Radio Frequency Fingerprint(RFF) originates from the differences in transmitter circuit design and the manufacturing tolerance of the hardware circuit in the production process. It is an emerging equipment identification and authentication technology. Modeling the generation mechanism of RFF is the basis for its in-depth research. Based on a general Zero Intermediate Frequency(ZIF) digital communication transmitter architecture, the influence of each component in the transmitter on RFF is analyzed, and the corresponding RFF time-domain baseband model is established as well. In addition, several important time-domain parameter tolerances of communication standards are summarized. The maximum Root Mean Square Error Vector Magnitudes(RMS EVMs) of the two typical modulation methods, Quadrature Phase Shift Keying(QPSK) and 16 Quadrature Amplitude Modulation(16-QAM), are mainly studied under the LTE standard. Finally, through theoretical derivation and Matlab simulation, the upper and lower bounds of Direct Current(DC) offset, In-Phase/Quadrature(I/Q) gain imbalance, I/Q quadrature offset error, I/Q filter offset, oscillator phase noise, and power amplifier nonlinearity parameters are given. The changes of the constellation diagram under the critical conditions of various RFF parameters are also analyzed, which provides reasonable parameter guidance for the future research of RFF extraction and identification.