The Design and Implementation of Wideband Delta Sigma Modulators for WiMAX
| Autor: | Yao-Tsung Chang, 張耀宗 |
|---|---|
| Rok vydání: | 2007 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 95 WiMAX is a mainly wireless wideband technique for high bandwidth and long distance. The analog-to-digital (A/D) converters play an important role in the system. The over-sampling and noise shaping techniques are applied in analog to digital conversion interface of modern very-large-scaled integrated circuits. Duo to the over-sampling characteristics, delta sigma (ΔΣ) modulators are limited on the application of voice band signals. As the integrated circuits process is improved, it makes many researches transferring to wide-bandwidth applications gradually, such as GSM, WCDMA, Bluetooth, xDSL, and WiMAX. With the progress of wireless communication, A/D converters need higher oversampling ratio and order to achieve the higher speed and resolution in the system, Duo to the requirements of low voltage and low power consumption, the low order delta sigma modulators are not suitable for the high bandwidth system. So, the high order Multibits delta sigma modulator is necessary in the wideband system. The coming products are expected to integrate for less chip area, low cost, and low power consumption. Therefore, the SOC (System on Chip) and low power consumption are the most important concepts in the development for wireless and modern communication systems. In this thesis, we design and impletement Wideband Delta Sigma Modulators for WiMAX. For fitting WiMAX system, the circuit design is a great challenge. Our choice is a delta-sigma ADC, because it has great features for adaptability、programmability, and nonsensitivity to analog components such as the device mismatch and amplifier gain. In addition, it has other advantage of relaxing the requirements of the analog anti-aliasing filters in the AD converters. On the other hand, there is no significant power consumption and noise penalty for the AD conversion of the modulator. Furthermore, the circuit non-idealities effects also can be included in our architectures to predict the final performance of actual the ΔΣ modulators. According to these non-idealities models and analyses, we can obtain the optimum circuit specifications to implement our ΔΣ modulator. In this thesis, Wideband Delta Sigma Modulators for WiMAX is implemented in a standard 0.18-μm 1P6M CMOS technology. The simulation results show that the bandwidth is 10MHz；the sampling frequency is 160MHz；oversampling ratio is 8；the dynamic range and signal to noise distortion ratio are 80 dB and 78 dB |
| Databáze: | Networked Digital Library of Theses & Dissertations |
| Externí odkaz: |
|