Webb Ziesenheim Bruening Logsdon Orkin & Hanson
Voltage controlled oscillating circuit for preventing a load pulling
 A voltage controlled oscillating circuit is disclosed. The circuit includes: a .mu.-strip resonance circuit for deciding the resonance frequency in accordance with an external tuning voltage; an oscillation amplifying circuit for performing oscillations in accordance with the resonance frequency signals of the .mu.-strip resonance circuit; and a buffer amplifying circuit provided between the oscillating circuit and the load, and for preventing the load pulling phenomenon. The oscillation amplifying circuit forms a common collector oscillating circuit in with a single oscillation amplifying transistor, and the buffer amplifying circuit forms a single step amplifying circuit with a single buffer amplifying transistor. The oscillation amplifying transistor and the buffer amplifying transistor form a cascode amplifying transistor with a signal inducing coil and an RF choke coil for blocking the ac components and for forming a series of dc bias paths. Consequently, a low power consumption and a miniaturization of the voltage controlled oscillating circuit are realized, as well as a low product price. 
Samsung Electro-Mechanics Co., Ltd.
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Jung H.
Kim