bias current and matched to the main transmitter current gain and rise/fall time characteristics is connected to the input terminal of the receiver, and produces a cancellation voltage between the output terminal of the main transmitter and the input terminal of the receiver as a function of the second bias current and the internal resistor. A second replica transmitter matched to the current gain and rise/fall time characteristics of the main transmitter and the first replica transmitter and responsive to the second bias current is connected to the output terminal of the main transmitter for canceling excess current, developed by the first replica transmitter, at the output terminal of the main transmitter.

US Patent:

6389077, May 14, 2002

Filed:

May 9, 2000

Appl. No.:

09/568520

Inventors:

Kevin T. Chan - Pasadena CA

Assignee:

Broadcom Corporation - Irvine CA

International Classification:

H04B 300

US Classification:

375257, 375296, 370208

Abstract:

A power efficient and reduced electromagnetic interference (EMI) emissions transmitter for unshielded twisted pair (UTP) data communication applications. Transmit data is processed by a digital filter. The digital filter output data is converted to a current-mode analog waveform by a digital-to-analog converter (DAC). The digital filter is integrated with the DAC binary decoder in a memory device such as a ROM with time multiplexed output. DAC line driver cells are adaptively configurable to operate in either a class-A or a class-B mode depending on the desired operational modality. A discrete-time analog filter is integrated with the DAC line driver to provide additional EMI emissions suppression. An adaptive electronic transmission signal cancellation circuit separates transmit data from receive data in a bidirectional communication system operating in full duplex mode. For a multi-transmitter system, timing circuitry staggers the time base of each transmitter to reduce the aggregate EMI emissions of the multi-transmitter system.

US Patent:

6411647, Jun 25, 2002

Filed:

Oct 29, 1999

Appl. No.:

09/429887

Inventors:

Kevin T. Chan - Pasadena CA

Assignee:

Broadcom Corporation - Irvine CA

International Classification:

H04L 2700

US Classification:

375216, 375229, 375296, 375350, 708316, 341130

Abstract:

A power efficient and reduced electromagnetic interference (EMI) emissions transmitter for unshielded twisted pair (UTP) data communication applications. Transmit data is interpolated by N and processed by a digital filter to obtain the pulse shape required by the particular communication application. The digital filter output data is converted to a current-mode analog waveform by a digital-to-analog converter (DAC). The digital filter is integrated with the DAC binary decoder in a memory device such as a ROM with time multiplexed output. When implemented in such manner, the logical implementation and memory replaces digital filtering circuits, DAC decoding logic circuit and re-synchronization logic circuits that are conventionally implemented in hardware. Thus, the hardware functionality of these circuits is rendered into arithmetic form and implemented in a memory device.

US Patent:

6538508, Mar 25, 2003

Filed:

Oct 4, 2001

Appl. No.:

09/969793

Inventors:

Yee Ling Cheung - Irvine CA
Kevin T. Chan - Pasadena CA
Siavash Fallahi - Newport Coast CA

Assignee:

Broadcom Corporation - Irvine CA

International Classification:

H03F 136

US Classification:

330 86, 330144, 330282, 330284

Abstract:

A programmable gain amplifier (PGA) has an amplifier and a variable resistor that is connected to the output of the amplifier. The variable resistor includes a resistor that is connected to a reference voltage and multiple parallel taps that tap off the resistor. A two-stage switch network having fine stage switches and coarse stage switches connects the resistor taps to an output node of the PGA. The taps and corresponding fine stage switches are arranged into two or more groups, where each group has n-number of fine stage switches and corresponding taps. One terminal of each fine stage switch is connected to the corresponding resistor tap, and the other terminal is connected to an output terminal for the corresponding group. The coarse stage switches select from among the groups of fine stage switches, and connect to the output of the PGA. During operation, one selected tap is connected to the output of the PGA by closing the appropriate fine stage switch and coarse stage switch, where the selected tap defines a selected group of the fine stage switches.

