Stephen M Pratt

US Patent:

6356222, Mar 12, 2002

Filed:

May 4, 2000

Appl. No.:

09/564484

Inventors:

Stephen J. Pratt - Cumming GA

Assignee:

Matsushita Mobile Communication Development Corporation of USA - Suwanee GA

International Classification:

H03M 166

US Classification:

341144, 341143

Abstract:

A circuit for increasing the precision of an N-bit digital-to-analog converter. The N-bit digital-to-analog converter includes a digital signal input and an analog signal output. The analog signal output connects to the analog signal input of a translating circuit. The translating circuit includes an analog signal output and a bias enable input. The N-bit digital-to-analog converter receives an N-bit digital signal and converts it into a first analog output signal having 2 possible values over a first voltage range. When the enable input is in an enabled state, the translating circuit translates the first analog output signal into a second analog voltage having 2 possible values over a second voltage range, the second voltage range having a smaller maximum value than maximum value of the first voltage range. When the enable input is in a disabled state, the translating circuit translates the first analog output signal into the second analog voltage having 2 possible values over a third voltage range, the third voltage range having a larger minimum value than the minimum value of the first voltage range. As a result, the full precision range of the N-bit digital-to-analog converter is applied to two voltage ranges within the original voltage range of the N-bit digital-to-analog converter.

US Patent:

6952593, Oct 4, 2005

Filed:

Aug 7, 2001

Appl. No.:

09/923978

Inventors:

Stephen J. Pratt - Cumming GA, US

Assignee:

Matsushita Mobile Communications Development Corporation of U.S.A. - Suwanee GA

International Classification:

H04B001/38

US Classification:

4555521, 455 73, 455 78, 455 86, 4555531

Abstract:

A system and method for using a dual band transceiver to transmit and receive in a first and second band, while reducing the frequency sources. By reducing the number of frequency sources needed to operate a dual band transceiver and using common transmitter and receiver Intermediate Frequencies, the invention also reduces the number of filters and other components needed for its operation. The oscillating signals from these two frequency sources are scaled, combined, mixed, and filtered, such that only two primary frequency sources are needed to operate the front-end and back-end of both the transmitter and receiver of this dual band transceiver.

US Patent:

20050208907, Sep 22, 2005

Filed:

Mar 18, 2004

Appl. No.:

10/803763

Inventors:

Ryo Yamazaki - Suwanee GA, US
William Noellert - Atlanta GA, US
Stephen Pratt - Cumming GA, US

International Classification:

H04B001/04
H01Q011/12
H03F003/217

US Classification:

455126000

Abstract:

Small portable communication devices that support multiple modulation techniques cannot gain the benefits of using an isolator at the output of a power amplifier to provide stability in the load impedance. However, for communication devices that include amplitude modulation schemes, maintaining linear operation of the power amplifier is still required. In the presence of unstable load impedance, this can be a difficult task. As a solution, the linearity of the power amplifier is detected by comparing the envelope of the output signal with the base band signal used to modulate the output signal. If the envelopes are similar, then the power amplifier may be operating in the linear region. When the linearity of the power amplifier degrades, there is an increase in the difference between the envelopes. By adjusting the power level of the input signal to the power amplifier when the envelope difference appears, linearity of the power amplifier is maintained.

US Patent:

20050227646, Oct 13, 2005

Filed:

Mar 18, 2004

Appl. No.:

10/803760

Inventors:

Ryo Yamazaki - Suwanee GA, US
William Noellert - Atlanta GA, US
Stephen Pratt - Cumming GA, US

International Classification:

H04B001/04

US Classification:

455127300, 455115100

Abstract:

Small portable communication devices that support multiple modulation techniques cannot gain the benefits of using an isolator at the output of a power amplifier to provide stability in the load impedance. However, for communication devices that include amplitude modulation schemes, maintaining linear operation of the power amplifier is still required. In the presence of unstable load impedance, this can be a difficult task. As a solution, the linearity of the power amplifier is detected by determining the peak power of the output signal and the average or root-mean-square of a portion of the output signal, such as a mid-amble). The ratio of the peak power and the average power of the output signal are used to determine if the power amplifier is operating in the linear region. If the ratio is too high, then the power amplifier may be operating in the linear region. By adjusting the power level of the input signal to the power amplifier when the ratio increases, linearity of the power amplifier is maintained.