This book describes several techniques to address variation-related design challenges for analog blocks in mixed-signal systems-on-chip. It Includes built-in testing techniques, linked to current industrial trends.Introduction.- Process Variation Challenges and Solutions Approaches.- High-Linearity Transconductance Amplifiers with Digital Correction Capability.- Multi-Bit Quantizer Design for Continuous-Time Sigma-Delta Modulators with Reduced Device Matching Requirements.- An On-Chip Temperature Sensor for the Measurement of RF Power Dissipation and Thermal Gradients.- Mismatch Reduction for Transitiors in High-Frequency Differential Analog Signal Paths.- Summary and Conclusions.