Abstract: An LO leakage canceller for a direct conversion receiver is disclosed. The canceller includes an RF input stage operating to provide at least two input signals, a local oscillator, an in-phase processor, and a quadrature processor. The local oscillator is configured to produce at least two reference signals for modulating the two input signals. Each of the in-phase and quadrature processors includes two consecutive quadrature splitters operating to substantially reduce leakage of the reference signal from the local oscillator to the RF input stage.

Abstract: Transmitter architectures for a communications system having improved performance over conventional transmitter architectures. The improvements include a combination of the following: faster response time for the control signals, improved linearity, reduced interference, reduced power consumption, lower circuit complexity, and lower costs. For a cellular application, these improvements can lead to increased system capacity, smaller telephone size, increased talk and standby times, and greater acceptance of the product. Circuitry is provided to speed up the response time of a control signal. The control loop for various elements in the transmit signal path are integrated. A gain control mechanism allows for accurate adjustment of the output transmit power level. Control mechanisms are provided to power down the power amplifier, or the entire transmit signal path, when not needed.

Abstract: A wireless communication with a receiver subsystem capable of supporting communications operating on two or three distinct frequency bands while incorporating only one or two oscillating devices, respectively. For example, such a subsystem could be integrated in a wireless communication hand-held device configured to operate within three frequency ranges in order to support Cellular, PCS, and GPS services. The receiver subsystem includes a receiver subsystem front end configured to receive first, second, and third receive signals operating under three different frequency bands. The three receive signals are subjected to front-stage filtering, low-noise amplifier, and bandpass filtering in order to remove any unwanted radio frequency components. The first signal is subsequently down-converted into an IF signal by mixing it with a first reference signal generated by a first voltage controlled oscillator (VCO).

Abstract: A power amplifier circuit arrangement including a power amplifier, and a bypass network for bypassing an RF-input signal around the power amplifier when excess gain and output power are not needed. When the bypass network is used, the power amplifier is turned off. A circulator connects the bypass network to the power amplifier output, thus removing the requirement of an output switch. The RF-input signal enters the circulator which routes the signal toward the output of the power amplifier. Because the amplifier is off, its output appears as a high impedance and reflects the signal back to the circulator. The circulator routes the reflected signal the signal output.