VOLTAGE CONTROLLED VARIABLE TUNNING CIRCUIT FOR SWITCHOVER OF OSCILLATION FREQUENCY BAND IN VOLTAGE CONTROLLED OSCILLATOR

摘要

PURPOSE: A voltage controlled variable tuning circuit for converting an oscillating frequency bandwidth of a voltage controlled oscillator(VCO) is provided, which is operated at high frequency bandwidth without changing inductor length by varying capacitance. CONSTITUTION: A voltage controlled variable tuning circuit(24) for converting an oscillating frequency bandwidth of a VCO(voltage controlled oscillator) includes the first capacitor(20) connected between an oscillating circuit(16) and a control voltage terminal(14) for inputting a control voltage for varying the oscillating frequency, a variable capacitance device connected between the control voltage terminal(14) and a reference voltage, an inductor(22) connected to the variable capacitance device in parallel and the second capacitor(26). The voltage controlled variable tuning circuit(24) further includes a frequency bandwidth conversion circuit(30) for selectively connecting the first capacitor(20) to the second capacitor(26) in parallel in response to the frequency bandwidth.