A semiconductor memristor device based on a 300-nm ZnO thin film was fabricated by direct-current reactive sputter. The memristive behavior of this device was confirmed by time dependent current-voltage (I-V-t) measurements, and the distinctive pinched hysteresis I-V loops of the memristor were observed. Structural analysis of the ZnO memristor was carried out using both X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). After physical implementation of the memristor, an operational transconductance amplifier (OTA) based memristor circuit was designed to emulate the ZnO-based semiconductor memristor for use in memristor-based circuit applications. All simulations were in good agreement with experimental results. In addition, a comparison of the proposed circuit with other memristor emulators was presented.