A 4.5-GHz 256∼511 multi-modulus frequency divider based on phase switching technique for frequency synthesizers

A 4.5-GHz 256~511 multi-modulus frequency divider for frequency synthesizers is demonstrated. The proposed frequency divider is based on phase switching technique and cascade of divide-by-2/3 cells, it prevents the presence of control logic gates in the highest frequency division block in order to achieve the highest operation frequency under low power consumption; the division ratio is ranged from 256 to 511 continually with step of 1. A prototype has been implemented in 0.35μm SiGe BiCMOS technology; occupying 0.06mm² chip areas. The operating frequency range is 2.3~4.5 GHz. The multi-modulus divider consumes 7.1mA current from 3V supply voltage.