Chapter 4: Field-Programmable and Reconfigurable Analogue and Mixed-Signal Arrays


Yichuang Sun, Rushikesh Lala

4.1 Introduction

The trend in modern VLSI circuit design is to increase the level of integration, decrease the time of design and development, and reduce the cost of products. The key concept for this is to use a single hardware implementation for more than one type of system by reprogramming it for different systems in the field; this type of reconfigurability can be achieved by programmability. The need for programmability and reconfigurability has led to the use of field-programmable arrays. The advantages of these are fast prototyping, on-the-fly reconfiguration, use of PC-based design tools and reduced level of expert knowledge required to build working ICs.

Electronic and communications systems contain both analogue and digital circuits. Programmability can be easily achieved for digital circuits using field programmable gate arrays (FPGA). The FPGA technique has been very well established. To make a whole system fully programmable and reconfigurable, the analogue part must also be programmable. Also, expensive and time-consuming analogue design needs to be automated to shorten the product-to-market cycle. This has resulted in the emergence of field-programmable analogue arrays (FPAA) [1–25]. The field-programmable mixed-signal array (FPMA) is also emerging [26], as is the system on a programmable chip (SoPC) [27].

Analogue signal processing [28–36] is normally preferred in high-speed and lowpower applications. For many signal-processing applications, analogue ICs require a smaller chip area and have lower power consumption than their digital counterparts, mainly due to the lack of requirements for anti-aliasing and post-smoothing filters and A/D and D/A signal converters. For these reasons, analogue circuitry is advantageous for wireless and portable applications where compactness and low-power consumption are important. Also, analogue signal processing circuits can work at much higher frequencies than digital equivalents, and thus in high bandwidth applications such as wireless communication transceivers and computer hard disk read/write channels, analogue circuits have been widely used. FPAAs, which offer rapid prototyping on a single IC, are proving to be a very useful tool for the design of working analogue and mixed-signal ICs. In many cases, the complexity of digital circuit design can also be reduced by using programmable analogue arrays for the analogue part in the system [2].

As is generally the case for analogue against digital design, there are fundamental difficulties in realising universal FPAAs over FPGAs. Apart from those well-known challenges such as linearity, noise and band width subject to process and environmental variations, the configurable analogue blocks in the FPAA must provide a number of programmable functions and the configurable routing should not decrease the accuracy of the implemented circuit. Research into FPAAs and applications has attracted substantial interest across the whole IC sector including both academia and industry. Several FPAA products have been commercially available from companies [21–25] for research, development and teaching uses and continued activities in the field are also actively being conducted.

This chapter overviews FPAA. General concepts, architectures, design issues, circuit techniques and applications of FPAAs are presented. Commercial FPAAs are reviewed and a CMOS OTA-C FPAA is described. The concepts of FPMA and systems on a programmable chip are also introduced. Potential applications of FPAAs and FPMAs in wireless communications are discussed. The chapter is organised in the following way. Section 4.2 is concerned with generic concepts, architectures, design issues, advanced circuit techniques, and general applications of FPAAs. Section 4.3 overviews commercial FPAA products with different bandwidths and circuit techniques. The design and implementation of a continuous-time high-frequency CMOS OTA-C FPAA is then presented in Section 4.4. Section 4.5 introduces the concepts of FPMA and systems on a programmable chip (SoPC). Potential applications of FPAA and FPMA in universal transceivers are described in Section 4.6. Finally, Section 4.7 concludes the chapter with some future research perspectives of the FPAA and FPMA.




Wireless Communication Circuits and Systems
Wireless Communications Circuits and Systems (IEE Circuits, Devices and Systems Series 16)
ISBN: 0852964439
EAN: 2147483647
Year: 2004
Pages: 100
Authors: Yichuang Sun

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