4.7 Conclusions

Several FPAA designs have been published in the past few years. Research in this field is actively going on with great interest from the whole analogue sector and will be a key thrust for future analogue design. This chapter has presented an overview of FPAAs. General aspects of FPAAs have been introduced, which include architectures, CABs, CAD, circuit techniques and applications. Commercial FPAAs were then compared and three products illustrated. Some details of the design and implementation of high-frequency continuous-time OTA-C FPAAs have been presented. We have also mentioned FPMAs and systems on a programmable chip. The potential application of FPAAs and FPMAs in future universal wireless communication systems has been particularly discussed.

Although much research has been conducted and some commercial products have been developed, the work is still in its early stage and much remains to be done. The FPAAs published in the literature or which are commercially available generally have low operating frequency and high power consumption. Some also have limited functions and need external components. FPAAs have been used for quick analogue circuit design in many areas including teaching in higher education institutions. However, there have not been wide applications in communication and information systems.

Lower supply voltage and power consumption, higher frequency operation and larger dynamic range are required for many applications such as wireless communication and computer hard disk systems. Consumer electronic systems also often require very high performance analogue circuits. Low-power and high-frequency CMOS FPAAs will continue to be an active area of development. General-purpose FPAAs will be further developed and the issues of applying application-specific FPAAs embedded in fully reconfigurable electronic systems will have some particular interest. The design of universal transceivers for multistandard mobile communications (GSM, UMTS, etc.) and short-range wireless communications (Bluetooth, WLAN, etc.) using FPAAs will be an attractive topic.

In the past, active simulation of the inductor was utilised due to the difficulty in integrating the passive inductor on silicon. However, active inductor simulation cannot meet the requirements of RF wireless communications and bulky discrete inductors have had to be used in many RF applications. Attempts to put inductors on silicon have thus been more actively pursued recently due to the exploding wireless market [66]. As FPAA's operation frequencies move to RF, CMOS silicon inductors may need to be considered as an elementary component for the CABs. MEMS techniques have also been used to integrate inductors on chips.

Industry has been in the race to make reconfigurable analogue devices for some years and they are now trying to make a reconfigurable mixed-signal device. The latter proves even more difficult and very much effort is needed to make a FPMA with reasonable performance. Implementation of FPMAs is important for SoC and SoPC designs and will be an active subject of future research.