Phase locked loop frequency synthesizer using multiple dual modulus prescalers

摘要

An improved frequency synthesizer suitable for use in mobile and portable radio applications using multiple dual modulus prescalers to achieve high frequency operation and low current drain. A first high speed prescaler of limited size is used in conjunction with a second prescaler to avoid the use of one large high speed prescaler to attain high frequency operation. Consequently, the frequency synthesizer can be constructed using only a minimum amount of high speed, high current drain logic thereby reducing costs and power consumption.