Abstract: In view of the characteristics of broadband micro-power wireless communication technology (470MHzto 510MHz) with high rate and sudden signal transmission, a digital-analog hybrid feedback and high-speed dual-mode AGC(DFA-AGC)is proposed in the process of designing broadband micro-power RF front-end chip, which removed loop filter and ADC. In order to realize the rapid response of AGC, a new type of rail-to-rail input with constanttransconductance voltage loopand an improved push-pull output structure with current mirror load areproposed to improve the conversion rate, and a full-wave envelope detector with a fully symmetric differential structure is designed to reduce the detection time of the differential signal envelope..Considering the electromagnetic interference in practical application scenarios, a fast and slow locking dual-mode adaptive switching algorithm is designed to achieve fast tracking and locking in fast locking mode, and effectively avoid peak interference in slow locking mode. The AGC is designed by SMIC 40nm CMOS process. Simulation results show that the locking and gain stabilization time is less than 10 microseconds, and the dynamic range of receiving gain is greater than 90 dB. The actual test results show thatthe stability time in fast lock mode is about 9 microseconds, and the stability time in slow lock mode is about 30 microseconds, and the power consumption is less than 1 mW.