Design Of Key Modules Of Frequency Synthesizer For BLE Application

Bluetooth is a low power,low cost,short distance wireless communication technology,which is widely used in the market of wireless personal network.Frequency synthesizer serves as the local oscillator of the Bluetooth transceiver,which is a key block can impact on the basic performance and index of the Bluetooth.The main work of this thesis is to design the module of PFD/CP and a function-N divider based on the technique of ?? modulator.The development and research status of frequency synthesizer is reviewed.The basic principle of frequency synthesizer is analyzed.In order to assess the performance of the system,a phase domain linear model and noise model of a decimal frequency divider is established.Based on TSMC55nm CMOS process,the module of PFD/CP and the function-N divider are designed and realized.On the basis of analyzing the PFD and CP circuit structure,the paper has proposed the PFD with a circuit to prevent dead zone.Besides,a Charge Pump circuit applying replica technology is designed to avoiding non-ideal characteristic.On the basis of analyzing the common frequency divider structure,the paper has designed a divide-by-2 circuit at a high speed and a I/Q differential circuit,and also designed a high speed 20 bit MASH 1-1-1 modulator and an 8 bit programmable frequency divider with a division ratio from 1 to 255.The simulation results show that the PFD/CP module has correct logic function with the 16MHz reference frequency.CP current mismatching ratio is less than 3%at the output range of 0.3V-0.7V.The maximum working frequency of the function-N divider is not less than 2.8GHz,the frequency resolution is about 62Hz,and the current consumption is less than 1mA under the IV supply voltage.The implemented frequency synthesizer occupies an area of 0.7mm×0.65mm,the locking time is below 40?s,and it consumes 2mA under 1V supply voltage,which meet the requirement for application.