A phase shifter and related load device are provided. The phase shifter includes a phase shifter core and load devices. The phase shifter core has an input port for receiving an input signal, an output port for outputting an output signal, and connection ports. The load devices are coupled to the connection ports, respectively. At least one of the load devices includes first varactor units each having a first node and a second node, where first nodes of the first varactor units are coupled to a first voltage, second nodes of the first varactor units are respectively coupled to a plurality of second voltages, and the second voltages include at least two voltages different from each other. The phase shifter and related load device are capable of mitigating effects resulted from varactor's non-linear C-V curve.