A transmitter in a wireless communication system is provided. The transmitter includes a baseband signal processor for detecting an envelope signal, a supply modulator (SM) for producing power to be supplied to a power amplifier using the detected envelope signal, and the power amplifier for receiving voltage from the SM and for amplifying power of a transmit signal. The SM generates a compensation signal corresponding to switching noise generated via switching amplification, and adds the compensation signal and the switching noise. The amplifier of the wireless communication system can produce low switching noise, and the envelope tracking power amplifier can prevent reception degradation due to the noise of the supply modulator.