Abstract: A method for providing application service is provided. The method discloses that a user is authenticated according to a received application service acquisition request from a user mobile phone, and when the user authentication is passed, the application service acquisition request is sent to an application server, so that the application server provides an application service to the user mobile phone according to the application service acquisition request. The application server does not need to authenticate the user mobile phone by performing an authentication operation on the user mobile phone through a wireless application protocol gateway, thus being capable of reducing the workload of the application server.

Abstract: A method for performing a spline interpolation to up-sample audio data includes up-sampling an input audio signal to generate a first signal having a first frequency. The input audio signal is sampled at an input frequency. The method also includes interpolating data of the first signal to generate a second signal having a second frequency. The data of the first signal is interpolated based on a B-spline interpolation function having at least a fourth order. The method includes down-sampling the second signal to generate an output audio signal having an output frequency. The method further includes updating a time index based on an integer operation that is immune to quantization error for a finite-word length implementation.

Abstract: A method for authenticating the identity of a handset user in a cloud-computing environment is provided. The method includes: obtaining, a login account and a password from the user; judging whether the login account and the password are correct; if the login account or the password is incorrect, refusing the user to access an operating system of the handset; if the login account and the password are correct, sending the login account and the password to a cloud server, wherein the login account and the password correspond to a face sample image library of the user stored on the cloud server; acquiring an input face image of the user; sending the input face image to the cloud server; authenticating, by the cloud server, the identity of the user according to the login account, the password and the input face image.

Abstract: A method for providing application service is provided. The method discloses that a user is authenticated according to a received application service acquisition request from a user mobile phone, and when the user authentication is passed, the application service acquisition request is sent to an application server, so that the application server provides an application service to the user mobile phone according to the application service acquisition request. The application server does not need to authenticate the user mobile phone by performing an authentication operation on the user mobile phone through a wireless application protocol gateway, thus being capable of reducing the workload of the application server.

Abstract: Systems and methods are disclosed to provide automatic power control for a driver circuit. Embodiments disclosed herein enable a driver circuit to automatically decrease the gain of amplified input signals when output power exceeds a threshold. Further, embodiments disclosed herein enable a driver circuit to automatically increase the gain of amplified input signals when battery supply voltage drops to avoid unwanted output signal distortion. By using reference signals for battery power and amplified signal input, the amplifiers of the driver circuit can be automatically adjusted until an equilibrium is reached.

Abstract: A Class-D amplifier arrangement is disclosed that implements an auxiliary feedback loop and a primary feedback loop. The auxiliary feedback loop operates upon an input signal when the Class-D amplifier arrangement is operating under a power-up condition and a power-down condition so that a modulated signal is confined within the auxiliary feedback loop during the power-up condition and the power-down condition. The confinement of the modulated signal within the auxiliary feedback loop during the power-up condition and the power-down condition diverts transient signals coupled onto the modulated signal from an output device. The primary feedback loop operates upon the input signal when the Class-D amplifier arrangement is operating under a normal condition so that the modulated signal is introduced to the output device during the normal condition.

Abstract: Systems and methods are disclosed to provide automatic power control for a driver circuit. Embodiments disclosed herein enable a driver circuit to automatically decrease the gain of amplified input signals when output power exceeds a threshold. Further, embodiments disclosed herein enable a driver circuit to automatically increase the gain of amplified input signals when battery supply voltage drops to avoid unwanted output signal distortion. By using reference signals for battery power and amplified signal input, the amplifiers of the driver circuit can be automatically adjusted until an equilibrium is reached.

Abstract: A Class-D amplifier arrangement is disclosed that implements an auxiliary feedback loop and a primary feedback loop. The auxiliary feedback loop operates upon an input signal when the Class-D amplifier arrangement is operating under a power-up condition and a power-down condition so that a modulated signal is confined within the auxiliary feedback loop during the power-up condition and the power-down condition. The confinement of the modulated signal within the auxiliary feedback loop during the power-up condition and the power-down condition diverts transient signals coupled onto the modulated signal from an output device. The primary feedback loop operates upon the input signal when the Class-D amplifier arrangement is operating under a normal condition so that the modulated signal is introduced to the output device during the normal condition.

