چكيده به لاتين
In the microwave regime, the oscillator is mainly employed to produce a communication signal. many radar systems need a low phase noise oscillator. It can then be treated as a local-oscillating (LO) signal generator for performing in an up-conversion and down-conversion system, or it can be applied to be a microwave source in a radar system.
It is difficult to design tunable SIW resonators but recently some are reported and we decide to improve phase noise parameter and tunning range of oscillator.
In this paper, an -band low phase-noise voltagecontrolled oscillator (VCO) using a novel electronically tunable substrate integrated waveguide (SIW) resonator is proposed and developed for RF/microwave applications on the basis of the substrate integrated circuits concept. In this case, the resonant frequency of the SIW cavity resonator is tuned by different dc-biasing voltages applied over a varactor coupled to the cavity. Measured results show that the tuning range of the resonator is about 400 MHz for DC-bias Variations and 500 MHz by flap. Subsequently, a novel negative-resistance low phase noise VCO is developed by taking advantage of the proposed tunable resonator. Measured results demonstrate a frequency tuning range of 630 MHz and a phase noise of -115 dBc/Hz at a 100-kHz and a phase noise of -135 dBc/Hz at a 1 MHz offset over all oscillation frequencies. The VCO is also able to deliver an output power from 10.32 to 10.76 dBm. This type of VCO is very suitable for low-cost microwave and millimeter-wave applications.
Keywords: voltage-controlled oscillator (VCO), phase noise, tunable resonator, substrate integrated waveguide (SIW).
