The IEEE 802.16e-2005 standard, also denoted as mobile WIMAX, was introduced as one of the first real efforts towards the deployment of fourth generation communication systems providing fixed and mobile broadband wireless access. In this paper, we present the studying and sizing of the homodyne receiver, especially the flexible sigma delta analog digital converter intended for use in the WiMAX band from 3.4GHz to 3.6GHz in 5MHz, 7MHz and 10MHz channel bandwidth. Our design technique consists to keep proper ADC architecture in response to multi-mode aspect of WiMAX standard. For this, we set each sampling frequency corresponding to each channel bandwidth so that we will keep the same OSR value for different channel bandwidth. For such specifications, a flexible fourth order continuous-time sigmadelta ADC, with mono-bit quantizer, is presented and its simulation results are shown by using Matlab Simulink.

This paper presents the design of a high performance Regulated Telescopic Operational Transconductance Amplifier (OTA) for low power and high speed sigma-delta modulator for Mobile WiMAX Applications. Indeed, the Regulated Telescopic OTA is an enhanced DC gain Telescopic circuit with the gate voltage of the cascode transistor is controlled by a feedback amplifier. An algorithmic driven methodology is developed ending to the optimal transistor geometries. Moreover, the proposed OTA was post-layout simulated for some process corners, temperature variation and Monte-Carlo analysis. The post-layout simulation results have achieved a DC gain of 66dB, a large GBW of 862MHz with a phase margin of 58degrees with only 6.24mW power consumption. In addition, the use of a robust Bisquare Weights (BW) method is investigated to predict the Regulated Telescopic OTA performance for new generation systems. Then, the impact of Nanometer CMOS on Regulated Telescopic OTA design is highlighted. It shows the potentialities of future CMOS processes to provide high speed and high performance OTA circuit.

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This chapter presents a novel telescopic operational transconductance amplifier (OTA) using the bulk-driven MOS technique. This circuit is optimized for ultra-low power applications such as biomedical devices. The proposed the bulk-driven fully differential telescopic OTA with very low threshold voltages is designed under ±0.9V supply voltage. Thanks to the particle swarm optimization (PSO) algorithm, the circuit achieves high performances. The OTA simulation results present a DC gain of 63.6dB, a GBW of 2.8MHz, a phase margin (PM) of 55.8degrees and an input referred noise of 265.3nV/√Hz for a low bias current of 52nA.

Objective: In this work the design of a fourth-order Reconfigurable Sigma Delta analog-to-digital converter (ΣΔ ADC) for 5MHz, 7MHz or 10MHz channel bandwidths are presented. Materials and methods: Our design technique aims to keep the same ADC architecture in response to multi-band and multi-mode aspects of Mobile WiMAX standard. To this end, we set each sampling frequency corresponding to each channel bandwidth, in order that the same OSR value would be kept for the different channel bandwidths. This technique is intended to optimize the power and area of the ADC that efficiently covers varying channel bandwidths. Moreover, we use the pole placement method to calculate the optimized filter coefficients of Continuous-Time Sigma-Delta (CT ΣΔ) ADC. Results and discussion: Over 5MHz, 7MHz and 10MHz channel bandwidths, the ADC achieved 72.89dB, 67.26dB and 66.47dB peak SNR values, respectively and a dynamic range of 73.5dB, 69.47dB and 66.5dB respectively with only 28mW, 28.2mW and 28.6mW power consumption respectively. Conclusions: The design of the proposed reconfigurable ADC intended for use in the mobile WiMAX standard were achieved. Moreover, the results obtained are satisfactory and are in accordance with theoretical expectations.