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A predistortion apparatus and predistortion method

A pre-distortion and equipment technology, applied in the direction of reducing distortion to improve control circuits, improving amplifiers to reduce nonlinear distortion, electrical components, etc. question

Inactive Publication Date: 2010-07-07
FUJITSU LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Out-of-band radiated power degrades the characteristics of another system using an out-of-band frequency
[0007] Furthermore, although being Figure 11 The signal characteristics in 1102 are masked, but the unwanted spectrum is also radiated into the signal frequency band 1102
This results in the degradation of the characteristics of the signal itself
[0008] In addition, since many current digital modulation systems require linear amplifier characteristics, when using an amplifier with the aforementioned saturation characteristics, it is unavoidable to use a linear low input power section
This results in a degradation of transmit amplifier power efficiency

Method used

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  • A predistortion apparatus and predistortion method
  • A predistortion apparatus and predistortion method
  • A predistortion apparatus and predistortion method

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Embodiment Construction

[0042]Hereinafter, one embodiment of a distortion compensation device to be disclosed will be described in detail with reference to the accompanying drawings. Note that the functions of the predistortion unit and the like of the disclosed distortion compensation device are provided by installing a DSP (Digital Signal Processor).

[0043] as a way to enhance Figure 12 A system of distortion compensation capabilities for conventional power series type predistortion systems is shown, providing a predistortion system using multiple power series.

[0044] Since the disclosed embodiments assume a predistortion system using multiple power series, the basic structure will be described first.

[0045] figure 1 It is a structural diagram of a distortion compensating device for a plurality of power series predistortion systems.

[0046] A plurality of predistortion units (PD units) 101#1 to 101#N constituted by power series calculations are prepared, and each PD unit performs differ...

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Abstract

The invention provides a predistortion apparatus and predistortion method. The predistortion apparatus for compensating for a distortion arising from a non linear property in input to output characteristics of an amplifier, by processing calculation of a plurality of coefficients for a plurality of power series defining the predistortion characteristics for a plurality of power ranges, respectively, the predistortion apparatus includes: a coefficient update unit for setting and updating coefficients of the power series to provide the predistortion characteristics for the plurality of power ranges in accordance with a comparison between the input and output of the amplifier; and a determination unit for determining at least one threshold value defining the plurality of power ranges by shifting the threshold value and operating the coefficient update unit for updating the coefficients for each of the power series corresponding to each of the power ranges defined by the shifted thresholdvalue.

Description

technical field [0001] Certain aspects of the embodiments discussed herein relate to a technique for a predistortion system that compensates for distortion caused by non-linear characteristics of an amplifier from input to output characteristics. Background technique [0002] Generally, high-efficiency transmission amplifiers used in wireless transmission devices such as mobile base stations have strong nonlinear characteristics. Therefore, when transmitting a high-speed wireless communication modulation signal, such nonlinear distortion in the transmission amplifier causes out-of-band radiation power of the transmission modulation signal, and adjacent transmission channels are affected. [0003] As a system for limiting out-of-band radiation caused by a transmission amplifier, there is known a predistortion system by adding a distortion signal having a characteristic opposite to the nonlinear distortion characteristic of a transmission amplifier to an input signal and input...

Claims

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Application Information

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IPC IPC(8): H03G1/04
CPCH03F1/3247H04B1/04H03F1/32H04L27/20
Inventor 滨田一石川广吉宇都宫裕一长谷和男札场伸和石川颂平
Owner FUJITSU LTD