Research Of Reconfiigurable VCO For GPS/BeiDou/TD-LTE-A

Voltage controlled oscillator is an important part of the PLL and synthesizer in wireless communication system. It can affect the performance of the whole wireless communication system. Thanks to fast development of wireless communication technology and CMOS integrated circuit technology, the voltage controlled oscillator has been greatly developed. At the same time, it is also facing serious challenges.Recently, more and more wireless communication standards are emerged together, which lead to a growing demand of the terminals that can work under different wireless communication standards. In response to this requirement, this paper analyzes the principles of the VCO, the methods of performance optimization and the configurable issues. A VCO which can support GPS, BeiDou, and three standards of TD-LTE-Advanced is proposed. Its frequency can cover the GPS L1band (1575.42MHz, the bandwidth2.046MHz), BeiDou B1band (1561.098MHz, the bandwidth4.092MHz), B2band (1207.14MHz, the bandwidth24MHz) and TD-LTE-Advanced (2570-2620MHz).The circuit is designed in SMIC0.18um process and simulated by cadence Spectre RF simulator. The result indicates that it can work under the four bands above, and the smallest phase noise is-107dBc/Hz at1-MHz offset, the lowest conversion gain is65.7MHz/V with good linearity.