This is a subject where you can score easily once you grasp the basics properly (12-14 marks).You don't even need to invest too much time for revising this subject once you are clear with the fundamentals.
Sedra and Smith’s "Microelectronic Circuits" is an all-inclusive book, which serves to detail out the ABC of Analog Circuits in a detailed manner. The concepts are clearly explained and easily understandable. This book along with "Design with Operational amplifiers and Analog integrated circuits" by Sergio Franco Covers almost every topic in analog circuits for GATE ECE.
Other Textbooks;
Online materials: