Abstract: The traditional moonlet narrowband receiver’s signal bandwidth is narrow, so a low sampling rate is needed and many commercial ADC products may meet this requirement. In this paper, a broadband high intermediate frequency （IF） receiving scheme is proposed for moonlet radio terminal receivers. In this scheme, intermediate frequency is designed at 70MHz, and signal bandwidth is 20MHz. Analog-to-Digital Converters （ADC） play an important role in digital communication or moonlet receivers. The sampling rate and conversion bits are the main index for ADC’s characteristics. According to the requirements mentioned above, the factors which may affect ADC’s Signal-to-Noise Ratio （SNR） characteristics are analyzed in detail, and the corresponding calculated results, such as sampling rate and conversion bits are given. In the end, the relations among the ADC’s SNR, sampling rate and conversion bits are discussed.