A SAR-Based Fast Automatic Digital Calibration Circuit of On-Chip Clock

The clock signal is a critical factor for digital circuits. However, during the chip manufacturing process, variations in conditions such as power supply voltage, process, temperature, and more can lead to deviations in oscillators frequency compared to the design specifications, the value may even reach a variation range of ± 35%, which potentially impact the functionality and performance of the chip. In order to compensate the influence of these non-ideal factors on the oscillator frequency. An on-chip fast digital automatic calibration with Successive Approximation Register (SAR) logic is proposed, compared with the traditional logic of calibration by addition and subtraction, the proposed circuit can exhibit high calibration speed. 8-bit control word on-chip fast digital automatic calibration module of proposed is designed in TSMC 180nm process, and the proposed calibration scheme has been applied to the actual chip to verify the reliability of the designed scheme, which has an important impact on the use of the internal clock of the chip.