Leo H Li

US Patent:

6415001, Jul 2, 2002

Filed:

Dec 1, 1998

Appl. No.:

09/203645

Inventors:

Leo L. Li - Trabuco Canyon CA
William John Domino - Yorba Linda CA
Morten Damgaard - Laguna Hills CA

Assignee:

Conexant Systems, Inc. - Newport Beach CA

International Classification:

H04L 2700

US Classification:

375259, 375316, 375219

Abstract:

A communication system for communicating RF signals at any one of a plurality of communication standards through a common antenna is disclosed. The communication system comprises a transmitting unit, a receiving unit, an IF LO frequency generator, an RF LO frequency generator, a reference source, and an antenna. The transmitting unit has a transmit RF information signal output, a modulator for transforming a transmit baseband information signal into a modulated transmit IF information signal, and an upconverter for upconverting the transmit IF information signal into a transmit RF information signal. The receiving unit has a receive RF information signal input, a first downconverter for downconverting a receive RF information signal to a first receive IF information signal, a second downconverter for downconverting the first receive IF information signal to a second receive IF information signal, an analog-to-digital converter for converting the second receive IF information signal to a receive digital information signal, and a digital signal processor for digitally filtering the receive digital information signal. By selecting expedient IF LOs and RF LOs, the IF LO and RF LO frequency generators can be shared between the transmitting and receiving units, and transmit and receive filters can be shared between different communication standards.

US Patent:

6766178, Jul 20, 2004

Filed:

Aug 31, 1999

Appl. No.:

09/386257

Inventors:

Morten Damgaard - Laguna Hills CA
Leo Li - Trabuco Canyon CA

Assignee:

Skyworks Solutions, Inc. - Irvine CA

International Classification:

H04M 100

US Classification:

4555521, 4555531, 455 76, 455 86, 455216

Abstract:

A multi-band RF architecture including a GSM quadrature modulator for modulating an intermediate frequency (IF) wherein the frequency of the modulated IF signal is changed such that each of the GSM, DCS 1800, and PCS 1900 bands have a respective IF. An intermediate frequency (IF) filter with a pass band that covers the GSM IF, the DCS 1800 IF, and the PCS 1900 IF is connected to the output of the modulator and outputs to a transmit phase lock loop, which translates the IF signal from the IF filter to either a GSM band radio frequency signal, a DCS 1800 band radio frequency signal, or a PCS 1900 band radio frequency signal, depending on the frequency of a local oscillator (LO). The receiver employs a down converter which provides a down converted output signal selected by high side injection for the GSM band an by low side injection for the DCS 1800 and PCS 1900 bands. The down converter outputs to an intermediate frequency (IF) receiver filter centered at 400 MHz designed to pass either the down converted GSM signal, the down converted DCS signal, or the down converted PCS signal to demodulation circuitry. A single phase lock loop circuit is used to supply, on a single output, the LO signal for down converting either the GSM receive band, the DCS 1800 receive band, or the PCS 1900 receive band, as well as the LO for the transmit phase lock loop.

US Patent:

20020068530, Jun 6, 2002

Filed:

Sep 25, 1998

Appl. No.:

09/160646

Inventors:

LEO L. LI - TRABUCO CANYON CA, US

International Classification:

H04B001/44
H04B001/46
H04Q007/20
H04M011/00

US Classification:

455/082000, 455/078000, 455/083000

Abstract:

A communication system for communicating RF signals at a plurality of communication standards through a common antenna is disclosed. The communication system includes a transmitter having transmitter outputs for generating transmit band signals in the transmit bands of each supported communication standard, and a receiver having receiver inputs for receiving receive band signals in the receive bands of each supported communication standard. The communication system also includes a plurality of RF switches. Each RF switch couples either the transmitter output or the receiver input associated with a particular communication standard to the antenna. Whether the communication unit is in transmit mode or receive mode, a harmonic filter coupled between each RF switch and the common antenna filters out harmonics of the transmit band and receive band signals. Each harmonic filter has a passband substantially encompassing the transmit and receive bands of the particular communication standard associated with the coupled RF switch.

US Patent:

20060235805, Oct 19, 2006

Filed:

Apr 13, 2005

Appl. No.:

10/907731

Inventors:

Feng Peng - Huntington Beach CA, US
Leo Li - Trabuco Canyon CA, US
XUJUN LIANG - East Brunswick NJ, US

International Classification:

G06F 17/60

US Classification:

705076000

Abstract:

A universal system with a unique process is presented to validate the authenticity of a merchandise item using the manufacturer's digital signature embedded in a RFID/smart card tag that is mounted with a merchandise item. This system consists of only the tag reader and the tag and doesn't require complicated mounting methods. New process and methods are devised to allow manufacturers to make and deploy the tags with its own digital signature, and enable buyers not only to validate the authenticity of a merchandise item easily and reliably, but also to check the authenticity of the tag reader itself before the first use.

