The design of a crystal-off oscillator with robust on-chip PVT compensation

In recent years, with the rapid development of process technology and portable electronic products, many devices have become thin, light, and power-efficient, and it is relatively important to provide a stable clock frequency generator for the system. In this paper, we propose an automatic PVT calibrated ring oscillator. By automatically compensating for temperature variations in the current source circuit, digital control is used to switch the working blocks to compensate for process variations. In addition, voltage-controlled capacitors are used to ensure that the supply voltage variability is stable to frequency. Our simulation results use an on-chip calibrated oscillator implemented in TSMC 90nm 1P9M CMOS process.