Douglas B Roberson

US Patent:

7492217, Feb 17, 2009

Filed:

Nov 12, 2004

Appl. No.:

10/988268

Inventors:

Thomas Holm Hansen - Værløse, DK
Anker Bjørn-Josefsen - Lynge, DK
Lars Risbo - Copenhagen, DK
Douglas A. Roberson - Rockwall TX, US

Assignee:

Texas Instruments Incorporated - Dallas TX

International Classification:

H03F 3/38

US Classification:

330 10, 381 711, 381 945

Abstract:

A multiple-channel audio processor () and an associated plurality of power stages () in an audio system are disclosed. The audio processor () includes a plurality of audio amplifier channels (), each of which includes a pulse-code-modulation (PCM) to pulse-width-modulation (PWM) conversion function (), which generates PWM signals for application to the plurality of power stages (). The audio amplifier channels () each also include an interchannel delay function () for delaying the PWM edges relative to other channels (), for reducing noise. The audio amplifier channels () each also include delay adjust circuitry () for gradually increasing and decreasing the interchannel delay of the channel () on startup and shutdown. This permits a single control terminal (VALID) at the processor to globally enable and disable all of the power stages ().

US Patent:

7797065, Sep 14, 2010

Filed:

May 2, 2005

Appl. No.:

11/119572

Inventors:

David Edward Zaucha - Carrollton TX, US
Venkateswar Reddy Kowkutla - Plano TX, US
Anker Bjørn-Josefsen - Lynge, DK
Lars Risbo - Købernhavn, DK
Douglas Allen Roberson - Rockwall TX, US
Josey George Angilivelil - Sachse TX, US

Assignee:

Texas Instruments Incorporated - Dallas TX

International Classification:

G06F 17/00
H03G 3/00
H03F 3/217

US Classification:

700 94, 381107, 330207 A

Abstract:

A digital audio processor for a digital audio receiver having an improved automute sequence is disclosed. The digital audio processor includes automute detection circuitry that monitors the amplitude of digital audio signals before and after the application of digital filters by digital audio processing circuitry. The amplitude of the input signals are compared against a first threshold level, while the amplitude of the output signals are compared against a second threshold level. In response to the amplitude of the input signals for all of the audio channels falling below the first threshold for a selected time period, a gain stage in each channel ramps down the volume to a mute level, and pulse-width-modulation circuitry is disabled. If the output signal amplitude falls below a second threshold for a channel, the pulse-width-modulation circuitry for that channel is disabled. Hysteresis for the input signal amplitude is preferably added into the automute exit determination.

US Patent:

20060145730, Jul 6, 2006

Filed:

Dec 31, 2004

Appl. No.:

11/026654

Inventors:

Josey Angilivelil - Sachse TX, US
Douglas Roberson - Rockwall TX, US
Stephan Lin - Plano TX, US
Venkateswar Kowkutla - Plano TX, US

International Classification:

H03K 17/00

US Classification:

327099000

Abstract:

A signal processing apparatus includes: (a) A signal treating unit for effecting signal treating functions to present a treated signal at an output. (b) A clock generator receiving a clock signal and using the clock signal for presenting an internal clock signal for use by the signal treating unit. (c) A clock simulating unit occasionally coupled with at least one of the clock signal and the clock generator provides a simulated clock signal generally similar to the internal clock signal when either of the clock signal or the internal clock signal is interrupted. (d) A control unit coupled with the signal treating unit, at least one of the clock signal input locus and the internal clock generator for selectively coupling one of the internal clock signal and the simulated clock signal for use by the signal treating unit.

US Patent:

20060247811, Nov 2, 2006

Filed:

May 2, 2005

Appl. No.:

11/120210

Inventors:

David Zaucha - Carrollton TX, US
Josey Angilivelil - Sachse TX, US
Anker Bjorn-Josefsen - Lynge, DK
Thomas Hansen - Vaerlose, DK
Douglas Roberson - Rockwall TX, US

Assignee:

Texas Instruments Incorporated - Dallas TX

International Classification:

G06F 17/00

US Classification:

700094000

Abstract:

A digital audio-visual receiver () with improved digital control of audio volume is disclosed. Upon receipt of a user volume command, via a front panel () or a remote control and infrared receiver (), sequential logic () in a volume command processor () in a PWM audio processor () of the receiver () initiates a timer (), which measures or counts a selected interval. If additional volume commands are received during the interval, sequential logic () resets and restarts the timer (). Upon the timer () interval elapsing without another volume command, the volume command processor () generates a ramping volume output signal to reach the volume level of the last received volume command over a selected time duration. Audible artifacts during changes in audio volume are thus avoided.

US Patent:

20060251197, Nov 9, 2006

Filed:

May 3, 2005

Appl. No.:

11/120724

Inventors:

David Zaucha - Carrollton TX, US
Douglas Roberson - Rockwall TX, US
Josey Angilivelil - Sachse TX, US
Lars Risbo - Kobernhavn, DK

Assignee:

Texas Instruments Incorporated - Dallas TX

International Classification:

H04B 1/10

US Classification:

375350000

Abstract:

A digital audio processor () is disclosed, in which digital filter coefficients associated with a plurality of sampling frequencies are stored in a plurality of coefficient memory banks (). A controller in the digital audio processor () selects one of the coefficient memory banks () for use in the digital signal processing channels (). In a manual mode, this selection is in response to a manual selection entry in a bank control register (). In an automatic mode, indicated by a specific entry in the bank control register (), sample rate detector circuitry () detects the sampling frequency relative to an external reference, such as a crystal (XTL); the appropriate one of the coefficient memory banks () is then selected based on sampling frequency associations stored in rate select register () in the controller ().

US Patent:

20090116654, May 7, 2009

Filed:

Jan 9, 2009

Appl. No.:

12/351627

Inventors:

Thomas H. Hansen - Vaerloese, DK
Anker Bjoern-Josefsen - Lynge, DK
Lars Risbo - Hvalsoe, DK
Douglas A. Roberson - Rockwall TX, US

Assignee:

TEXAS INSTRUMENTS INCORPORATED - Dallas TX

International Classification:

H04R 5/00

US Classification:

381 28

Abstract:

A multiple-channel audio processor () and an associated plurality of power stages () in an audio system are disclosed. The audio processor () includes a plurality of audio amplifier channels (), each of which includes a pulse-code-modulation (PCM) to pulse-width-modulation (PWM) conversion function (), which generates PWM signals for application to the plurality of power stages (). The audio amplifier channels () each also include an interchannel delay function () for delaying the PWM edges relative to other channels (), for reducing noise. The audio amplifier channels () each also include delay adjust circuitry () for gradually increasing and decreasing the interchannel delay of the channel () on startup and shutdown. This permits a single control terminal (VALID) at the processor to globally enable and disable all of the power stages ().