Design of Low Phase Noise Current-Reused VCO and Double-Balanced Mixer with Low Power and High Gain

• Main Authors: Chiu, Po-Ju, 邱柏儒
• Other Authors: Jou, Christina-F.
• Format: Others
• Language: en_US
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/77699149475831248901

碩士 === 國立交通大學 === 電信工程研究所 === 100 === This thesis consists of three parts. All the proposed circuits were implemented in TSMC 0.18μm mixed-signal/RF CMOS 1P6M technology. Part I presents a low phase noise current-reused VCO (CR-VCO). Owning to the conventional current-reused VCO (CR-VCO) needs a high capacitance external capacitor (Cgnd) to connect the source terminals of the transistors (20PF up). By connecting the Cgnd with an inductance in series, the capacitance of Cgnd will not only largely decrease from 20PF to 1PF, but also it could fully integrate in a single chip without adding an external capacitor. According to the measured results, the oscillation frequency is 4.78 - 5.33GHz, and the power consumption is about 5.76mW at the supply voltage of 1.8V. The phase noise at 1MHz offset is -117.8dBc/Hz and the figure-of-merit (FOM) of the proposed VCO is about -183.78dBc/Hz. 　　Part II presents a back-gate coupled current-reused quadrature VCO (CR-QVCO) which use double feedback mechanism to accomplish modified spontaneous transconductance match (M-STM) technique. This method is able to eliminate the transconductance difference between NMOS and PMOS transistors so that high output amplitude balance can be achieved. According to the measured results, the oscillation frequency is 4.84 - 5.17 GHz, and the power consumption is about 5.04mW at the supply voltage of 1.3V. The phase noise at 1MHz offset is -117.4dBc/Hz and the figure-of-merit (FOM) of the proposed QVCO is about -184.07dBc/Hz. 　　Part III proposes a double-balanced mixer with low power and high gain. In general, active mixer could provide better conversion gain. Gilbert-cell mixer could provide better LO-IF isolation comparison with single-balanced mixer, but it needs to pay the cost of larger power consumption and noise figure. Therefore, we try to design a mixer topology with high gain and low power in this part. By adding coupling capacitors to increase the transconductance, it could enhance the conversion gain instead of increasing RL. According to the simulated results: The conversion gain of the 15GHz double-balanced mixer is 17.0dB, increasing about 4.7dB compared with the mixer without coupling capacitors. The noise figure (NF) is about 21.0 dB. And the power consumption is about 3.6 mW at the supply voltage of 1.8V