A new design of the RF oscillator for the UHF-band is presented. In order to get a higher Q value,a multi-ple frequency selection network is used,which is composed by both series components and parallel components. For this RF oscillator,the operating frequency range is 400 MHz~720 MHz,with a 300 MHz relative bandwidth. The test results show that,in the available frequency range,the fluctuations of the output power is less than 1 dB,input VSWR<1.5 dB,output VSWR<1.7 dB;When the carrier frequency is 510 MHz,the phase noise PN=-77.9 dBc/Hz,atΔf=1 kHz;phase noise PN=-95.8 dBc/Hz,at Δf=10 kHz;phase noise PN=-140.3 dBc/Hz,atΔf=100 kHz. If the fre-quency deviation is on the increase,the value of the phase noise will decreases exponentially. This RF oscillator can be widely used in many UHF devices and products,such as the TV system,the wireless intercom system,the remote control system etc.%基于反馈式正弦波振荡器原理,设计出一款适合于UHF波段的高稳频型射频振荡器,本设计使用了高Q值选频技术,利用回路的谐振特性设计出多级的选频结构。振荡器输出频率范围：400 MHz~720 MHz,输出带宽大于300 MHz,属宽带射频振荡器。测试结果表明,在可用频段范围内,振荡器输出增益波动低于1 dB,输入驻波比VSWR<1.5 dB,输出驻波比VSWR<1.7 dB；中心频率f0=510 MHz时：频偏Δf=1 kHz处,相位噪声PN=-77.9 dBc/Hz；频偏Δf=10 kHz处,相位噪声PN=-95.8 dBc/Hz；频偏Δf=100 kHz处,相位噪声PN=-140.3 dBc/Hz；当频偏继续增加时,相位噪声呈指数下降。本设计可满足电视系统、无线对讲机系统、无线遥控系统等多种主流射频领域的应用要求。
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