UTMI-Based Clock Calibration Method

This paper proposes a UTMI (Universal Transceiver Macro Interface)-based clock calibration method to address the clock frequency error in the UTMI physical layer under high-speed scenarios. By detecting the SYNC field of the SOF (Start of Frame) packet to recover the reference clock signal, combined with duty cycle calculation and a binary capacitor array adjustment mechanism, precise compensation for clock phase delay is achieved. This ensures a duty cycle close to 50%, thereby reducing errors and meeting USB protocol requirements. Experimental results demonstrate that the proposed method controls duty cycle errors within $\pm 5 \%$, effectively mitigates the impact of PVT (Process, Voltage, Temperature) factors on clock stability, and satisfies the USB protocol’s frequency error tolerance of ± 500ppm.