One of the gold standards for analog CMOS IC design. Razavi has a tendency to borderline hand-wave some concepts away, shrouding them in some borderline form of mysticism, or even leaving acquiring understanding "as an exercise for the reader" but fortunately these are far and few. Pedants and academics may find text like Gray and Meyer more to their liking, but for the working professional the book strikes a good balance between serving as a reference and insisting on stringent rigor.