Abstract: In general, the disclosure is directed to techniques for combining a high performance receiver and a low power receiver within a wireless communication device (WCD) to reduce power consumption. Upon receiving a signal from a base station, a controller within the WCD detects one or more channel conditions of a radio frequency (RF) environment between the base station and the WCD. The controller selects a high performance receiver to process the received signal when the RF environment is unfavorable and selects a low power receiver to process the received signal when the RF environment is favorable. In this manner, the WCD implements an adaptive receiver that adapts its receiver structure according to RF channel conditions.

Abstract: A phase modulator faithfully reproduces higher frequency modulation using an offset phase-locked loop (OPLL) without passing excessive noise through an increased bandwidth of the OPLL. A quadrature modulator modulates information from a baseband signal onto a passband IF signal and, after a limiter strips away amplitude variations, the OPLL reproduces the phase modulation on an RF signal. The OPLL introduces a group delay that does not vary linearly with the modulation frequency and that consequently causes distortion when uncompensated. A baseband filter filters the amplitude of the baseband signal and introduces a complementary group delay that compensates for the OPLL group delay and results in a combined group delay of the baseband filter, quadrature modulator, limiter and OPLL that remains substantially constant as modulation frequency varies. Compensating for the OPLL group delay reduces distortion and the spectral energy at offset frequencies from the carrier frequency of the RF signal.

Abstract: An embodiment pertains to a phase locked loop (PLL) circuit. The PLL includes a voltage controlled oscillator which outputs a signal at a desired frequency. A phase detector is coupled to an output from the voltage controlled oscillator. The phase detector compares the phase of a signal output from the voltage controlled oscillator (VCO) with the phase of a reference signal. A loop filter is coupled to the VCO and the phase detector. The loop filter has a locking mode of operation for locking the phase of the VCO signal to the phase of the reference signal. The loop filter can subsequently be placed in a tracking mode of operation which adjusts the phase of the VCO signal to track the phase of the reference signal.

Abstract: An adaptive filter suitable for fabrication on an RF integrated circuit and used for transmit (TX) leakage rejection in a wireless full-duplex communication system is described. The adaptive filter includes a summer and an adaptive estimator. The summer receives an input signal having a TX leakage signal and an estimator signal having an estimate of the TX leakage signal, subtracts the estimator signal from the input signal, and provides an output signal having the TX leakage signal attenuated. The adaptive estimator receives the output signal and a reference signal having a version of the transmit signal, estimates the TX leakage signal in the input signal based on the output signal and the reference signal, and provides the estimator signal. The adaptive estimator may utilize an LMS algorithm to minimize a mean square error between the TX leakage signal in the input signal and the TX leakage signal estimate in the estimator signal.

Abstract: This disclosure is directed to techniques for voice and data transmission from a wireless communication device, such as mobile telephone handset. In accordance with the disclosure, a wireless communication provides a hybrid coupler that permits voice and data calls to be combined for transmission over a common air interface. When increased transmit power is required, the wireless communication device prioritizes the voice call over the data call. In this case, the voice call is sent over both the voice output branch and the data output branch, taking advantage of the power amplifier in each output branch chain to achieve a greater overall transmit power for the voice transmission. In this manner, the mobile subscriber unit independently and simultaneously handles data and voice calls under ordinary circumstances, but drops the data call and combines the voice and data output branches for voice transmission when increased transmit power is required for the voice transmission.