本文關(guān)鍵詞： 過采樣 噪聲整形 Sigma-Delta調(diào)制器 CIC濾波器 半帶濾波器 數(shù)字抽取濾波器　出處：《西安電子科技大學(xué)》2016年碩士論文　論文類型：學(xué)位論文

【摘要】：隨著數(shù)字技術(shù)的不斷進(jìn)步,模數(shù)轉(zhuǎn)換器被廣泛的應(yīng)用在電子技術(shù)的各個方面�，F(xiàn)在非常流行一種叫做Sigma-Delta ADC的低速、高精度ADC,主要應(yīng)用于音頻信號的處理。Sigma-Delta ADC主要由調(diào)制器部分和低通抽取濾波器部分組成,使用了過采樣技術(shù)、噪聲整形技術(shù)和數(shù)字濾波技術(shù)。過采樣和噪聲整形技術(shù)可以將量化噪聲大部分推向高頻范圍,然后再利用低通濾波器將高頻噪聲濾除,從而提高了信號帶內(nèi)的信噪比和精度。在研究了不同類型Sigma-Delta調(diào)制器的基本原理、結(jié)構(gòu)以及實現(xiàn)后,提出總體設(shè)計方案。參數(shù)結(jié)構(gòu)設(shè)定為2-1MASH結(jié)構(gòu)的三階調(diào)制器,1bit量化,過采樣倍數(shù)128倍,實現(xiàn)16bits精度。輸入信號為頻率等于44KHz的正弦信號,采樣頻率為5.632MHz。在MATLAB下的SIMULINK中搭建系統(tǒng)整體架構(gòu),確定具體電路中系數(shù)因子,然后進(jìn)行系統(tǒng)級仿真,仿真可以達(dá)到預(yù)定目標(biāo)并有一定富余量。然后通過Sigma-Delta工具箱展開對電路非理想因素的分析建模,求出了可以獲得較好調(diào)制效果的非理想因素的具體數(shù)值。調(diào)制器后繼續(xù)研究數(shù)字抽濾波器,在分析了抽取的原理后,提出一種多級抽取的實現(xiàn)結(jié)構(gòu)。之后重點研究了兩種性能良好且應(yīng)用廣泛的特殊FIR濾波器:級聯(lián)積分梳狀濾波器以及半帶濾波器。研究了原理、性質(zhì)、實現(xiàn)結(jié)構(gòu)以及優(yōu)點等等。提出了一種多級結(jié)構(gòu)實現(xiàn)128倍抽取的濾波器方案。輸入信號頻率為5.632MHz,經(jīng)過抽取后的輸出頻率為44KHz,通帶波紋小于0.01。首先對梳狀濾波器和半帶濾波器的具體結(jié)構(gòu)參數(shù)、抽取倍數(shù)、階數(shù)做出設(shè)定,并針對梳狀濾波器的特性提出了一種補償濾波器。之后通過在MATLAB中進(jìn)行行為級的建模仿真,驗證了這一結(jié)構(gòu)的合理性。并生成Verilog代碼,在ModelSim中進(jìn)行抽取倍數(shù)的仿真。最后的仿真結(jié)果來看,所設(shè)計的ADC可以達(dá)到信噪比102dB,分辨率16bits的要求。數(shù)字抽取濾波器的輸入頻率5.632MHz,輸出采樣頻率44KHz,通帶頻率20KHz,實現(xiàn)128倍抽取。
[Abstract]:With the development of digital technology, A / D converters are widely used in all aspects of electronic technology. Nowadays, a low speed converter called Sigma-Delta ADC is very popular. High-precision ADC, which is mainly used in audio signal processing. Sigma-Delta ADC is composed of modulator and low-pass decimation filter, and oversampling technique is used. Noise shaping technology and digital filtering technology. Oversampling and noise shaping techniques can push most of the quantized noise to the high frequency range, and then use a low pass filter to filter the high frequency noise. In order to improve the signal-to-noise ratio and precision in the signal band, the basic principle, structure and implementation of different types of Sigma-Delta modulators are studied, and the overall design scheme is proposed. The three-order modulator with a parameter structure of 2-1MASH is quantized by 1bit. The input signal is a sinusoidal signal with a frequency equal to 44kHz, and the sampling frequency is 5.632 MHz. The whole system structure is built in SIMULINK under MATLAB, the coefficient factor in the specific circuit is determined, and the system-level simulation is carried out. The simulation can achieve the predetermined goal and have a certain amount of surplus. Then the non-ideal factors of the circuit are analyzed and modeled by the Sigma-Delta toolbox. The specific values of the non-ideal factors which can obtain better modulation effect are obtained. After the modulator continues to study the digital pumping filter, the principle of the decimation is analyzed. A multistage decimation structure is proposed. Then two special FIR filters with good performance and wide application are studied: cascade integral comb filter and half band filter. In this paper, a multi-level filter with 128-fold decimation is proposed. The input signal frequency is 5.632 MHz, the output frequency is 44KHz, and the passband ripple is less than 0.01.First, the comb filter and semi-filter are compared. The specific structural parameters of the filter, The decimation multiple and order are set, and a compensation filter is proposed according to the characteristics of the comb filter. Then, the rationality of the structure is verified by the behavior level modeling and simulation in MATLAB, and the Verilog code is generated. Finally, the simulation results show that the designed ADC can meet the requirements of SNR 102 dB and resolution 16 bits. The input frequency of digital decimation filter is 5.632 MHz, the output sampling frequency is 44 kHz, the passband frequency is 20 kHz, and the decimation is 128-fold.
【學(xué)位授予單位】：西安電子科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2016
【分類號】：TN761;TN713

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本文編號：1533254