Design Of Voltage Controlled Oscillator For Low Voltage Bluetooth

Bluetooth Low Energy(BLE)is a low-cost and low-power short-distance wireless communication technology,which has been widely used.As the key module of phase-locked-loop(PLL)in radio transceiver of wireless system,the power consumption of voltage controlled oscillator(VCO)is directly related to the power level of the whole system.As an important way to achieve low power consumption,reducing power supply voltage has been actively pursued by industry and academia in recent years.In this thesis,a VCO circuit is designed for the application of PLL system in low voltage Bluetooth.It can generate quadrature signal and meet the requirement of low power consumption.After introducing and summarizing the challenges faced by VCO and quadrature frequency dividing circuit under low supply voltage,this thesis adopts Class-C LC-VCO and DCVSL-R quadrature frequency dividing circuit to design.In order to further optimize power consumption and phase noise performance,a dynamic body bias circuit is proposed,which makes the substrate voltage of cross-coupled pairs follow the oscillation waveform dynamically,avoids the cross-coupled pairs entering the linear region when they output large amplitude signals,and deteriorates the quality factor of resonance network;In order to improve the output signal amplitude of quadrature signal generation circuit,a full swing quadrature generation circuit is proposed.By adding nmos cross-coupled pair,the discharge speed of parasitic capacitive charge of output node is accelerated,and the output voltage swing reaches the power supply voltage.Based on TSMC40 nm CMOS technology,a VCO circuit for low-voltage Bluetooth is designed and verified by post-simulation.The simulation results show that under 0.8V supply voltage,the VCO oscillates within 30ns~45ns;the single-ended swing of the core is 940mV~993mV,consuming 1.2mA~1.3mA current;the VCO can cover the frequency range of 2.4GHz~2.485 GHz at all process corners,and the phase noise is-121.5dBc/Hz@1MHz ~-123.3dBc/Hz@1MHz.