**Abstract**

The capability of memristor devices to perform weight changes upon electrical pulses mimics the analogous firing mechanism in biological synapses. This capability delivers the potential for neuromorphic computing and pushes renewed interests in fabricating memristor with analog characteristics. Nevertheless, memristors could often exhibit digital switching, either during the set, reset, or both processes that degenerate their synaptic capability, and nanodevice engineers struggle to redesign the device to achieved analog switching. This chapter overviews some important techniques to transform the switching characteristics from digital to analog in valence change and electrochemical metallization types memristors. We cover physical dynamics involving interfacial diffusion, interfacial layer, barrier layer, deposition, and electrode engineering that can induce digital-to-analog switching transformation in memristor devices.

**Keywords:** digital, analog, switching transformation, switching mode, resistive memory, synaptic plasticity
