Delia Rodríguez de Llera González

Automated Receiver Design and Optimization for 4G Wireless Communication Systems

This paper presents the design methodology and underlying algorithms of a tool developed for automated receiver design and optimization for fourth generation (4G) wireless communication systems. An algorithm to systematically design and optimize the receiver budget for the multi-standard case is introduced. The goal of this algorithm is to find a multi-standard receiver budget that meets or exceeds the specs of the addressed wireless standards while keeping the requirements of each of the receiver blocks as relaxed as possible. This tool offers RF engineers a deep insight into the receiver behavior at a very early stage of the design flow. It models the impact of some circuit non-idealities using a high level of abstraction. This reduces the number of design iterations and, thus, the time-to-market of the solution. The reuse of already available intellectual property (IP) blocks is also considered in the tool. This can result in a significant cost, reduction of the receiver implementation

The design of a low-distortion sigma-delta ADC for WLAN standards

A low-distortion sigma-delta analog-to-digital converter (ADC) for wireless local area network (WLAN) standards is presented. The proposed sigma-delta modulator architecture employs the 4-bit 2/sup nd/ order sigma-delta modulator with swing suppression in a 2-2 modified cascaded configuration, which greatly improves the tonal behavior even at 8X over-sampling ratio (OSR). The modulator is designed in 0.18/spl mu/m CMOS process and operates at 1.8V supply voltage. It achieves a dynamic range of 69.1dB and a spurious free dynamic range (SFDR) of 82.2dB for a 10MHz signal bandwidth, and an oversampling ratio of 8.

Tackling 4G challenges with "TACT" - Design and optimization of 4G radio receivers with a transceiver architecture comparison tool (TACT)

Current integration trends imposed by the market are pushing toward the software radio paradigm. 4G radio receivers, where different wireless standards converge, make RF engineers face harder and harder challenges. Electronic design automation (EDA) tools play an increasing role in the design and verification of wireless system. This article presents a transceiver architecture comparison tool (TACT) which is a hierarchical, user-friendly, Matlab-based tool. It automates the design-space exploration procedure for 4G (fourth generation) wireless receivers. An example that considers a multistandard wideband code division multiple access (WCDMA)/wireless local area network (WLAN) receiver was also presented to illustrate the capabilities of TACT

EDA for RF and analog front-ends in the 4G era: Challenges and solutions

Convergence into 4G wireless communication systems pushes the design of radio receivers beyond limits unconceivable only few years ago. The complexity of RF systems has increased enormously as new communication standards have appeared in the wireless scenario. The convergence trends, enabled by the advances in fabrication technology, have driven the software defined radio (SDR) more and more into the RF and analog front-end. There is a clear need for design automation and advanced simulation techniques at the different levels that go from the system idea to chip fabrication. Reducing the number of design iterations between these levels is key in meeting the increasingly tight time-to-market constraints. As of today, there is not a single tool that covers the complete design flow. Instead, there is an intricate puzzle of design and simulation tools that focus on the various steps that go from system to silicon. The amount of RF and analog EDA tools available is certainly scarce in comparison with their digital counterparts. Most of the design work still depends on the radio engineer, making the process less than optimal. This paper describes some of the challenges faced by todays radio designers and discusses some of the solutions provided by the EDA community.

Automated Design of a WCDMA/WLAN Multi-standard Receiver

In this paper we show how TACT, a recently reported radio system design and optimization tool, can be used to optimize the design of a dual mode WCDMA/WLAN receiver. An overview of the underlying frequency planning and receiver budget analysis routines is discussed first. In a case study, a zero-IF WLAN/WCDMA radio receiver is then designed and optimized using the tool. TACT yields optimized design specs for each block in the chain as well as a summary of the system performance obtained. The obtained performance is shown to meet or exceed the requirements of the WCDMA/WLAN standards. As such, the case study validates the benefits of the proposed tool.

A programmable baseband chain for a WCDMA/WLAN (802.11b) multi-standard zero-IF receiver

As we move towards convergent 4G Wireless encompassing both 3G cellular (WCDMA) for wide area networks and Wireless LAN for ”hot-spots”, the development of low power, low cost multi-band multi-standard wireless chipset solutions is a must. To this end this paper presents a programmable architecture for an analog baseband chain intended for use in a zero-IF multi-standard WCDMA/WLAN(802.11b) radio receiver. It also addresses the DC offset cancellation in the baseband chain. This is one of the major impairments in zero-IF receivers whose simplicity makes them suitable for single-chip multi-standard designs but where DC offset can reduce the receiver performance if a proper DC offset cancellation scheme is not devised. System level design of the baseband chain is given leading to design specifications of the different blocks in the chain. Extensive simulations carried out in MATLAB/SimuLink at the system level and in Cadence design tools at the circuit level show the performance of the system. The circuits will be fabricated in a 0.18μm CMOS process for a 1.8 V power supply.