Abstract: A vector modulator includes a quadrature component generator, configured to generate an input in-phase signal and an input quadrature signal according to an input radio frequency (RF) signal; a switching circuit, receiving a plurality of bits, comprising a plurality of switches controlled by the plurality of bits, configured to generate an output in-phase signal and an output quadrature signal according to the plurality of bits, where the output in-phase signal and the output quadrature signal are related to input in-phase signal and the input quadrature signal; and a combining module, configured to generate an output RF signal according to the output in-phase signal and the output quadrature signal.