1. A voltage generator, comprising: a cascade resistor having a first feedback terminal and a second feedback terminal; a first regulator, which is configured to output a first output voltage and comprises a multi-power domain operational amplifier, which has a negative feedback configuration, operates in a first power domain and a second power domain different from the first power domain, and has an inverting input terminal receiving a first reference voltage, and a noninverting input terminal coupled to the first feedback terminal; and a second regulator, which is configured to output a second output voltage, and comprises a single power domain operational amplifier operating in a third power domain and having the negative feedback configuration, wherein the single power domain operational amplifier has an inverting input terminal receiving a second reference voltage and a noninverting input terminal coupled to the second feedback terminal.