A method and system of synthesizing impedance in a radio frequency (RF) amplifier includes receiving a voltage signal at a passive mixer. The passive mixer down-converts the voltage signal into a baseband frequency. The method includes converting the voltage signal into a digital signal. Further, the method includes performing convolution of the digital signal with an impulse response. The impulse response is of a low Q impedance and is programmable. Furthermore the method includes generating a current signal based on output of the convolution. Furthermore the method includes performing up-conversion of the current signal in the passive mixer. The passive mixer performs impedance transformation of the low Q impedance. Moreover, the method includes providing the current signal via the passive mixer to synthesize desired impedance in the RF amplifier, thereby controlling frequency response of the RF amplifier.