A distortion compensating apparatus for compensating for a distortion of a transmission power amplifier. A delay time decision unit calculates the correlation between a transmission signal and a feedback signal fed back from the output side of the transmission power amplifier while varying phase difference between both signals, and decides the total delay time caused in the transmission power amplifier and a feedback loop on the basis of the phase difference in which the correlation is the maximum. A delay unit delays the transmission signal before a distortion compensation processing by the total delay time, and inputs the delayed signal into a distortion compensating apparatus arithmetic unit, which calculates and stores a distortion compensation coefficient on the basis of the transmission signal and the feedback signal fed back from the output side of the transmission power amplifier. A pre-distortion unit applies a distortion compensation processing to the transmission signal by using the distortion compensation coefficient.

Distortion compensating apparatus

A method for calibrating a base station comprising a plurality of antennas is provided First correction information is received from a system module, the correction information determined from first calibration of the base station Signals are received at a radio frequency module from at least one antenna of the base station Second correction information is determined on the basis of the received signals and the first correction information.

Base station calibration

A remote radio head unit (RRU) system for multiple operating frequency bands, multi-channels, driven by a single or more wide band power amplifiers. More specifically, the present invention enables multiple-bands RRU to use fewer power amplifers in order to reduce size and cost of the multi-band RRU. The present invention is based on the method of using duplexers and/or interference cancellation system technique to increase the isolation between the transmitter signal and receiver signal of the RRU.

Remote radio head unit system with wideband power amplifier and method

Apparatus and methods for envelope tracking calibration are provided. In one embodiment, a method of calibrating an envelope tracker having an envelope shaping table generated at a desired gain compression of a power amplifier is provided. The method includes generating a supply voltage for the power amplifier using the envelope tracker, operating the supply voltage of the power amplifier at a first voltage level associated with substantially no gain compression of the power amplifier, and measuring an output power of the power amplifier at the first voltage level. The method further includes decreasing a voltage level of the supply voltage one or more times and measuring the output power at each voltage level, determining a second voltage level of the power amplifier associated with a gain compression equal to about that of the desired gain compression, and calibrating the envelope tracker based on the determination.

Apparatus and methods for envelope tracking calibration

A method for calibrating the output power of a mobile terminal using at least a second order curve fit to describe a power amplifier gain (PAG) setting versus output power characteristic of a power amplifier in a transmitter of the mobile terminal is provided. For each of an upper-band frequency, a mid-band frequency, and a lower-band frequency of a frequency band, multiple measurements of the output power of the mobile terminal are made corresponding to multiple values of the PAG setting, and a curve fit is performed, thereby calculating coefficients defining a polynomial describing the PAG setting versus output power characteristic. Using the polynomials describing the PAG setting versus output power characteristic of the power amplifier for each of the upper-band, mid-band, and lower-band frequencies, values of the PAG setting are determined for each desired output power level for each desired frequency within the frequency band.

N-th order curve fit for power calibration in a mobile terminal

PROBLEM TO BE SOLVED: To provide a power amplification device that simply computes distortion compensation coefficients in a lookup table.SOLUTION: The power amplification device has an amplifier and a distortion compensation section for performing a distortion compensation process of applying beforehand an inverse characteristic of an input-to-output characteristic of the amplifier to a transmission signal, and inputs an output signal of the distortion compensation section into the amplifier to amplify it. The distortion compensation section has: a coefficient storage section storing a series distortion compensation system of distortion compensation coefficients; and a coefficient updating section calculating an error between a signal resulting from the distortion compensation process of a feedback signal of an output signal of the amplifier by using a distortion compensation coefficient read out from the coefficient storage section and the output signal of the distortion compensation section, calculating an update value of the distortion compensation coefficient in the coefficient storage section so as to converge the error, and updating the distortion compensation coefficient in the coefficient storage section with the update value.

Power amplification device, distortion compensation coefficient updating method for the same, and transmission apparatus

PROBLEM TO BE SOLVED: To provide a transmitter and a transmission method that can compensate distortion without the need for increasing bit precision of digital/analog converters(DACs) and eliminate a phase difference caused in the transmitter except for phase distortion by an amplifier. SOLUTION: DACs 31a-31s give a digital input signal converted into an analog signal and a DAC 43 gives a distortion compensation signal converted into an analog signal to an adder 5 respectively. The adder 5 sums both the signals to produce a transmission signal subjected to distortion compensation. An amplifier 8 amplifies this transmission signal and an antenna 9 outputs the amplified signal. On the other hand, an output signal from the amplifier 8 is given to a phase control section A as a feedback signal, where a phase difference between the feedback signal and a reference signal is obtained. A variable demodulation NCO 49 eliminates the phase difference in the feedback signal caused in the transmitter other than the phase distortion by the amplifier on the basis of this phase difference.

Transmitter and transmission method

A quadrature modulator accepts inphase and quadrature signal components, and outputs a signal that is quadrature modulated (212) The quadrature modulator system calculates a first cumulative total based on the inphase component and an inphase component fedback from the output The quadrature modulator calculates a second cumulative total based on the quadrature component and a quadrature component fedback from the output Based on the first and the second cumulative totals, the time difference between the inphase component and the quadrature component is determined The inphase component and the quadrature component are adjusted based on the time difference

Quadrature modulator with compensation of I/Q mismatch

A wireless transmission apparatus includes an amplifier that amplifies power of a multicarrier signal, a first frequency shift unit that performs a first frequency shift on a first signal fed back from the amplifier on the basis of carrier frequencies of the multicarrier signal to output a second signal after the first frequency shift, a band limiting unit that performs frequency band limitation on the second signal to output a third signal after the frequency band limitation, and a distortion compensation device that compensates nonlinear distortion of the amplifier on the basis of the third signal.

Wireless transmission apparatus and distortion compensation method

PROBLEM TO BE SOLVED: To provide a distortion compensation apparatus and a distortion compensation method capable of employing an analog-to-digital converter of which bit accuracy is relatively low and of which operating frequency is also relatively low. SOLUTION: Digital input signals X1, Xq are processed at a modulation/ amplification unit 1 after being multiplied by a distortion compensation coefficient of a distortion compensation coefficient storage unit 33 at a multiplier 31, and are transmitted as an analog output signal Z. On the other hand, the analog output signal Z is fed back, and are provided to a subtractors 35i, 35q after being processed at an attenuator 43, a mixer 41 and an orthogonal demodulator 39 and so on. The subtractors 35i, 35q acquire a difference (error) between the analog input signals X1, Xq and analog fed back signals Y1, Yq, which provided to ADCs 36i, 36q. The ADCs 36i, 36q convert the analog error signals to digital signals which are provided to an extortion compensation coefficient calculation unit 5. The extortion compensation coefficient calculation unit 5 acquires a new extortion compensation coefficient to update the distortion compensation coefficient storage unit 33.

Hiroyoshi Ishikawa

Papers

Power amplification device, distortion compensation coefficient updating method for the same, and transmission apparatus

Transmitter and transmission method

Quadrature modulator with compensation of I/Q mismatch

Wireless transmission apparatus and distortion compensation method

Signal distortion compensation apparatus and signal distortion compensation method