The Elements of Analog Signal Handling

Abstract

Most transducers and laboratory signal sources yield output signals the magnitude of which carries at least a part of the information required in the measurement process. Such signals are called analog signals. It follows that most signal converter systems are required to handle analog signals, at least in the input stages of the converter circuit. One of the most widely used circuit elements for handling analog signals is the amplifier, which, as its name implies, is intended to convert a small signal into a larger one, often to overcome the inconveniently small magnitude of the signal generated by a transducer. Early amplifiers were constructed using thermionic valves, which were physically large and consumed large amounts of power — most of which was wasted as heat. Later amplifiers were constructed using transistors, and many special purpose amplifiers (such as VHF, Very High Frequency, amplifiers) still need to be assembled from a number of these “discrete” devices. However, in the majority of cases amplifiers can be more easily constructed using integrated circuit elements called operational amplifiers (op-amps for short). Op-amps have in fact become the basic ingredient in nearly all aspects of analog signal handling and we shall concentrate our discussion on these devices.