基于循環(huán)平穩(wěn)特性的欠采樣寬帶數(shù)字預(yù)失真研究
doi: 10.11999/JEIT190105
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1.
中國科學(xué)院電子學(xué)研究所 北京 100190
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2.
中國科學(xué)院大學(xué) 北京 100049
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3.
北京郵電大學(xué) 北京 100876
Research of Low Sampling Frequency Broadband Digital Predistortion with Cyclostationary Characteristics
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1.
Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China
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2.
University of Chinese Academy of Sciences, Beijing 100049, China
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3.
Beijing University of Posts and Telecommunications, Beijing 100876, China
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摘要:
為了解決行波管(TWT)寬帶數(shù)字預(yù)失真(DPD)中反饋回路ADC采樣率過高的問題,該文利用信號(hào)的循環(huán)平穩(wěn)特性證實(shí)可通過欠采樣下的輸出信號(hào)估計(jì)功放的非線性模型參數(shù),然后由功放非線性模型參數(shù)和輸入信號(hào)可恢復(fù)出與高采樣率下效果相似的功放輸出信號(hào),最后通過傳統(tǒng)的間接學(xué)習(xí)結(jié)構(gòu)對(duì)功放進(jìn)行數(shù)字預(yù)失真以實(shí)現(xiàn)行波管的線性化。為了驗(yàn)證該方法,利用20 MHz LTE信號(hào)驅(qū)動(dòng)一只55 W的X波段行波管放大器(TWTA)。數(shù)字預(yù)失真反饋回路的ADC采樣率從61.44 Msps降低至6.144 Msps和3.072 Msps,但線性化效果變化不大,表明欠采樣方法是有效的。
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關(guān)鍵詞:
- 行波管放大器 /
- 循環(huán)平穩(wěn) /
- 欠采樣 /
- 數(shù)字預(yù)失真 /
- 線性化
Abstract:In order to reduce the sampling rate of the Traveling Wave Tube (TWT) of the Analog to Digital Converter (ADC) in the feedback loop of Digital PreDistortion (DPD), the nonlinear parameters of the power amplifier model are proved to be estimated with the undersampled output signal based on the cyclostationary of digital modulation signal. The output signal similar to high sampling rate can be obtained by combining the nonlinear parameters of the power amplifier model with the input signal. The DPD of the power amplifier is implemented through indirect learning architecture. To validate the method, a 55 W X-band Traveling Wave Tube Amplifier (TWTA) is driven by a 20 MHz LTE signal. The sampling rate of ADC in the DPD feedback loop is reduced from 61.44 Msps to 6.144 Msps and 3.072 Msps, but the linearization effect has little change, which shows the validation of the undersampling method.
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表 1 不同采樣率下預(yù)失真的鄰近信道功率比
預(yù)失真采樣率(Msps) ACPR-/+20 MHz(dBc) ACPR-/+40 MHz(dBc) 無預(yù)失真 –19.24/–19.94 –37.84/–39.34 61.44 –47.42/–47.78 –49.30/49.00 6.144 –47.07/–47.55 –48.72/–48.15 3.072 –46.87/–46.40 –48.06/–48.40 下載: 導(dǎo)出CSV
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