This book demonstrates why highly-digital CMOS time-encoding analog-to-digital converters incorporating voltage-controlled oscillators (VCOs) and time-to-digital converters (TDCs) are a good alternative to traditional switched-capacitor S-D modulators for power-efficient sensor, biomedical and communications applications. The authors describe the theoretical foundations and design methodology of such time-based ADCs from the basics to the latest developments. While most analog designers might notice some resemblance to PLL design, the book clearly highlights the differences to standard PLL circuit design and illustrates the design methodology with practical circuit design examples.