US Patent:

60054433, Dec 21, 1999

Filed:

Mar 19, 1998

Appl. No.:

9/044281

Inventors:

Morten Damgaard - Laguna Hills CA
Leo Li - Trabuco Canyon CA

Assignee:

Conexant Systems, Inc. - Newport Beach CA

International Classification:

H03L 7093
H03L 718
H03L 7185

US Classification:

331 14

Abstract:

A frequency synthesizer for generating two or more output frequency ranges using a Phase Locked Loop (PLL) circuit having a single voltage-controlled oscillator (VCO). In a first embodiment, a frequency multiplier is connected to the output of the VCO. The output of the VCO and the output of the frequency multiplier are selectably fed back, depending upon which output frequency is desired. The output frequency may be taken directly from the VCO or the frequency multiplier. When the output frequency is taken from the output of the frequency multiplier, a control signal adjusts the gain of the phase detector and/or loop filter in order to compensate for the loop gain caused by the frequency multiplier. In a second embodiment, instead of adjusting the phase detector and/or loop filter gain, the values of the N and M dividers are adjusted. In a third embodiment, a frequency multiplier is connected to the output of the VCO and multiplies the output by a predetermined multiplier value.

US Patent:

6150890, Nov 21, 2000

Filed:

Sep 30, 1998

Appl. No.:

9/163798

Inventors:

Morten Damgaard - Laguna Hills CA
Leo L. Li - Trabuco Canyon CA

Assignee:

Conexant Systems, Inc. - Newport Beach CA

International Classification:

H03L 7093
H03L 718
H03L 7185

US Classification:

331 14

Abstract:

Disclosed is a dual band wireless phone, such as a cellular phone for a mobile communications system, with a dual band transmitter that includes a phase-locked loop (PLL). The dual band transmitter includes first and second power amplifiers and the PLL. The first power amplifier has a first input for a first signal at a first radio frequency band, and a first output for an amplified first signal. The second power amplifier has a second input for a second signal at a second radio frequency band and a second output for an amplified second signal. The outputs of the power amplifiers are connectable to an antenna. The PLL generates two output frequency ranges and includes a voltage-controlled oscillator (VCO) which has a first output connected to the first power amplifier and generates a first signal. A frequency multiplier has an input connected to the first output of the VCO and a second output connected to the second power amplifier. The frequency multiplier receives the first signal and generates the second signal.

US Patent:

62088750, Mar 27, 2001

Filed:

Apr 8, 1998

Appl. No.:

9/057124

Inventors:

Morten Damgaard - Laguna Hills CA
Leo Li - Trabuco Canyon CA

Assignee:

Conexant Systems, Inc. - Newport Beach CA

International Classification:

H04B1/40

US Classification:

455552

Abstract:

A dual band RF architecture including a GSM quadrature modulator for modulating an intermediate frequency (IF) wherein the frequency of the modulated IF signal is changed such that one IF is used for the GSM band and another IF is used for the DCS 1800 band. An intermediate frequency (IF) filter with a pass band that covers both the GSM IF and the DCS 1800 IF is connected to the output of the modulator and outputs to a transmit phase lock loop, which translates the IF signal from the IF filter to either a DCS 1800 band radio frequency signal or a GSM band radio frequency signal, depending on the frequency of a local oscillator (LO). The receiver employs a down converter which provides a down converted output signal selected by high side injection for the GSM band an by low side injection for the DCS 1800 band. The down converter outputs to an intermediate frequency (IF) receiver filter centered at 400 MHz designed to pass either the down converted GSM signal or the down converted DCS signal to demodulation circuitry. A single phase lock loop circuit is used to supply, on a single output, the LO signal for down converting either the GSM receive band or the DCS 1800 receive band, as well as the LO for the transmit phase lock loop.

US Patent:

63047489, Oct 16, 2001

Filed:

Sep 23, 1998

Appl. No.:

9/158876

Inventors:

Leo L. Li - Trabuco Canyon CA
Christopher M. Chorey - Newport Beach CA

Assignee:

Conexant Systems, Inc. - Newport Beach CA

International Classification:

H04B 104

US Classification:

455113

Abstract:

A cellular phone for a mobile communications system includes a dual band transmitter which operates at a first radio frequency band and a second radio frequency band. The dual band transmitter includes two amplifiers. The first amplifier has a first input for a first signal at the first radio frequency band, and a first output for an amplified first signal. The first output is connectable to the antenna via a first signal path. The second amplifier has a second input for a second signal at the second radio frequency band and a second output for an amplified second signal. The second output is connectable to the antenna via a second signal path. A filter module is associated with the first and second signal paths and configured to receive a control signal which controls the filter module to have one of a first and second cut-off frequencies.