Compound semiconductor technology appears to be at the age of maturity when applications will have been defined, yields are high enough and well established, and gallium arsenide and related compounds have carved many important niches in electronics. This text reviews the state-of-the-art of compound semiconductor electronics. Its emphasis is on the microwave, millimeter wave, and submillimeter wave devices and on emerging wide band semiconductor materials. The book is written by leading experts in compound semiconductor devices from both industry and academia and strikes the balance between practical applications, record-breaking results, and design and modelling tools specific for compound semiconductor technology. Engineers, scientists, and graduate students working in solid state electronics and in the area of compound semiconductor electronics should find this book useful. This book could also be used as a text or a supplementary text for graduate courses in this field.