The book covers all the aspects of theory, analysis and design of Electronic Circuits for the undergraduate course. It provides all the essential information required to understand the operation and perform the analysis and design of a wide range of electronic circuits, including MOSFET as a switching and amplifier circuits, feedback amplifiers, oscillators, voltage regulators, operational amplifiers and its applications, DAC , ADC and Phase Locked Loop. The book is divided into four parts. The first part focuses on the fundamental concepts of MOSFET, MOSFET construction, characteristics, and circuits - as a switch, as a resistor/diode, as an amplifier and current sink and source circuits.The second part focuses on the analysis of voltage-series and current-series feedback amplifiers. It also explains the Barkhausen criterion for oscillation and incorporates the detailed analysis of Wien bridge and phase-shift oscillators.The third part is dedicated to the basic of op-amp and discussion of a variety of its applications. The fourth part focuses on the V to I and I to V Converters, DAC and ADC, and Phase Locked Loop.The book uses plain and lucid language to explain each topic. The book provides the logical method of explaining the various complicated topics and stepwise methods to make understanding easy. The variety of solved examples is the feature of this book. The book explains the philosophy of the subject, which makes the understanding of the concepts very clear and makes the subject more interesting.