Broadband Low Phase Noise Vco Design And Production

With the development of wideband communication technology, the demand for wideband VCO grows heavily. Because the wideband voltage-controlled oscillator which using the varactor diode as a tuning device has the advantage of small size, low cost, flexible design, it represent a significant proportion at wideband voltage-controlled oscillators. The goal of this subject is to conclude technique to produce low phase wideband VCOs, through studying the basic theory and the fruit in and abroad, combining with the actual situation. Using high Q components, such as: coaxial resonator, dielectric resonator, makes bandwidth of VCO become narrower, so that recently common wideband VCOs make inductor and capacitor (LC) as resonators, combing varactors with wide range tunable capacitance, and achieve the wideband.Normally, the wider the band is, the lower the Q is. There is some relationship between phase noise of oscillator and Q of resonator. The lower the Q is, the worse the phase noise is. The goal of this subject is to produce a wideband voltage-controlled oscillator which works in 4~7GHz. To get wide band and good phase noise, we divide it into three sections: 4~5GHz, 5~6GHz, 6~7GHz.The finished VCO, its phase noise features are very good. At the conditions of free oscillation (not in PLL), the phase noise in every frequency range has achieved -90 dBc/Hz@20kHz. At 4.8GHz, the phase noise is about -90dBc/Hz@20kHz ,-95dBc/Hz@100kHz; At 5 GHz, the phase noise is about 89dBc/Hz@38kHz,-99dBc/Hz@77kHz.