This book is a monograph, which summarizes the research results of the author in the field of the analysis, design and modelling of small-signal amplifiers and some of their general applications (up to 500MHz), employing various types of monolithic operational amplifiers. In particular, the material in the book covers the following topics and subtopics: - Basic definitions and classifications of the analogue circuits. Feedback amplifier analysis; - Behavioural modelling of monolithic operational amplifiers by using VHDL-AMS and Analogue Behavioural Modelling feature in the Cadence PSpice® environment; - Analysis and design of the basic inverting and non-inverting amplifier circuits, using voltage-feedback and current-feedback op amps; - Analysis and design of transimpedance amplifiers (TIAs) and voltage-to-current converters for a grounded load; - Analysis and design of three-op amps instrumentation amplifiers; - Development of programmable active-RC filters, using four-terminal CFOAs; - Synthesis of selective LC amplifiers and LC oscillators, using four-terminal CFOAs; - Behavioural modelling and prototyping of monolithic frequency-to-voltage and voltage-to-frequency converters.