Abstract: Disclosed is a switching amplifier having an enhanced supply rejection. The switching amplifier comprises a digital modulator that provides a modulated signal. The switching amplifier further comprises a closed-loop analog driver that is coupled to the digital modulator. As disclosed, the closed-loop analog driver is configured to re-modulate a modulation signal that corresponds to the modulated signal. An output stage of the switching amplifier is driven by the re-modulated signal, thereby providing enhanced supply rejection. In one embodiment, the modulated signal is produced by a digital pulse-width modulator (PWM) circuit of a Class-D amplifier, and has a pulse rate substantially less than a clock rate of the digital PWM circuit. In one embodiment, the switching amplifier is implemented as an audio amplifier in a mobile communication device such as a cellular telephone.

Abstract: Disclosed is a closed-loop class-D amplifier circuit including a modulated reference signal generator that provides a modulated reference signal in a feed-forward path, where the reference signal is modulated corresponding to an input signal. The closed-loop class-D amplifier circuit further includes a comparator to generate a control signal based on a comparison of the modulated reference signal and a correction signal, which in turn is produced by filtering a combination of the input signal and a feedback signal. The closed-loop class-D amplifier circuit also includes a pulse generator to generate a pulse-width-modulated signal to drive an output stage of the closed-loop class-D amplifier based on the control signal.

Abstract: Disclosed is a switching amplifier having an enhanced supply rejection. The switching amplifier comprises a digital modulator that provides a modulated signal. The switching amplifier further comprises a closed-loop analog driver that is coupled to the digital modulator. As disclosed, the closed-loop analog driver is configured to re-modulate a modulation signal that corresponds to the modulated signal. An output stage of the switching amplifier is driven by the re-modulated signal, thereby providing enhanced supply rejection. In one embodiment, the modulated signal is produced by a digital pulse-width modulator (PWM) circuit of a Class-D amplifier, and has a pulse rate substantially less than a clock rate of the digital PWM circuit. In one embodiment, the switching amplifier is implemented as an audio amplifier in a mobile communication device such as a cellular telephone.

Abstract: Disclosed is a closed-loop class-D amplifier circuit including a modulated reference signal generator that provides a modulated reference signal in a feed-forward path, where the reference signal is modulated corresponding to an input signal. The closed-loop class-D amplifier circuit further includes a comparator to generate a control signal based on a comparison of the modulated reference signal and a correction signal, which in turn is produced by filtering a combination of the input signal and a feedback signal. The closed-loop class-D amplifier circuit also includes a pulse generator to generate a pulse-width-modulated signal to drive an output stage of the closed-loop class-D amplifier based on the control signal.

Abstract: In a wireless device, a method and system for a baseband receiver interface including analog and digital components are provided. An analog or a digital interface may be selected for a I/Q data signal received from a front-end receiver. The analog interface may be a conventional RF or a VLIF interface. The I/Q data signal may be digitized when received from the analog interface and saturation detection may be used during digitization of the I/Q data signal. When the analog interface is the VLIF interface, a derotator may be used to remove the VLIF frequency. The derotator may be based on a CORDIC algorithm. The I/Q data signal may be converted from serial to parallel format when received from the digital interface. The received I/Q data signal may be decimated before transferred to a baseband processor.

Abstract: Methods and systems for modulating an input electrical signal are disclosed and may comprise modulating input signals utilizing a digital Class-D modulator and generating a digital output signal that is proportional to the input signals. The digital Class-D modulator may be comprised of four stages. To avoid integrator saturation, the output of at least one integrator stage may be limited by utilizing limiters in integrator feedback loops. The digital Class-D modulator utilizes a pulse width modulation technique. For increased signal to noise ratio (SNR) at a desired output power, the magnitude of a triangular waveform oscillator voltage may be greater than the magnitude of an integrated input signal. The digital output signal may be fed back to an input of at least one of the four stages in the digital Class-D modulator. The triangular waveform oscillator frequency may be adjusted to match desired output frequency.