US Patent:

6594304, Jul 15, 2003

Filed:

Apr 18, 2002

Appl. No.:

10/124967

Inventors:

Kevin T. Chan - Pasadena CA

Assignee:

Broadcom Corporation - Irvine CA

International Classification:

H04B 138

US Classification:

375220, 375222, 375219, 375244

Abstract:

A power efficient and reduced electromagnetic interference (EMI) emissions transmitter for unshielded twisted pair (UTP) data communication applications. Transmit data is processed by a digital filter. The digital filter output data is converted to a current-mode analog waveform by a digital-to-analog converter (DAC). The digital filter is integrated with the DAC binary decoder in a memory device such as a ROM with time multiplexed output. DAC line driver cells are adaptively configurable to operate in either a class-A or a class-B mode depending on the desired operational modality. A discrete-time analog filter is integrated with the DAC line driver to provide additional EMI emissions suppression. An adaptive electronic transmission signal cancellation circuit separates transmit data from receive data in a bidirectional communication system operating in full duplex mode. For a multi-transmitter system, timing circuitry staggers the time base of each transmitter to reduce the aggregate EMI emissions of the multi-transmitter system.

US Patent:

6690742, Feb 10, 2004

Filed:

Mar 5, 2002

Appl. No.:

10/091099

Inventors:

Kevin T. Chan - Pasadena CA

Assignee:

Broadcom Corporation - Irvine CA

International Classification:

H04C 2704

US Classification:

375295

Abstract:

A power efficient and reduced electromagnetic interference (EMI) emissions transmitter for unshielded twisted pair (UTP) data communication applications. Transmit data is processed by a digital filter. The digital filter output data is converted to a current-mode analog waveform by a digital-to-analog converter (DAC). The digital filter is integrated with the DAC binary decoder in a memory device such as a ROM with time multiplexed output. DAC line driver cells are adaptively configurable to operate in either a class-A or a class-B mode depending on the desired operational modality. A discrete-time analog filter is integrated with the DAC line driver to provide additional EMI emissions suppression. An adaptive electronic transmission signal cancellation circuit separates transmit data from receive data in a bidirectional communication system operating in full duplex mode. For a multi-transmitter system, timing circuitry staggers the time base of each transmitter to reduce the aggregate EMI emissions of the multi-transmitter system.

US Patent:

6703865, Mar 9, 2004

Filed:

Oct 26, 2001

Appl. No.:

09/983818

Inventors:

Kevin T. Chan - Pasadena CA

Assignee:

Broadcom Corporation - Irvine CA

International Classification:

H03K 190175

US Classification:

326 82, 326 33

Abstract:

A line driver selectively drives one of two transmission lines. The line driver includes a differential amplifier connected to first and second differential switches. The first differential switch is connected between an output of the differential amplifier and a first of two transmission lines. The second differential switch is connected to the output of the differential amplifier and to the second of two transmission lines. The first and second differential switches are controlled by respective first and second control signals. The output of the differential amplifier is connected to either the first or the second transmission line in response to the first and second control signals. The differential switches include loopback protection to an prevent an incoming signal from passing from one transmission line to another during power down mode.

US Patent:

6744831, Jun 1, 2004

Filed:

Mar 1, 2002

Appl. No.:

10/087239

Inventors:

Kevin T. Chan - Pasadena CA

Assignee:

Broadcom Corporation - Irvine CA

International Classification:

H04B 110

US Classification:

375346, 375219, 375295, 455296

Abstract:

An adaptive electronic transmission signal cancellation circuit for separating transmit data from receive data in a bidirectional communication system operating in full duplex mode is disclosed. The output of a main transmitter responsive to a first bias current is connected to the output of a receiver through an internal resistor. A first replica transmitter responsive to a second bias current and matched to the main transmitter current gain and rise/fall time characteristics is connected to the input terminal of the receiver, and produces a cancellation voltage between the output terminal of the main transmitter and the input terminal of the receiver as a function of the second bias current and the internal resistor. A second replica transmitter matched to the current gain and rise/fall time characteristics of the main transmitter and the first replica transmitter and responsive to the second bias current is connected to the output terminal of the main transmitter for canceling excess current, developed by the first replica transmitter, at the output terminal of the main transmitter.