Summary:
This diploma thesis aims at providing a general description of a different type
of amplifier, compared to traditional ones, which is called Current Feedback
Operational Amplifier (CFOA). More specifically, this thesis intends to
explain the fundamental ideas on which the function of CFOAs lays upon
describe the function of CFOAs
present some representative applications on which this CFOA could be used
effectively
This thesis consists of four chapters:
i. In the first chapter current mode circuits are examined in general. An
explanation of the need for introducing and studying these circuits is given
and certain advantages over traditional voltage mode circuit are presented.
ii. In the second chapter, a general amplifier theory is presented and we
suggest an classification system of amplifiers where the CFOAs can find a
position.
iii. In chapter 3, the function of CFOAs is presented in detail. The basic
small signal model of CFOAs is given as well as circuit implementations in
bipolar and CMOS processes. Some 2nd order parasitic phenomena and some issues
related to stability and amplifier noise are also presented. Finally, a
comparison between CFOAs and traditional voltage mode amplifiers is also made.
iv. In the fourth chapter we present some applications of CFOAs as those were
found through searching companies’ datasheets.. We present circuit
implementations of CFOAs
as summing amplifiers
differential amplifiers
IF and RF amplifiers
in active filters circuits
as integrators
as wideband coaxial cable drivers
as AGC amplifier
Keywords:
Current mode circuits , Current Feedback Operational Amplifiers, Αmplifiers classification , Transfer function , Small signal model
