基于电流折叠技术的CMOS全差分VCO设计

Design of CMOS Full Differential VCO Based on Current Fold Technique

针对目前通信系统应用上对压控振荡器的片上集成、宽调谐、调幅、启动特性和功耗等提出的综合性要求，分析和设计了一种压控调频调幅振荡器，其延迟单元采用全差分结构，以消除共模噪声和增加延迟控制的灵活性；并利用交叉耦合的差分负阻和电流折叠的正反馈技术进行频率调谐，使之在宽频范围内具有常数振荡幅度。采用0．5μmCMOS工艺进行Spice仿真，结果表明振荡器具有34～197MHz的宽调谐范围，并能保持常数振荡幅度，功耗仅10mw，启动时间仅52ns。系统还能在0．5～2．0V范围内进行良好的线性调幅。

On- chip VCO with comprehensive target, such as wide tuning, amplitude adjusting, good start up time and lower power,is required in current communication system. A frequency and amplitude adjusting VCO is designed and analyzed. Full differential configuration is used to avoid common mode noise and achieve controlling flexibility of delay cells. Negative resistance differential complementary cross - coupled pair and regenerative feedback technique with current fold are applied to adjust frequency with constant amplitude in large range. Under 0.5 μm CMOS process,Simulation results in SPICE indicate that the VCO proposed behaves in wide linear tuning between 34-197 MHz with constant amplitude, 10 mW power dissipation and 52 ns start up time. It also has good linear amplitude adjusting between 0.5-2.0 V.