Negative Group Delay Devices: From concepts to applications introduces the theoretical concept, analysis, design methodology and implementation of negative group delay (NGD). The NGD concept is a recent topic in electrical and electronic engineering research based on an unconventional function; the generation of an output signal seemingly in time-advance of the input signal. The NGD function has been exploited to develop experimental high-performance electronic devices, and novel design features of radio frequency (RF) and microwave electronic devices, such as filters, power dividers and amplifiers. Examples include the realization of non-Foster reactive elements, shortening or reducing delay lines, enhancing the efficiency of feedforward linear amplifiers, improvement of phase shifters accuracy and bandwidth, equalization of electrical interconnect effects for the microwave, digital and mixed signal integrity improvement, and minimizing beam-squint in series-fed antenna arrays. The aim of the book is to advance understanding of the NGD principle and its applications. Recent results and outcomes for the different methodologies used to elaborate the NGD function are shared in each chapter, and approaches relevant to various devices are described. This book will be of particular interest to researchers, academics and postdoctoral students interested in signal processing in electronic, radio frequency, microwave and optoelectronic devices, and particularly those investigating unconventional circuit and system design.