Let’s address the elephant in the room. The search for "analog design essentials by willy sansen pdf 2021" is high because:
Chapters on mismatch (important for data converters and sense amplifiers) and noise (including subthreshold noise) are still cited in modern papers. Sansen’s for MOS transistors is a standout. analog design essentials by willy sansen pdf 2021
If you are looking for a "2021 PDF" of this book, you are likely a student or an engineer seeking a reliable reference for CMOS design. Let’s address the elephant in the room