Chip Design of a Low-Voltage Wideband Continuous-Time Sigma-Delta Modulator with DWA Technology for WiMAX Applications
作者机构：Department of Electronic Engineering National Taiwan University of Science and Technology
出 版 物：《Circuits and Systems》 (电路与系统（英文）)
年 卷 期：2011年第2卷第3期
页 码：201-209页
摘 要：This paper presents the design and experimental results of a continuous-time (CT) sigma-delta (ΣΔ) modulator with data-weighted average (DWA) technology for WiMAX applications. The proposed modulator comprises a third-order active RC loop filter, internal quantizer operating at 160 MHz and three DAC circuits. A multi-bit quantizer is used to increase resolution and multi-bit non-return-to-zero (NRZ) DACs are adopted to reduce clock jitter sensitivity. The NRZ DAC circuits with quantizer excess loop delay compensation are set to be half the sampling period of the quantizer for increasing modulator stability. A dynamic element matching (DEM) technique is applied to multi-bit ΣΔ modulators to improve the nonlinearity of the internal DAC. This approach translates the harmonic distortion components of a nonideal DAC in the feedback loop of a ΣΔ modulator to high-frequency components. Capacitor tuning is utilized to overcome loop coefficient shifts due to process variations. The DWA technique is used for reducing DAC noise due to component mismatches. The prototype is implemented in TSMC 0.18 um CMOS process. Experimental results show that the ΣΔ modulator achieves 54-dB dynamic range, 51-dB SNR, and 48-dB SNDR over a 10-MHz signal bandwidth with an oversampling ratio (OSR) of 8, while dissipating 19.8 mW from a 1.2-V supply. Including pads, the chip area is 1.156 mm2.
主 题 词：ADC Analog-to-Digital Conversion Sigma-Delta Modulator ΣΔ DWA
学科分类：080902[080902] 0809[工学-计算机类] 08[工学]
D O I：10.4236/cs.2011.23029
馆 藏 号：203459793...
