自耦合電壓控制LC振盪器之設計

Abstract

本論文提出利用自耦合的方法來實現一調整頻率之LC振盪器(LC Oscillator)。此控制頻率變化的方法,乃是利用四相位LC振盪器(Quadrature LC Oscillator)的電流耦合以及環型振盪器(Ring Oscillator)的自耦合之觀念延伸而來。在四相位LC壓控振盪器是利用耦合信號電流與LC振盪器的信號電流有固定的90度相位差,並藉由調整兩者的信號電流大小比來控制LC振盪器頻率,而環型振盪器是利用延遲時間的方式來獲得360度相位。本論文所提出的振盪器是利用四相位振盪器的電流耦合觀念以及利用延遲時間來作相位偏移,提出自耦合電壓控制振盪器的想法。此電路包含了LC諧振埠,緩衝器,具有時間延遲的相依電壓源模組與耦合電晶體。我們使用台積電 0.35um 3P3M SiGe BiCMOS 製程來模擬此振盪器電路。經模擬結果,在延遲時間從0.2ns變化1.2ns時,其耦合電流為3mA,此振盪器振盪頻率從689MHz到958MHz以及當耦合電流為15mA,振盪頻率從585MHz到1.19GHz。

This thesis presents a self-coupled voltage-controlled LC oscillator which originates from the concept of both the current coupling of quadrature LC oscillator and the self coupling of ring oscillator. The quadrature votage-controlled LC oscillator uses the ratio of couple transistor current and LC oscillator current having a phase difference of 90 to control the oscillator frequency, while the ring oscillator uses the delay to obtain a phase shift of 360. The proposed oscillator uses the concept of current coupling of quadrature oscillator and the concept of phase shift via the delay to obtain a self-coupled LC voltage-controlled oscillator. The proposed schematic, therefore, consists of LC resonant tanks, voltage-controlled delays, two buffers, and coupled transistors. The circuit has been simulated via tsmc 0.35um 3P3M SiGe BiCMOS technology. The simulation results for the delay time varying from 0.2ns to 1.2ns,yield the oscillation frequency from 689MHz to 958MHz when the coupled current is 3mA and 585MHz to 1.19GHz when the current is 15mA。