Design Of Key Modules For Sub-8Ghz Cmos Ultra-wideband Frequency Synthesizer

With the continuous development of wireless communication technology,more and more communication standards have been proposed,and the communication frequency band is also getting higher and higher.At the same time,under the trend of chip integration,in order to achieve the goals of small area,low power consumption and low cost,it has become a research hotspot at home and abroad to integrate radio frequency transceivers that meet multiple communication protocols into one chip.High-performance frequency synthesizers are essential for source that provides local oscillator signals for RF transceivers.Therefore,as the key modules in the frequency synthesizer,the VCO and divider designed in this thesis have high research significance and engineering application value.Sub-6GHz covers most of the frequency bands of 2G/3G/4G/5G mobile communications.Considering the future development of 5G mobile communication,this design expands the frequency band to Sub-8GHz.Based on the 65 nm CMOS process,the VCO,feedback divider and quadrature divider are designed respectively.The VCO designed in this thesis adopts two Inductance-Capacitance Voltage-Control Oscillator(LC-VCO)combinations with tuning ranges of 8-12 GHz and 12-16 GHz to achieve a wide tuning range of 8-16 GHz.The resonant,is composed of a high-Q inductor with two parallel top metal layers structure,a 6-bit switched capacitor array and a varactor,which realize the functions of low phase noise and wide tuning range.In this design,a pre-2 frequency divider composed of a current-mode logic structure and a programmable divider composed of an improved 2/3 dual-mode frequency divider cascade structure are used to form a feedback frequency divider with a frequency division ratio ranging from 16 to 132.The quadrature dividers using current mode logic structure form a divide-by-two chain to achieve quadrature signal output in the 500 MHz to 8 GHz frequency range.This design is based on the 65 nm CMOS process,and the overall layout area is 1.5mm × 0.95 mm.The post-simulation results show that the VCO has a frequency tuning range of 7.97-16.18 GHz,the phase noise is less than-114.66 d Bc/Hz@1 MHz,and the core current is less than 15 m A under the1.2V supply voltage.Under the 1.2V supply voltage,the pre-2 divider achieves correct frequency division in the frequency range of 8-16 GHz,the maximum operating frequency of the programmable multi-mode frequency divider is 8 GHz,and the frequency division ratio range is 8 to 127.The total power consumption of the feedback divider is less than 7m A.The quadrature divider realizes the output of 500 MHz-8 GHz quadrature signals under the 1.2V supply voltage,and the total power consumption is less than 20 m A.All design meet the requirements of the design specifications.