Abstract: Various embodiments of an audio receiver design for a mobile computing device are described. The mobile computing device may comprise an audio receiver structured and arranged to port to the rear of the mobile computing device. In some embodiments, the mobile computing device may be implemented as a dual-mode Global System for Mobile Communications/Universal Mobile Telephone System (GSM/UMTS) quad-band device. The mobile computing device also may comprise a Global Positioning System (GPS) antenna for providing positioning determination capabilities and location-based services. In various implementations, the audio receiver may be ported to an in-vehicle system, such as an onboard entertainment system, navigation system, and/or communications system. Other embodiments are described and claimed.

Abstract: Various embodiments to reduce radio frequency noise are described. An apparatus may comprise a mobile computing device having a radio frequency noise reduction module to disable a radio frequency noise source in response to a receive active signal from a radio receiver. Other embodiments are described and claimed.

Abstract: Various embodiments to reduce radio frequency noise are described. An apparatus may comprise a mobile computing device having a radio frequency noise reduction module to disable a radio frequency noise source in response to a receive active signal from a radio receiver. Other embodiments are described and claimed.

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.

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.

Abstract: When a power amplifier control loop operates near or in saturation, the quality of the output signal can be degraded and an over current condition can occur. To prevent this, the output signal of the power amplifier is detected, converted to digital, and then converted into the frequency spectrum by means of a Fast Fourier Transform. The spectral characteristics of the output signal are analyzed to determine if the power amplifier control loop is approaching or operating in saturation mode. This determination is made by looking at the power of the output signal at various frequencies. If the output at these frequencies exceeds a threshold value, the power amplifier control loop is approaching saturation. In this situation, the output of the power amplifier can be adjusted to prevent loop saturation. This can be accomplished by reducing the supply voltage to the power amplifier or adjusting the bias voltage.

Abstract: When a power amplifier operates near or in saturation, the quality of the output signal can be degraded and an over current condition can occur. To prevent this, the level of the power supply voltage being provided to the power amplifier must be monitored and controlled. One technique is to provide the supply power to the power amplifier through a pass transistor. By characterizing the resistance of the pass transistor and sensing the voltage drop across the pass transistor, the current being provided to the power amplifier can be determined. If this current is too high, the control input to the pass transistor can be adjusted to limit the current.