Survey on Field Programmable Analog Array Architectures Eliminating Routing Network

Maha S Diab,Soliman A Mahmoud

doi:10.1109/access.2020.3043292

Abstract

This work focuses on reviewing the field programmable analog array (FPAA) architectures that eliminate the use of switches in signal path. The conventional FPAA architecture is composed of configurable analog blocks (CABs) connected together through switches in routing networks.The architectures covered in this survey have replaced the use of routing network by direct connection between CABs, and use of programmable analog building blocks. The first architecture covered is presented by Becker et al. with a hexagonal topology using operational transconductance amplifier (OTA) as a building block. The second architecture is presented by Mahmoud and Soliman, which uses the second generation current conveyor (CCII+) as a building block for their CABs arranged in a hexagonal architecture as well. Lastly, a more recent FPAA with a rectangular architecture proposed by Diab and Mahmoud is discussed, it uses the OTA as a building block for their rectangular architecture. The three FPAAs targeted continuous-time analog signal processing, having two architectures targeting high frequency applications, while the last targeting low frequency applications. The architectures, CAB structures, and the applications of each FPAA is covered separately in each section.

Highlights

In the field of microelectronics, high level of integration, rapid prototyping, lower product cost, and design time are important traits of modern circuit design
An operational transconductance amplifier (OTA) field programmable analog array (FPAA) architecture using floating gate technology for routing network known as Reconfigurable Analog Signal Processor (RASP) is presented and developed in [20]–[24]
The implementation on the FPAA first realization provided the mapping of two seventh-order band pass filter (BPF) with tunable bandwidth ranging from 0.162 Hz to 101 Hz [43] as shown in Fig. 34, with blue OTAs for the first filter, and the orange OTAs for the second filter, both using a variable gain amplifier (VGA) of the output configurable analog blocks (CABs)

Summary

INTRODUCTION

In the field of microelectronics, high level of integration, rapid prototyping, lower product cost, and design time are important traits of modern circuit design. The middle CAC has its output connected to the neighboring eight CACs. A bi-quad filter was realized using the FPAA with tunable center frequency ranging from 30 kHz to 10MHz. An OTA FPAA architecture using floating gate technology for routing network known as Reconfigurable Analog Signal Processor (RASP) is presented and developed in [20]–[24]. It is reported the design using four CABs achieved a bandwidth of 11 MHz, and dissipated power of 162 mW [28] The need for active analog filter building block, with voltage input and output current, the operation transconductance amplifier (OTA) was chosen for the implementation of filters on the FPAA. Each CAB has 7 Gm-cells, where the middle cell provides first order self-feedback, and there are 6 additional Gm-cells used for input making a total of 55 tunable Gm-cells for the FPAA architecture [8]

APPLICATION

DISCUSSION AND CONCLUSION