A method and apparatuses for generating a reference voltage are disclosed. One example apparatus includes a current source coupled to a first power supply. The current source supplies a first current. A reference memory cell is coupled to the current source at a reference node. The reference memory cell has a select device comprising a chalcogenic semiconductor material. A clamp circuit is coupled between the reference memory cell and a second power supply. The clamp circuit is configured to control a second current such that when the first current and second current are substantially equal, the reference voltage generated at the reference node tracks a threshold voltage of the select device.