Design and Implementation of Ku-band Voltage Control Oscillator and X-band frequency synthesizer for wireless communication

In recent years, the wireless communications industries become more and more popular due to market demand. With the circuit operating frequency constantly upgrading, the high-frequency integrated circuit design is increasingly important. For system circuits, whether analog or digital RF applications, we need a clean clock generator to provide a stable and accurate signal source to improve the system performance. In this thesis, we achieve a clock generation circuit in three different frequency bands. A Ku-band low noise voltage controlled oscillator, an X-band frequency synthesizer and an X-band radar frequency modulated continuous wave generator, respectively. In chapter 2 we detailed introduce the principles and analysis of phase-locked loop circuits. In chapter 3, a Ku-band voltage controlled oscillator has been designed and implemented. Using LC resonant architecture with the NMOS cross-coupled pair can reduce the output phase noise. To improve the overall resonator quality factor, an additional capacitance is added and the use of inductance can be deducted. In order to avoid the load effect affecting the operating frequency and the characteristics of circuit, a common source buffer amplifier is added and the drain resistors can be replaced by inductance to reduce the resistive loss and the noise of the circuit. In Chapter 4, an X-band frequency synthesizer has been designed and implemented. Using a LC voltage controlled oscillator with NMOS cross couple pairs to achieve low power consumption, good phase noise and greater output power. The whole divider chain circuit can be implemented by the current-mode logic frequency divider (CML), true single-phase clock (TSPC) frequency divider and a multi-mode frequency divider (MMD). The circuit is composed by phase frequency detector with modified static type, charge pump with only NMOS switches, third-order loop filter and the above VCO and divider chain. In addition, the circuit at low power conditions also has good characteristics. In Chapter 5, an X-band radar frequency modulated continuous wave generator has been designed. Based on the X-band frequency synthesizer in Chapter 4, the delta-sigma modulator and digital modulation are added to generate FMCW performance. Using counter counts up and down to switch the delta-sigma modulator. The delta-sigma modulator can switch the division ratio of the multi-mode frequency divider, and the low-pass filter can generate a periodic charge and discharge in order to achieve a triangular wave output.