Abstract: In an audio processing device, a method and system for improved CODEC with polyringer are provided. An audio CODEC may comprise an audio ADC, an audio DAC, and a sidetone generator. Data from an external microphone may be processed by an audio ADC and may be sent to a processor that may be adapted to perform digital signal processing operations. The audio DAC may receive from the processor digital audio and polyphonic ringer data and may process the digital audio and polyphonic ringer data through separate digital filters and digital interpolators. The audio DAC may add the processed digital audio and polyphonic ringer data before analog conversion. The audio DAC may perform analog conversion by utilizing a delta-sigma modulator, a current-based DAC, and a switched-capacitor filter. The converted data may be filtered with an RC filter and may be utilized to drive an external speaker or earpiece.

Abstract: Aspects of a method and system for processing audio signals for handset vibration are provided. In this regard, an electronic device may control vibrations generated by a vibration transducer based on audio signals processed by the electronic device. The vibration transducer may be started and/or stopped based on the audio signal. For example, the vibration transducer may be controlled based on a rhythm and/or tempo of the audio signal and/or a content type of the audio signal. The electronic device may control a pattern and/or a frequency at which the transducer is started and/or stopped based on the audio signal. An intensity of generated vibrations may be varied based on the audio signal. A duration of the generated vibrations may be controlled based on the audio signal. The vibration transducer may be controlled based on an event occurring on the electronic device that triggered the processing of the audio signal.

Abstract: Methods for designing a filterless class-D amplifier and driver are described herein. In the exemplary embodiment, a feedback loop is used to stabilize the filterless class-D amplifier. A pulse width modulated (PWM) output signal is generated by adding a comparator input signal to a comparative signal, and comparing the sum to a peak voltage, which can be a peak value of the comparative signal. A limit of one PWM sample will be generated half per period of the comparative signal, resulting in lower dynamic switching noise and a decreased sensitivity to jitter noise than conventional filterless class-D amplifiers.

Abstract: Methods for designing a filterless class-D amplifier and driver are described herein. In the exemplary embodiment, a feedback loop is used to stabilize the filterless class-D amplifier. A pulse width modulated (PWM) output signal is generated by adding a comparator input signal to a comparative signal, and comparing the sum to a peak voltage, which can be a peak value of the comparative signal. A limit of one PWM sample will be generated half per period of the comparative signal, resulting in lower dynamic switching noise and a decreased sensitivity to jitter noise than conventional filterless class-D amplifiers.

Abstract: Methods and systems for modulating an input electrical signal are disclosed herein. Aspects of the method may comprise modulating analog input signals utilizing a digital Class-D modulator and generating a digital output signal that is proportional to the analog input signals. The digital Class-D modulator may be comprised of four stages. To avoid integrator saturation, the output of at least one integrator stage may be limited by utilizing limiters in integrator feedback loops. The digital Class-D modulator utilizes a pulse width modulation technique. For increased signal to noise ratio (SNR) at a desired output power, the magnitude of a triangular waveform oscillator voltage may be greater than the magnitude of an integrated analog input signal. The digital output signal may be fed back to an input of at least one of the four stages in the digital Class-D modulator. The triangular waveform oscillator frequency may be adjusted to match desired output frequency.

Abstract: The present invention provides systems, methods, and computer program products for performing fractional B-spline interpolation. The fractional B-spline interpolation system includes an upsampling module and a fractional B-spline interpolation filter. The B-spline interpolation filter calculates a set of B-spline interpolation coefficients at a plurality of fine index points using the second derivative of the B-spline base function. The number of B-spline interpolation coefficients in the set is equal to the number of polynomial segments comprising the B-spline base function. For each fine index point, each coefficient in a set of B-spline interpolation coefficients is multiplied by a corresponding original sampling point to generate the value of the interpolated signal at the fine index point. The B-spline interpolation filter also includes a memory for storing a set of initial values needed by the B-spline interpolation filter to calculate the B-spline interpolation coefficients.