Abstract: An apparatus and method linearize a power amplifier in a transmitter by using a dual time alignment scheme. A first adjustable time delay unit delays a modulator signal input of a power amplifier. A first time delay estimator estimates a time delay between the delayed feedback signal and the reference signal, and adjusts the first adjustable time delay unit based on the estimated time delay between the delayed feedback signal and the reference signal. A second adjustable time delay unit delays the feedback signal. And a second time delay estimator estimates the time delay between the delayed feedback signal and the reference signal, and adjusts the second adjustable time delay unit based on the estimated time delay between the delayed feedback signal and the reference signal.

Abstract: A device and a method for crest factor reduction reduces peak-to-average ratio (PAR) to increase power amplifier efficiency. A first hard clipping block performs hard clipping on an input signal when the amplitude of the input signal is greater than a first threshold. A shaping filter reshapes the spectrum of the hard clipped signal. An interpolator increases the sampling rate of the reshaped signal. A second hard clipping block performs hard clipping on the interpolated signal when the amplitude of the interpolated signal is greater than a second threshold.

Abstract: An apparatus and method linearize a power amplifier in a transmitter by using a dual time alignment scheme. A first adjustable time delay unit delays a modulator signal input of a power amplifier. A first time delay estimator estimates a time delay between the delayed feedback signal and the reference signal, and adjusts the first adjustable time delay unit based on the estimated time delay between the delayed feedback signal and the reference signal. A second adjustable time delay unit delays the feedback signal. And a second time delay estimator estimates the time delay between the delayed feedback signal and the reference signal, and adjusts the second adjustable time delay unit based on the estimated time delay between the delayed feedback signal and the reference signal.

Abstract: A device and a method for crest factor reduction reduces peak-to-average ratio (PAR) to increase power amplifier efficiency. A first hard clipping block performs hard clipping on an input signal when the amplitude of the input signal is greater than a first threshold. A shaping filter reshapes the spectrum of the hard clipped signal. An interpolator increases the sampling rate of the reshaped signal. A second hard clipping block performs hard clipping on the interpolated signal when the amplitude of the interpolated signal is greater than a second threshold.

Abstract: A modem and associated method with both an RS-232 interface and a USB interface connects to a host. The modem detects which of the two interfaces is connected to the host and determines an appropriate data path. For connections to the USB interface, data is routed through a USB processor and over a serial link to the modem processor responsible for modem communications and the transfer of modem data to the POTS. The serial link between the USB processor and the modem processor is used to transfer both modem data and processor communications. A plurality of control lines are used to indicate the type of data being transferred over the serial link. For RS-232 connections, the modem data is transferred to the modem processor. Thus, one modem device may be used for either USB or RS-232 connections.