Digital frequency modulation aided ampm predistortion digital transmitter

A pre-compensation and digital transmission technology, applied in the direction of digital transmission system, transmission system, baseband system, etc., can solve problems such as amplitude compression or expansion

Active Publication Date: 2014-05-21
XUESHAN TECH INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Similarly, changing the in-phase data and the quadrature data separately to achieve AMPM predistortion will cause additional compression or expansion of the amplitude, which needs to be corrected by AMAM predistortion

Method used

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  • Digital frequency modulation aided ampm predistortion digital transmitter
  • Digital frequency modulation aided ampm predistortion digital transmitter
  • Digital frequency modulation aided ampm predistortion digital transmitter

Examples

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Embodiment Construction

[0064] The following embodiments and related drawings can fully illustrate the inventive concepts of the present application. Similar element numbers in various figures correspond to similar functions or elements. It should be noted that the term “the present invention” here is used to refer to the inventive concepts presented in these embodiments, but its scope is not limited to these embodiments themselves. In addition, the mathematical expressions in this specification are used to illustrate the principles and logics related to the embodiments of the present invention, and do not limit the scope of the present invention unless otherwise specified. Those of ordinary skill in the technical field to which the present invention pertains can understand that there are various techniques to realize the physical representation forms corresponding to these mathematical formulas.

[0065] figure 2 It is a functional block diagram of a digital transmitter according to an embodiment ...

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Abstract

The invention relates to a digital frequency modulation aided AMPM predistortion digital transmitter. Amplitude-modulation (AM) to AM (AMAM) predistortion data is obtained from an AMAM predistorter. When applied to a digital quadrature signal, the AMAM predistortion data predistorts in-phase (I) and quadrature (Q) data words in a digital quadrature modulator. AM to phase-modulation (AMPM) predistortion data is obtained that is associated with the AMAM predistortion data and a frequency change or a phase shift in a local oscillator (LO) signal is compelled in accordance with the AMPM predistortion data. The frequency-changed or phase-shifted LO signal is provided to a digital upconverter such that an output signal of the digital upconverter is linearized with respect to at least phase distortion in the digital upconverter.

Description

technical field [0001] The present invention is related to predistortion in digital modulators. Background technique [0002] With the development of digital quadrature modulation and direct digital modulation technology, wireless communication systems are increasingly advanced. Wireless communication systems can use RF digital-to-analog converters or multiple current elements in digital power amplifiers to generate output voltages or currents. Mismatch between current elements and intermodulation distortion will affect the amplitude and phase of the output signal of the digital power amplifier. [0003] An example of a modulation constellation shown in FIG. 1(A) is an eight-symbol phase-shift keying (PSK) modulation constellation. Constellation diagram 100 includes a total of eight modulation symbols 120a-120h (collectively symbols 120). Distortion in the digital power amplifier may cause the actual generated symbol 120b' to deviate from its normal state, ie to be differ...

Claims

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Application Information

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IPC IPC(8): H04L25/03H04L27/34
CPCH04L25/03343H04L27/206H04L27/362H04L27/367
Inventor 丹尼斯·马欧尼洪志铭
Owner XUESHAN TECH INC
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