Designing High-Performance Amplifiers (Analog Circuit Design Series: Volume 3)
Dennis L. Feucht · Institution of Engineering and Technology eBooks · 2010
by inspection, lie at the root of the quest.The sought result is the ability to write down accurate circuit equations by inspection.Circuits can often be analyzed multiple ways.The emphasis of this book is on development of an intuition into how circuits work with a perspective that can be applied more generally to circuits of the same class.The previous two volumes of this Analog Circuit Design series, Designing Amplifi er Circuits and Designing Dynamic Circuit Response, provide the needed concepts for the investigation of fast and precise, or Designing high-performance, amplifi ers as covered in this third volume.Much of the technology appearing here has been derived from the tradition of excellence in engineering found at Tektronix in the development of oscilloscopes and other electronic test and measurement instruments.It begins by considering the parameters of merit by which amplifi er performance can be assessed and then the optimization of stage gain in a multistage amplifi er of limited stage bandwidth.The method of characterizing amplifi er performance in the complex-frequency or s-domain is continued, along with an intuitive method for determining poles of circuits without grinding through too much algebra.Bandwidth extension techniques using inductors is next, including a little-known method originating at Tektronix, applied notably to oscilloscope products by Carl Battjes, Bob Ross, and John Addis, known as T-coil peaking -another marvelous performance enhancer that has yet to become widely known.Some circuits deserve special attention, such as the source follower and shunt-feedback amplifi er.After concentrating on speed, the topics turn toward the other dimension of high performance, that of precision.Noise and distortion are topics as are the circuits of precision, operational amplifi ers (op-amps), and instrumentation amplifi ers.The bipolar junction transistor (BJT) differential pair is given more detailed treatment, as is thermal distortion, a topic that must be considered when setting the static operating point (or bias) of amplifi er circuits.The often used complementary emitter-follower as a power driver output stage is given particularly detailed analysis and simplifi cation so that the various oddities in its response have a simple explanation.After this, speed and precision are combined to produce the highest in amplifi er performance, deserving of a full chapter.It starts with well-known currentinput and current-feedback amplifi ers and then covers another lesser-known topic: composite amplifi ers.These have multiple paths to the output and are Preface ix introduced fi rst in block diagram form and then with some wonderful circuits, many originating at Tektronix.At center stage of these methods are feedforward amplifi ers and Barrie Gilbert's translinear circuits, a conceptual breakthrough during the 1960s.Translinear circuits are simplifi ed by reducing what historically was exponential math to ratios of sums and differences, and hopefully more engineers will venture into their use, for they are "powerful."Buffers receive special treatment, and a variety of other nifty circuits are also presented.Multipliers and programmable-gain amplifi ers (PGAs) end this volume.Much of what is in this book must be credited in part to others from whom I picked up essential ideas about circuits at Tektronix, mainly in the 1970s.I am particularly indebted to Bruce Hofer, a founder of Audio Precision Inc.; Carl Battjes, who founded and taught the Tek Amplifi er Frequency and Transient Response (AFTR) course; Laudie Doubrava, who investigated power supply topics; and Art Metz, for his clever contributions to a number of designs, some extending from the seminal work on translinear circuits by Barrie Gilbert, also at Tek at the same time.Then there is Jim Woo, who, like Battjes, was another oscilloscope vertical amplifi er designer; Ian Getreu and Bob Nordstrom, from whom I learned transistors; and Mike Freiling, an artifi cial