Abstract: A technique for noise reduction in a wireless communication system uses controllable bandwidth filters (120) to filter a received signal. In a typical implementation, the filters (120) are used at baseband frequencies. A measurement (RSSI) is indicative of the strength of the received signal. A control circuit (144) generates a control signal (146) to control the bandwidth of the filters (120). If the received signal strength is above a first threshold, a wider bandwidth may be used for the filters (120). If the received signal is below a second threshold, the control circuit (144) generates the control signal (146) to set the filters (120) to a more narrow bandwidth. The system (100) may also be used with digital filters (150, 152) following digitization by analog to digital converters (ADCs) (130, 132). The system (100) is particularly well-suited for operation with noise-shaped ADCs (130, 132), such as Delta-Sigma converters.

Abstract: Techniques for controlling operation of control loops in a receiver are described. The operation of at least one control loop is modified in conjunction with a change in operating state, which may correspond to a change in linearity state, gain state, operating frequency, antenna configuration, etc. A change in linearity state may occur when jammers are detected and may cause bias current of analog circuit blocks to be adjusted. The at least one control loop to be modified may include a DC loop, an AGC loop, etc. The operation of a control loop may be modified by disabling the control loop or changing its time constant prior to changing operating state, waiting a predetermined amount of time to allow the receiver to settle, and enabling the control loop or restoring its time constant after waiting the predetermined amount of time.

Abstract: Techniques for operating two receivers to receive data and paging from two systems are described. A primary receiver is associated with better performance than a secondary receiver under poor RF conditions. The two receivers may be operated in either a hybrid mode in which the primary receiver is used to receive paging or a simultaneous mode in which the second receiver is used to receive paging. One of the modes may be selected for use based on RF conditions, received power, demodulation metrics, and/or other criteria. In one design, a mode is selected based on the received power and one or more thresholds. In another design, the hybrid mode is selected for poor RF conditions and, for good RF conditions, the hybrid or simultaneous mode is selected based on received power.

Abstract: A system and method of conducting wireless communications between a wireless communication device (WCD) and both a first network (e.g., IS-2000) supporting voice and data services and a second network (e.g., IS-856) supporting packet data services. The method comprises providing the WCD with a primary transceiver and a secondary receiver for conducting wireless communications in a spatial diversity for the second network traffic or broadcast; disabling the secondary receiver and spatial diversity before a paging slot or 1x system acquisition and synchronization attempts; tuning the secondary receiver to a first network carrier frequency to perform first network activities; and retuning the secondary receiver to a second network carrier frequency for spatial diversity after performing the first network activities. The first network activities may include pilot set maintenance, overhead message maintenance, page match detection, or 1x system acquisition and synchronization attempts.

Abstract: A system and method of improving wireless communications between a wireless communication device and both a first network supporting voice and data services and a second network supporting packet data services. The method comprises providing the WCD with a primary transceiver and a secondary receiver for conducting wireless communications in both a simultaneous-mode and a hybrid-mode; performing simultaneous-mode-to-hybrid-mode and hybrid-mode-to-simultaneous-mode transitions based on a performance metric; and evaluating the performance metric to determine whether to perform the mode transitions. In the simultaneous-mode, the primary transceiver conducts wireless communications in the second network and the secondary receiver conducts wireless communications in the first network. In the hybrid-mode, the primary transceiver use is time multiplexed during all of the first and second networks communications combinations.

Abstract: A technique for noise reduction in a wireless communication system uses controllable bandwidth filters (120) to filter a received signal. In a typical implementation, the filters (120) are used at baseband frequencies. A measurement (RSSI) is indicative of the strength of the received signal. A control circuit (144) generates a control signal (146) to control the bandwidth of the filters (120). If the received signal strength is above a first threshold, a wider bandwidth may be used for the filters (120). If the received signal is below a second threshold, the control circuit (144) generates the control signal (146) to set the filters (120) to a more narrow bandwidth. The system (100) may also be used with digital filters (150, 152) following digitization by analog to digital converters (ADCs) (130, 132). The system (100) is particularly well-suited for operation with noise-shaped ADCs (130, 132), such as Delta-Sigma converters.

Abstract: A tunable SAW resonator circuit is disclosed. The tunable SAW resonator circuit includes a SAW resonator having a Q, a resistor coupled to the SAW resonator to reduce the Q, and a tuning component coupled to the SAW resonator to tune the SAW resonator. A method to tune the SAW resonator is also disclosed. The SAW resonator may be tuned by applying a control signal to the tuning component.

Abstract: A low-power diversity receiver includes at least two receive paths, each of which is designated as a primary or secondary receive path. A primary receive path is compliant with system requirements (e.g., IS-98D requirements). A secondary receive path is not fully compliant with the system requirements and is designed for lower power, less area, and lower cost than the primary receive path. For a multi-antenna receiver, the two receive paths may be used to simultaneously process two received signals from two antennas. For a single-antenna receiver, either the primary or secondary receive path is selected, e.g., depending on whether or not large amplitude “jammers” are detected, to process a single input signal from one antenna. The receiver may include additional receive paths for additional frequency bands and/or GPS.

Abstract: A dynamically programmable RF receiver includes an adjustable bias voltage-controlled oscillator (ABVCO) that operates in both low-interference and high-interference modes. The ABVCO uses a drive current to generate an output signal whose frequency varies based on a control voltage. When a jammer detector detects an interference signal, a state machine adjusts the ABVCO from the low-interference mode to the high-interference mode. Reciprocal mixing between the interference signal and phase noise in the output signal is reduced in the high-interference mode by increasing the drive current to reduce the phase noise. The ABVCO switches to the high-interference mode when a bias control circuit sends a bias control signal to the ABVCO, causing the ABVCO to generate the output signal using a greater amount of drive current. A programmable register contains a control value that determines the magnitude of the bias control signal and ultimately the magnitude of the drive current.