A fractional-N frequency divider for multi-standard wireless transceiver fabricated in 0.18 μm CMOS process

With the rapid evolution of wireless communication technology,integrating various communication modes in a mobile terminal has become the popular trend.Because of this,multi-standard wireless technology is one of the hot spots in current research.This paper presents a wideband fractional-N frequency divider of the multi-standard wireless transceiver for many applications.High-speed divider-by-2 with traditional sourcecoupled-logic is designed for very wide band usage.Phase switching technique and a chain of divider-by-2/3 are applied to the programmable frequency divider with 0.5 step.The phase noise of the whole frequency synthesizer will be decreased by the narrower step of programmable frequency divider.△-Σ modulator is achieved by an improved MASH 1-1-1 structure.This structure has excellent performance in many ways,such as noise,spur and input dynamic range.Fabricated in TSMC 0.18 μm CMOS process,the fractional-N frequency divider occupies a chip area of 1130 × 510μm2 and it can correctly divide within the frequency range of 0.8-9 GHz.With 1.8 V supply voltage,its division ratio ranges from 62.5 to 254 and the total current consumption is 29 mA.