US 6,639,950 B1 · Method and arrangement for correcting phase error in linearization loop of power amplifier

Abstract

A method and arrangement for correcting a phase error in a linearization loop of a power amplifier, the loop comprising an I/Q modulator (10), one or more delay-causing power amplifiers (13) to be linearized, an I/Q demodulator (11) for generating I and Q feedback signals from the output signals of the amplifier (13), difference means (20, 21) of the I and Q branches for generating I and Q difference signals from the I and Q feedback signals and the I and Q input signals, the I/Q modulator and the I/Q demodulator receiving an oscillator frequency from the same local oscillator (14), and a phase shifter (17), the method comprising determination of a phase error resulting from the delay produced in the linearization loop, which determination comprises feeding excitation signals to the I and Q inputs (I IN, Q_IN) of the linearization loop, measuring the signals resulting from the excitation signals and calculating a phase error by means of the measured signals and excitation signals, and correcting the phase error by adjusting a phase of a local oscillator signal passing to the I/Q modulator or I/Q demodulator by means of a phase shifter (17), whereby on determining the phase error the signals resulting from the excitation signals are measured from the I and Q difference signals or the I and Q input signals of the I/Q modulator (10) and the phase determination is performed while the linearization loop is closed.

Claims11

Dependent claims

A method for correcting a phase error in a linearization loop of a power amplifier, the loop comprising an I/Q modulator, one or more delay-causing power amplifiers to be linearized, an I/Q demodulator for producing I and Q feedback signals from the amplifier output signal, difference means of the I and Q branches for producing I and Q difference signals from the I and Q feedback signals and the I and Q input signals, the I/Q modulator and the I/Q demodulator receiving an oscillator frequency from the same local oscillator, and a phase shifter, the method comprising

determination of a phase error resulting from delay produced in the linearization loop, which determination comprises feeding excitation signals to the I and Q inputs of the linearization loop, measuring the signals resulting from the excitation signals and calculating the phase error by means of the measured signals and excitation signals, and
correcting the phase error by adjusting a phase of a local oscillator signal passing to the I/Q modulator or I/Q demodulator by means of the phase shifter,
characterized in that when determining the phase error, the signals resulting from the excitation signals are measured from the I and Q difference signals or from the I and Q input signals of the I/Q modulator and that
the phase error determination is performed while the linearization loop being closed.

1 more element

A linearization arrangement of a power amplifier, the arrangement comprising

difference means, which form I and Q difference signals out of the actual I and Q input signals and I and Q feedback signals of the linearization loop,
an I/Q modulator, in which the data-containing, baseband I and Q difference signals received from the difference means are combined and modulated to a final frequency,
one or more delay-causing power amplifiers to be linearized by which the final-frequency signal is amplified whereafter it is applied to an antenna to be transmitted,
a sampling arrangement, by which a sample signal is taken from the amplified final-frequency signal prior to the antenna,
an I/Q demodulator, to which said sample signal is applied and in which the sample signal is demodulated to the baseband and the I and Q sample signals forming said I and Q feedback signals are separated therefrom,
a local oscillator, from which a local oscillator signal is applied to the I/Q modulator and I/Q demodulator and
a phase shifter, by which the phase of the local oscillator signal passing to the I/Q modulator or I/Q demodulator is shifted for compensating the phase error of the linearization loop,
the arrangement being arranged to determine the phase error by feeding direct current excitation signals to the I and Q inputs of the difference means of the linearization loop and by measuring the resultant signals, and to calculate the phase error resulting from the delay in the linearization loop by means of the measured signals and the excitation signals, and to correct the determined phase error,
characterized by being arranged to measure the signals resulting from the excitation signals from the I and Q difference signals or the I and Q input signals of the I/Q modulator when determining the phase error,
and by being arranged to determine the phase error while the linearization loop is closed.

7 more elements

Dependencies are inferred from the claim text.

Method and arrangement for correcting phase error in linearization loop of power amplifier

Life of this patent

Method and arrangement for correcting phase error in linearization loop of power amplifier

Life of this patent

Abstract

Claims11