Ultra Wideband Frequency Source Large Dynamic Range Alc System Research

In recent years, with the market calls for more requirements on the operating frequency, bandwidth, power flatness and dynamic range of the output power of the frequency synthesizer, the automatic level control (ALC) system attracts significant attention from people.According to the requirements of laboratory research, a digital broadband and wide dynamic range ALC scheme is presented and designed based on the idea of "combining small dynamic range of closed-loop in small step with large step attenuator".At the same time, in order to satisfy the needs of the ALC system, a wideband low noise amplifier is designed, simulated and tested.First, this paper introduces the development and application of ALC technlogy. After comparing various kinds of ALC structure, a broadband and wide dynamic range ALC scheme is proposed. Then the feasibility of the program has been verified by calculating the gain indicator of the design. Later, detailed designs and realizations of all parts including controller, attenuators, LNA, MMIC amplifier, directional coupler and power detector have been carried out. Finally, the hardware circuit has been fabricated and tested. Based on the analysis of test data, suggestions for improvement are presented.Otherwise, based on the theory of broadband amplifier design, with the help of ADS, an ultra-wide band LNA from0.5GHz to4GHz is desined. In the covered band, the LNA provides about10dB gain, gain-flatness of less than±1dB,noise figure of less than2.7dB, linear output power (P1dB) of more than14dBm.In the operation frequency band from0.5GHz to4GHz, the ALC system ultimately realizes the specifications of maximum output power+10dBm with70dB dynamic range,±1.5dB power flatness and0.5dB power resolution by carefully debugging.