Memristor applied in delay locked loop for high lock speed and wide frequency range

Locking speed and operating frequency range of DLL is limited to the delays of its VCDL. Since memristor resistance changes according to external bias, memristor can be used as programmable resistor. In this paper, memristor is applied to VCDL as variable resistor where the memristor resistance regulates total delay of the VCDL. VCDL consists of current starved inverter as the delay unit. A voltage to current converter (VCC) is used to convert control voltage from capacitor, Vc to control current, Ic. The control current, Ic with memristor resistance generates new voltage, Vr that regulates the delay. Compared to conventional DLL, the proposed DLL design offers one more control parameter which is Vr. By applying memristor to the DLL, the control voltage Vc can be further manipulated. Simulation results show that proposed DLL with memristor has higher locking speed and can lock higher input frequency compared to conventional DLL without memristor. Therefore, higher locking speed and wide operating frequency range are both achievable by proposed DLL with memristor.