| This thesis investigates viable Operational Transconductance Amplifier (OTA) topologies for low voltage applications. With the increase in demand for high data rate services, there has been widespread use of digital systems. However, analog systems still find use since the nature of all signals is analog. Thus every digital signal processing system is made up of both analog and digital sections. The need to lower power consumption in these systems has led to a scaling down of most technologies. This has subsequently made the design of analog circuits further challenging. The need to intelligently implement existing design techniques and further develop newer ones has therefore become very important. This thesis is a step in this direction.; The design of a differential version of an already existing transonductance topology in addition with investigation into techniques such as the use of a negative resistance load (NRL) has been attempted. Furthermore, several other OTAs based on new design techniques have also been investigated. Three of them were implemented using TSMC's (Taiwan Semiconductor Manufacturing Corporation) 0.35μm CMOS process. The results obtained are very exciting. However, there still is room for improvement in terms of power consumption.; In addition, attempts have been made to design low voltage spectral shaping filters that conform to the spectral compatibility requirements for Second Generation High bit-rate Digital Subscriber Line technology (HDSL-2) using Overlapped PAM (Pulse Amplitude Modulation) Transmission with Interlocked Spectra (OPTIS) as the modulation scheme. A 3rd order low pass Butterworth filter using one of the OTAs mentioned above has been implemented in silicon. |
