| Summary: | 碩士 === 國立東華大學 === 電機工程學系 === 104 === For wireless communication systems, voltage controlled oscillators (VCOs) are important parts in RF transceivers, especially for the frequency synthesizers. VCO is used to generate a local oscillation (LO) signal which provided for frequency mixing in mixer design. In this thesis, a low power VCO is presented for the application of the Ka-band satellite systems. The VCO chip was fabricated by tsmc 180nm 1P6M CMOS process.
The proposed low-power VCO is designed using a fourth-order resonator. The cross-coupled transistors generate a negative impedance to cancel out the parasitic resistance in an LC resonator. The threshold voltage of the MOSFET can be reduced by the body-biased technique to lower the supply voltage. Finally, the presented VCO is based on the structure of a Colpitts oscillator which can improve the phase noise.
The simulation results show the oscillation frequency from 37.74GHz to 41.63GHz corresponding to a tuning range of 9.7%. The output power is -9.33dBm. The power consumption of the VCO core is 8.62mW at a supply voltage of 0.9V. The phase noise is -102.84dBc/Hz at 1MHz offset frequency. As seen from the measurement results, one of the inductors is considered as a signal line and is not function as an inductor. Hence, the ideal oscillation frequency of 40GHz can not be obtained. The measurement oscillation frequency is from 24.09GHz to 26.33GHz. Output power is -17.78dBm. Power consumption of the VCO core is 13.5mW at a supply voltage of 1.1V. The phase noise is -86.56dBc/Hz at 1MHz offset frequency.
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