A Radio Frequency (RF) transmitter and a signal amplification method therefor are provided, in which a signal source generates a signal of a predetermined Intermediate Frequency (IF) band, a local oscillator generates a signal of a predetermined high frequency band as a carrier signal, a power amplifier amplifies the signal received from the local oscillator to a predetermined transmission level, and a parametric mixer module receives the signals from the signal source and the power amplifier and outputs the received signals as a radio signal for transmission. The signal output from the parametric mixer module is transmitted as the radio signal without additional amplification.