Current-mode signal processing offers superior linearity and flexibility in front-end implementation. The linearity of a low-input-impedance Trans-Impedance Amplifier (TIA), which is used as a buffer stage that follows a passive mixer, is important in determining the overall receiver performance. In this paper, the analysis for optimizing the linearity of the feedback TIA is presented. The results helps to estimate the minimum required amplifier gain for a targeted linearity. The accuracy of the analysis is validated by simulating different TIA parameters.