“…The DCC circuits [17,20,21] can cover a wide frequency range, but the unit delay generates significant correction errors at high frequencies. The DCC circuits [16,23,24,25,26,27,28,29] utilize the long delay chain with plenty of small delay units to cover a wide operating frequency range, which leads to very complex control circuits and increases circuit area. Additionally, the total delay length and the unit delay vary with the process, voltage, temperature (PVT) variations [18,21,30,31], which seriously limits the operating frequency range of circuit and affects correction accuracy at different frequencies.…”