Integrated Selective Amplifiers Using Frequency Translation

Integrated band-pass amplifiers with high selectivity and good desensitivity can be realized, using the principle of frequency translation. In contrast to previously proposed systems in which frequency translation is achieved by periodic switching, this system uses analog multipliers as the basic elements, thereby obtaining improved high-frequency performance and reduced distortion. The properties of the analog multipliers are described and a procedure is developed for desensitizing the system characteristics against temperature and parameter changes. Both monolithic and hybrid realizations of the selective amplifier are proposed. Experimental results are given for an integrated prototype which achieves a stable Q of 328 at a center frequency of 1.5 Mc/s.