Reference voltage generation circuits and related methods are disclosed. An example reference voltage generation circuit includes a voltage generating circuit including an enhancement mode (E-mode) gallium nitride (GaN) transistor, the voltage generating circuit to, in response to a first clock signal having a first phase, generate a first voltage associated with the E-mode GaN transistor, and, in response to a second clock signal having a second phase different from the first phase, generate a second voltage associated with the E-mode GaN transistor, and a switching capacitor circuit coupled to the voltage generating circuit, the switching capacitor circuit to generate a reference voltage based on a difference between the first voltage and the second voltage.