This paper presents the impact of process faults — such as parameter variations and process variations — on specific parameters of a low noise amplifier (LNA) — like noise figure (NF), linearity (1 dB CP, IP3), S-parameters (S11, S21) voltage output signal. A review of mathematical types that shows the relations between specifications and parameters of the LNA is a tool to explain the behavior of the circuit under the presence of process shifts and parasitic elements. A differential source degeneration LNA has been designed in a 90nm CMOS UMC technology to validate the theoretical conclusions and investigate if it is possible to restore the circuit prescriptions to the desired values, varying one or more parameters.