Abstract: Apparatus and methods for providing transmit signals in polar transmitters are described. A modulation signal may be provided from a VCO to low noise and low power signal paths and selectively combined based on a desired output power level. CMOS and CML divider circuits may be used to implement the low noise and low power signal paths respectively, and logic may be provided to select desired signals from the low noise and low power signal stages based on the desired output power level.

Abstract: Apparatus and methods for adjusting spectral characteristics of a polar modulation signal in a polar modulator are described. A detection circuit is configured to determine when an FM signal component of the modulation signal exceeds a threshold value. The output of the detection circuit is coupled with FM and AM mapping circuits to selectively map the FM signal component and an AM signal component of the modulation signal to mapped signals, thereby reducing FM deviation.

Abstract: An apparatus for providing a two point phase/frequency modulation system is disclosed herein. The apparatus includes a first network configured to introduce an offset to center a signal applied to a VCO. The apparatus further includes a second network configured to set a gain of the VCO. A phase tracking network is configured to dynamically adjust the offset and the gain.

Abstract: Linear wideband phase modulation system. Apparatus is provided for linear phase modulation utilizing a phase-locked loop. The apparatus includes a limiting circuit that restricts a range of a modulation signal that is coupled to a voltage controlled oscillator (VCO) associated with the phase-locked loop, and a linearizing circuit that reshapes the modulation signal to improve linearity.

Abstract: System for linear amplitude modulation. Apparatus is provided for linear amplitude modulation of an amplifier. The apparatus includes a processing circuit that receives an amplitude modulation signal and produces one or more amplifier control signals that are coupled to the amplifier. The apparatus also includes a feedback circuit that generates a feedback signal from an output of the amplifier that is input to the processing circuit; and a network that controls a bias of the amplifier in response to the feedback signal to linearize the amplifier's amplitude control.

Abstract: A method of the present invention includes coordinating tuning to the same channel of a radio band wherein the following steps are performed: tuning to a channel, within a radio band, that uses a side band; receiving control information in the side band of the channel; and processing the received audio information in the channel using the control information.

Abstract: Systems for audio and data transmission in a broadcast band are disclosed. The system comprises a channel condition assessment module at the transmit side to identify an un-occupied or empty channel to transmit. The system also comprises a means to achieve automatic channel coordination between the transmit side and the receive side. Further, the transmit side includes a digital interface module and the receive side includes a digital output interface module configured to control an embedding electronic device. Means for enhancing audio privacy and digital data rate are also disclosed.

Abstract: FM radio transmitter is being widely used in portable devices as a convenient way to output audio contents to ubiquitously available FM radio receivers in cars or homes. However, the signal from the FM radio transmitter may be interfering with the signal being broadcast by an FM radio station. A scan system is incorporated into the FM radio transmitter to quickly and reliably identify a vacant channel for the FM radio transmitter to use. The scan system measures on-channel and out-of-channel signal quality and selects a best channel for transmission based on the measured on-channel and out-of-channel signal quality. The scan system is also incorporated into an FM radio receiver to quickly and reliably tune to a valid channel. The scan system selects the valid channel based on the measured on-channel and out-of-channel signal quality.

Abstract: In an embodiment of the present invention, a clock generator circuit is disclosed to include a phase locked loop (PLL) that is responsive to a clock signal quadrature output frequency and a clock signal in-phase output frequency. The clock generator circuit generates a single clock frequency that is a fraction of the frequency of the clock signal quadrature output frequency and the clock signal in-phase output frequency. The PLL includes a single voltage controlled oscillator (VCO) that generates the single clock frequency. A plurality of dividers is included in the clock generator circuit and is responsive to the clock signal quadrature output frequency and the clock signal in-phase output frequency and generates multiple clock frequencies, each clock frequency being a unique frequency, each of the plurality of dividers generating an output that is phase and frequency synchronized to the single clock frequency.