Research On High Reliability Voltage Controlled Oscillator Based On Silicon-based Materials

Various wireless communication products have gradually emerged recently,lower power consumption and higher level of integration have been the major considerations.As one of the key building blocks in the communication system,the oscillator's performance largely determines the overall performance of the system.The key performances of the oscillator circuit include the operating frequency,tuning range,phase noise,supply pushing,etc.The design consideration of the oscillator vary to different application scenarios,but reducing power consumption,optimizing area,and reducing phase noise have been some general desires.A low-power voltage-controlled oscillator is designed for the a Bluetooth transceiver,which includes a bandgap reference circuit,a low-dropout linear regulator circuit,a core circuit of the voltage-controlled oscillator,a frequency divider circuit,and an output buffer circuit.The basic theories of noise and power supply rejection ratio of the bandgap reference circuit and the low-dropout linear regulator circuit have been reviewed,followed by the design of a low-noise low-dropout linear regulator circuit,and the bias circuits.The circuit structure and phase noise model of the voltagecontrolled oscillator has been analyzed,based on which a varactor array is optimized to improve the linearity of the tuning gain.Moreover,the LC tank is of improved symmetry,and optimized the inductor's Q value to improve phase noise.The circuit was implemented using in Dongbu 0.11?m CMOS process.The test results of the chip show that the tuning range can cover 2.4GHz to 2.48 GHz,the phase noise is-118.6d Bc at 1MHz frequency offset,and the VCO core circuit consumes 1.05 m A from a supply voltage of 1.2.V.The temperature depended characteristic of the oscillation frequency of VCO is analyzed,and a temperature compensation circuit that can significantly reduce the oscillation frequency drift is proposed.The temperature compensation circuit mainly includes a temperature detection circuit,a logic circuit and a voltage bias circuit.The high-frequency voltage-controlled oscillator circuit is designed in Towerjazz 0.18?m Bi CMOS technology.Simulation results show that the tuning range is 23.5GHz-29.6GHz,the phase noise is-107 d Bc at 1MHz frequency offset,and the variation of oscillation frequency is 31 MHz over temperature from-40? to 125?,which is 91% lower than the frequency variation of the voltage-controlled oscillator circuit without temperature compensation circuit.