Analysis of the Double-conversion Scheme Based on Single Local Oscillator

For strict requirement, the local oscillator is always a difficult problem when designing the communication system based on the double-conversion scheme. In this paper, a kind of improved double-conversion scheme is introduced in which single local oscillator is needed, and key issues about this double-conversion scheme with single local oscillator are also discussed. The scheme is possessed of the advantages of traditional double-conversion system, but simultaneously decreases the difficulty when realizing the local oscillator. So, it is favorable in system miniaturization and integration. Based on careful analysis of the new scheme and an engineering example, some formula and designing rule of system parameters, such as bandwidth and center frequency of intermediate frequency filter, are proposed. The method discussed in this paper is also applicable in other frequency band