TANK CIRCUIT OF PHASE LOCKED LOOP OSCILLATOR

摘要

PURPOSE: A tank circuit of a phase locked loop oscillator is provided which reduces the number of component devices constructing the tank circuit and shortens a pattern length, to decrease material costs and improve phase noise characteristic. CONSTITUTION: A tank circuit(22) of a phase locked loop oscillator(21) is coupled to the phase locked loop oscillator through coupling capacitors(C1,C2). The tank circuit provides capacitance of a varactor diode(D1) according to a tuning voltage(VT). The tank circuit is constructed in a manner that a switching diode(D0) is switched according to a select voltage to provide a resonant frequency corresponding to VHF-high band and VHF-low band to the phase locked loop oscillator.