Abstract: A digital intermediate frequency receiver is optimized based on the state of art engineering implementation techniques, and three typical RFAF （radio frequency analog front-end） circuits are compared and simulated, and then the circuit architecture and features of RFAFs suitable for a large dynamic range and broadband digital receiver are discussed. A new type of digital RF AGC circuit is provided. A DIFR with （10 MHz） bandwidth, （-100^）（-10 dB） dynamic range and （80 MHz） sampling rate is optimized, the parameters allocation and optimization of the RFAF are studied, the relationship between the RFAF's gain, noise factor as against the dynamic range, and RF AGC code of the DIFR is deduced and simulated.