Design Of Fractional Frequency Divider For Low Voltage Bluetooth

Bluetooth Low Energy(BLE)RF system is widely used in short-range wireless communication and IoT communication.The fractional frequency divider is an important module of the frequency synthesizer in the Bluetooth radio transceiver,generally including multi-modulus programmable frequency divider and ?? modulator.Therefore,it is important to reduce the power consumption of the fractional frequency divider using a low voltage design.This thesis addresses the problem of low power consumption limiting operating frequency in low-voltage multi-modulus programmable frequency dividers,and the problem of modulators ensuring spurious suppression while reducing hardware overhead.A low voltage fractional frequency divider for Bluetooth RF transceiver is designed in this thesis.In the multi-modulus programmable frequency divider,the 2/3 prescaler is improved.Signal feedforward is achieved by using embedded logic,which divides a single critical path of the traditional ETSPC 2/3 prescaler into two paths.The short-circuit current of non-critical path is reduced by combining the IMETSPC structure afterward;In the design of the modulator,a multi-stage noise shaping modulator(HK-MASH1-1-1)based on output feedback modulator(HK-MASH)is used.The multiplier circuit is simplified under the consideration of the specific application in this thesis.The registers for synchronizing are re-used in the output feedback circuit,reducing hardware.Based on the TSMC 40 nm RFCMOS process,the specific circuit and layout is designed,and pre-simulation and post-simulation is performed in this thesis.The post-simulation results show that at 0.8V supply voltage,the maximum of average current of the fractional frequency divider is 0.427 mA,the frequency resolution is 23 Hz,the division ratio range is 56-255,and the phase noise of the frequency divider is-151.96 dBc/Hz@1MHz,the operating frequency range covers 1GHz-4.5GHz under each process corner,the normalized power is 0.0462mW/GHz@4.5GHz,and there is no obvious spectral spurs,meeting the design specifications.