This research thesis aims to develop a system composed by a a CMOS power amplifier and built-in sensors for variability monitoring and compensation. The integration of monitoring systems with high frequency analog circuits is commonly used for performance optimization and control. In addition, built-in sensors are used in quality testing, improving the yield by detecting circuit faults during the fabrication of these. Typically, most of the built-in sensors are electrically connected to a node of the circuit under test, affecting its performance. In tuned power amplifers, for instance, a small load variation can cause a degradation of its output power and effciency. Hence, the integration between the circuit under test and the monitoring block should be carefully designed. These loading effects can be avoided using non-invasive solutions such as temperature sensors. An integrated circuit composed by a CMOS power amplifer, two amplitude detectors and a temperature sensor is implemented in this work. The degradation of the power amplifier performance due to variability effects is accelerated by increasing its supply voltage. A feedback loop is added to control and adjust the system operation, stress the amplifier and accelerate its degradation, monitor the amplifier performance using the sensors and compensate the observed degradation. The design of each one of the main parts of the system is presented through this work, explaining their theoretical basis and validating their operation with simulations results. Finally, all the parts are integrated together, and a feedback loop with a control algorithm is proposed to monitor and compensate the DUT variability effects.