Abstract: A system and method for stabilizing a coefficient set used by a digital predistortion (DPD) engine to apply pre-distortion to a transmit signal and cancel distortion generated by a distorting element or distorting system when transmitting the transmit signal, including obtaining an initial coefficient set; rotating the initial coefficient set to maintain a phase of fundamental components (w10(t), . . . , w1Q(t)) of the initial coefficient set as a constant value; averaging in the time domain the rotated coefficient set to obtain an averaged coefficient set; applying the averaged coefficient set to the DPD engine, the initial coefficient set expressed in a first equation [27]; computing the phase of the fundamental components of the initial coefficient set with a second equation [28]; and computing the rotated coefficient set with a third equation [29].

Abstract: A method and computer program product for operating a linearizer for a circuit, including generating a set of coefficients via a characterizer; predistorting a signal input to the circuit responsive to the coefficients and generating a linearized output in response thereto; filtering the signal through a linear digital filter having linear digital filter taps, each tap other than a first tap being successively delayed by one delay unit; generating powers of the signal; inputting the generated powers of the signal through tapped delay lines, each line having nonlinear digital filter taps, each tap other than a first tap being successively delayed by one delay unit; applying the coefficients to the linear and nonlinear digital filter taps; summing each of the nonlinear digital filter taps corresponding to a certain number of delay units; and adding the sum of each of the delay units to a particular linear digital filter tap.

Abstract: A system and method for stabilizing a coefficient set used by a digital predistortion (DPD) engine to apply pre-distortion to a transmit signal and cancel distortion generated by a distorting element or distorting system when transmitting the transmit signal, including obtaining an initial coefficient set; rotating the initial coefficient set to maintain a phase of fundamental components (w10(t), . . . , w1Q(t)) of the initial coefficient set as a constant value; averaging in the time domain the rotated coefficient set to obtain an averaged coefficient set; applying the averaged coefficient set to the DPD engine, the initial coefficient set expressed in a first equation [27]; computing the phase of the fundamental components of the initial coefficient set with a second equation [28]; and computing the rotated coefficient set with a third equation [29].

Abstract: A method and computer program product for operating a linearizer for a circuit, including generating a set of coefficients via a characterizer; predistorting a signal input to the circuit responsive to the coefficients and generating a linearized output in response thereto; filtering the signal through a linear digital filter having linear digital filter taps, each tap other than a first tap being successively delayed by one delay unit; generating powers of the signal; inputting the generated powers of the signal through tapped delay lines, each line having nonlinear digital filter taps, each tap other than a first tap being successively delayed by one delay unit; applying the coefficients to the linear and nonlinear digital filter taps; summing each of the nonlinear digital filter taps corresponding to a certain number of delay units; and adding the sum of each of the delay units to a particular linear digital filter tap.

Abstract: A system, method and computer program product for stabilizing a coefficient set used by a digital predistortion (DPD) engine to apply pre-distortion to a transmit signal and cancel distortion generated by a distorting element or distorting system when transmitting the transmit signal, including obtaining an initial coefficient set; rotating the initial coefficient set to maintain a phase of fundamental components (w10(t), . . . , w1Q(t)) of the initial coefficient set a constant value; averaging the rotated coefficient set to obtain an averaged coefficient set; and applying the averaged coefficient set to the DPD engine.

Abstract: A linearizer and method. In a most general embodiment, the inventive linearizer includes a characterizer coupled to an input to and an output from said circuit for generating a set of coefficients and a predistortion engine responsive to said coefficients for predistorting a signal input to said circuit such that said circuit generates a linearized output in response thereto. In a specific application, the circuit is a power amplifier into which a series of pulses are sent during an linearizer initialization mode of operation. In a specific implementation, the characterizer analyzes finite impulse responses of the amplifier in response to the initialization pulses and calculates the coefficients for the feedback compensation filter in response thereto. In the preferred embodiment, the impulse responses are averaged with respect to a threshold to provide combined responses. In the illustrative embodiment, the combined responses are Fast Fourier Transformed, reciprocated and then inverse transformed.

Abstract: A system and method for effecting wideband image rejection. In a receiver implementation, the inventive method includes the steps of receiving a first signal in a first frequency band and generating in-phase and quadrature signals therefrom. The phase of the in-phase signal is shifted to provide a second signal and the phase of the quadrature signal is shifted to provide a third signal. A predetermined phase relationship is thereby effected between the second and the third signals. The second and third signals are then summed to provide an output signal which has minimal interference from a mixing signal. In an illustrative receiver application, the phase shifting is achieved via the use of all pass networks. Each of the all pass networks include a differential amplifier having first and second input terminals. The first and the second terminals are connected to a first end of first and second resistive elements, respectively.

Abstract: A system and method for effecting wideband image rejection. In a receiver implementation, the inventive method includes the steps of receiving a first signal in a first frequency band and generating in-phase and quadrature signals therefrom. The phase of the in-phase signal is shifted to provide a second signal and the phase of the quadrature signal is shifted to provide a third signal. A predetermined phase relationship is thereby effected between the second and the third signals. The second and third signals are then summed to provide an output signal which has minimal interference from a mixing signal. In an illustrative receiver application, the phase shifting is achieved via the use of all pass networks. Each of the all pass networks include a differential amplifier having first and second input terminals. The first and the second terminals are connected to a first end of first and second resistive elements, respectively.

Abstract: A transceiver has a digital signal processor which can insert calibration signals of known level and frequency into transmitters for calibration and correction of transmitter parameters. An output of the calibrated and corrected transmitter is subsequently coupled into a calibration mixer along with a mixing signal (e.g., from a local oscillator generator. The outputs of the calibration mixer have known levels and frequencies and are inserted into receivers for calibration and correction of receiver parameters.

Abstract: A "gain control differential pair" (GCDP) conducts current in response to a differential drive signal, with the gain of a signal path formed via the current circuit of one of its transistors controlled by the drive signal. The GCDP is preferably driven with a drive circuit that receives a symmetrical input signal and produces an offset differential drive signal which has the effect of keeping one of the GCDP's transistors turned off over a wider portion of a symmetrical input signal's voltage range, thereby reducing GCDP-caused noise. One or more GCDPs are implemented as part of a Gilbert mixer to regulate the amount of RF current that flows between the mixer's output and input stages, which eliminates the need to provide gain control in other circuits fed by the mixer. When driven with an offset drive signal, the Gilbert mixer simultaneously provides gain control, low distortion, low power consumption and excellent LO/RF isolation.