Frequency synthesizer for use in mobile terminals of wireless communication systems to provide receiving and transmitting frequencies uses oscillating devices to generate frequencies

摘要

Oscillating means (1,2) are phase locked loops using quartz oscillators that have different frequency tuning ranges and a frequency synthesizer (3) provides frequency ranges of 925-960, 1805-1880 and 2110-2170 MHz. A first shifting device (4) is of the image reject type of mixer to minimize unwanted effects and its output is filtered by a filter (10), while a shifting device (5) generates the transmitting and receiving frequencies.