Research Of Quadrature Voltage Controlled Oscillator Based On 0.18μm CMOS Technology

In recent years, with the development of wireless communication technology, the RF front-end circuit design of wireless transceiver also suffered a new challenge. The RF front-end circuit of wireless transceiver needs receiving weak useful signals from the antenna and emitting RF signals successfully. The process requires the local oscillators providing accurate quadrature output signals to realize the down-conversion of received signals or up-conversion of radio frequency after mixing in the mixer. At present, the RF front-end circuit design of wireless transceiver is mainly using CMOS technology. In this paper, design of quadrature voltage controlled oscillators based on TSMC 0.18μm CMOS technology have a certain significance.After studying the design theory of low voltage, low power and low phase noise, two quadrature voltage controlled oscillators based on CMOS technology are presented. The main work of this paper can be summarized as follows:(1) A 2.4GHz substrate coupled quadrature voltage controlled oscillator is designed based on the TSMC 0.18μm CMOS process. By using the back-gates of the PMOS switching transistors to be coupling terminals to achieve the quadrature outputs, the proposed circuit has the advantages of no additional noise source and power dissipation in the coupling process. By switched self-biasing the tail transistors in a complementary manner, the output signals of the QVCO are injected back into the gates of the tail transistors as biasing voltages to improve the phase noise. Besides, the forward back-gate biasing technique is used to the NMOS switching transistors, so the proposed QVCO can be operated at reduced supply voltage and power dissipation. The simulation results show that the phase noise is-123.2dBc/Hz at 1MHz offset frequency from the carrier frequency of 2.35 GHz, while it consumes3.3mW under a 1.2V supply voltage. The free-running frequency of the QVCO is tunable from 2.13~2.87 GHz as the tuning voltage is varied from 0~1.2V.(2) A 3.4GHz current-reused quadrature voltage controlled oscillator is designed based on the TSMC 0.18μm CMOS process. By stacking two differential voltage controlled oscillators in series, the structure can implement two VCOs share the same current. By using the back-gates coupling theory and putting a capacitor on output terminals can realize exchange coupling as well as reduce phase noise. The simulation results show that the phase noise is-114.4dBc/Hz at 1MHz offset frequency from the carrier frequency of 3.44 GHz, while it consumes 3.6mW under a1.2V supply voltage. The free-running frequency of the QVCO is tunable from 3.41~3.50 GHz as the tuning voltage is varied from 0~0.5V.