Patent application number | Description | Published |
20110098007 | METHODS AND APPARATUSES FOR TUNING FILTERS - Systems and methods according to the present invention address this need and others by providing filter tuning methods and apparatuses which directly measure filter attenuation by transmitting signaling tones through the filter(s). The measured attenuation is compared with the desired frequency response of the filter. The result of the comparison is used to tune the filter(s). | 04-28-2011 |
20120106600 | ANALOG SIGNAL PROCESSOR FOR NONLINEAR PREDISTORTION OF RADIO-FREQUENCY SIGNALS - RF predistortion apparatus for making linear the output signal of non-linear components such as RF power amplifiers. The apparatus comprises an RF input line for carrying an RF signal connected to an envelop detector for finding the envelop of the RF signal, a power detector for finding the power of the RF signal and a quadrature modulator. The apparatus also comprises a coefficient vector input line for carrying an input signal that carries one or more coefficients to a digitally controlled analog subsystem (DCAS). The DCAS having circuitry for processing both the output of the envelop detector and the output of the power detector by selecting one or more coefficients from the coefficient vector input line for generating a weighted summation of the power of the RF signal and a weighted summation of the envelop voltage of the RF signal that are output to the quadrature modulator. The quadrature modulator has circuitry for mixing the RF input signal with the output of the DCAS to generate a signal for predistorting the RF input signal feeding the power amplifier. | 05-03-2012 |
20130099862 | LINEARIZATION OF BROADBAND POWER AMPLIFIERS - An RF linearizer and an associated method are provided for linearizing a power amplifier. The RF linearizer may include: (a) a quadrature up-converter for up-converting a baseband input signal that is to be transmitted by the power amplifier; (b) an RF analog predistorter controlled by a set of coefficients for predistorting the up-converted input signal; (c) a down-converter for down-converting an output signal of the power amplifier; (d) an error monitor receiving the down-converted output signal and the input signal for providing an error signal; and (e) a signal analyzer receiving the error signal, the signal analyzer using an out-of-band power spectrum of the error signal to optimize the set of coefficients. The input signal may have an in-phase component and a quadrature component. | 04-25-2013 |
20150061762 | DUAL POWER AMPLIFIER LINEARIZER - A circuit in a transmitter with multiple power amplifiers includes multiple individual linearizer circuits each receiving a corresponding input signal and each providing a conditioned input signal to a corresponding power amplifier, The linearizer circuit each include: (a) a pre-distortion circuit receiving (i) the corresponding input signal and (ii) the output signal of a corresponding power amplifier, and providing a pre-distortion signal; (b) a cancelation circuit receiving an interfering signal and providing a cancelation signal; and (c) a combination circuit that combines the cancelation signal and the pre-distortion signal to provide a conditioned input signal to the corresponding power amplifier. | 03-05-2015 |
20150078226 | FILTER ENHANCER AND METHOD - A filter enhancer provides greater performance in a passive filter. The passive filter has an input terminal for receiving a signal in a first frequency band and an output terminal for providing a signal in a second frequency band. The filter enhancer includes: (a) a first canceller circuit coupled between input terminal and output terminal, the first canceller circuit including a first finite impulse response (FIR) filter for attenuating signals in the first frequency band; and (b) a control circuit coupled to output terminal and first canceller circuit for providing adaptive coefficients for configuring the first FIR filter. The first FIR filter may be implemented by either a digital FIR filter or an analog FIR filter. The filter enhancer may further include a second canceller circuit coupled between input terminal and output terminal, the second canceller circuit including a second FIR filter for attenuating signals in the second frequency band. | 03-19-2015 |