US 7,248,112 B2Granted

Hybrid distortion compensation method and hybrid distortion compensation device

AssigneeMatsushita Electric Industrial Co., Ltd.

InventorHiroshi Itahara

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Abstract

A hybrid distortion compensation method and apparatus that greatly improves the capability to compensate for non-linear distortion due to a high frequency power amplifier over a wideband in strict conditions of smaller size and reduced power consumption. An adaptive pre-distortion section (14) and a feed forward distortion compensation circuit (30) are connected via a D/A converter (20), an A/D converter (28) and the like, and signals of parts of the feed forward distortion compensation circuit (30) are taken out using a switch circuit (SW), fed back to a digital signal processing system, and processed using highly accurate digital signal processing in a control-monitoring section (60). After an adjustment section (51) makes characteristics of two input signals of the feed forward distortion compensation circuit (30) coincide, feed forward distortion compensation is performed. A sequencer (80) controls the components sequentially.

Claims11

Dependent claims

A hybrid distortion compensation method of digital control using both pre-distortion processing of a digital signal and distortion canceling processing of a feed forward scheme, said method comprising:

a first step of performing pre-distortion processing on an input digital signal by a pre-distortion circuit, converting the pre-distortion processed digital signal into an analog signal, amplifying the converted analog signal by a power amplifier, converting the amplified signal into a digital signal, and adaptively controlling a pre-distortion characteristic of said pre-distortion circuit based on the converted digital signal;
a second step of converting each of the output signal of said power amplifier input to a main path of a circuit that performs said distortion canceling processing of the feed forward scheme and a reference signal input to a feed forward loop into a digital signal, measuring characteristics of each converted signal by using digital signal processing, and adjusting at least one of gain, phase, and delay of said reference signal based on the measuring results such that the characteristics of said converted signals are the same;
a third step of converting a signal of said feed forward loop in said circuit that performs the distortion canceling processing of the feed forward scheme into a digital signal, detecting a correlation between the digital signal and said reference signal to measure a leakage amount of the reference signal contained in said signal of the feed forward loop, and determining the adjusting result of the second step;
and
a fourth step of converting the output signal of said circuit that performs the distortion canceling processing of the feed forward scheme into a digital signal, and monitoring whether a predetermined characteristic of the converted digital signal is within a permissible range by using digital signal processing.

2 more elements

A hybrid distortion compensation apparatus of a digital control scheme, comprising:

a high frequency power amplifier;
a pre-distortion section that gives a characteristic opposite to a non-linear characteristic of the high frequency power amplifier, to an input digital signal;
a first signal path that comprises a first D/A converter for transmitting an output signal of the pre-distortion section to the high frequency power amplifier;
a feed forward distortion compensation circuit that performs feed forward distortion compensation on the output signal of the high frequency power amplifier;
an adjuster that adjusts a characteristic of the input digital signal not going through the pre-distortion section;
a second signal path that comprises a second D/A converter for transmitting an output signal of the adjuster as a reference signal of feed forward distortion compensation to the feed forward distortion compensation circuit;
a switch circuit that selectively takes out one of the output signal of the high frequency power amplifier given to the feed forward distortion compensation circuit, the reference signal given to the feed forward distortion compensation circuit via the second signal path, the signal of feed forward loop of the feed forward distortion compensation circuit and the output signal of the feed forward distortion compensation circuit;
a third signal path comprising an A/D converter for feeding back the signal outputted from the switch circuit to the pre-distortion section side;
a control section that measures a characteristic of each of the output signal of the high frequency power amplifier and the reference signal, which are fed back via the third signal path, adjusts a characteristic of the input digital signal by adaptively changing a characteristic of the adjuster based on the measurement results so that characteristic of both the signals become, the same, and, after the adjustment is completed, outputs a signal indicating adjustment completion;
a monitoring section that measures a characteristic of the output signal of the feed forward distortion compensation circuit fed back via the third signal path, determines whether the distortion compensation is good or not based on the measurement result, and outputs a signal indicating the determination result;
and
a sequencer that receives the signal indicating adjustment completion outputted from the control section and the signal indicating the determination result outputted from the monitoring section, switches the switch circuit based on the received signals, and gives a signal indicating a switching state of the switch circuit, as a signal for sequentially controlling operations of the control section and the monitoring section, to the control section and the monitoring section.

9 more elements

Dependencies are inferred from the claim text.