The Fujitsu MB1519 is a 600MHz dual serial input PLL (Phase Locked) frequency synthesizer designed for cellular telephone and cordless telephone applications. The MB1519 has two PLL circuits on a single chip: one for transmit and the other for reception. Separate power supply pins are provided for the transmit and reception PLL circuits. Transmit PLL contains a low sensitivity charge pump for ease of modulation and reception PLL contains a high sensitivity charge pump for faster lock up time.