Abstract: The voltage controlled oscillator contains a circuit board having a laminate of a plurality of insulating plates, a wiring pattern formed on a surface of the circuit board, an electronic part mounted on the surface of the circuit board, a resonance strip line provided on an inner layer of the circuit board, and a ground pattern formed on an inner layer of the circuit board which is disposed between the wiring pattern and the strip line. Further, a conductor-deleted portion of the ground pattern faces the vicinity including a portion having a high current density in the strip line. Thus, reductions of inductance and Q are small. In addition, a portion of the strip line is shielded by means of the ground pattern with respect to the wiring pattern.

Abstract: The voltage controlled oscillator contains a circuit board having a laminate of a plurality of insulating plates, a wiring pattern formed on a surface of the circuit board, an electronic part mounted on the surface of the circuit board, a resonance strip line provided on an inner layer of the circuit board, and a ground pattern formed on an inner layer of the circuit board which is disposed between the wiring pattern and the strip line. Further, a conductor-deleted portion of the ground pattern faces the vicinity including a portion having a high current density in the strip line. Thus, reductions of inductance and Q are small. In addition, a portion of the strip line is shielded by means of the ground pattern with respect to the wiring pattern.

Abstract: A voltage controlled oscillator comprises an oscillation transistor, a varactor diode, a resonance circuit which is coupled to the oscillation transistor, and a switching diode which changes over a resonance frequency of the resonance circuit, wherein the resonance circuit includes a first strip conductor which is served for grounding a cathode of the varactor diode in terms of direct current and a second strip conductor which is served for coupling a cathode of the varactor diode with the oscillation transistor, the switching diode is connected to the first strip conductor in parallel in terms of high frequency and has a cathode thereof grounded, and a control voltage which is served for changing a capacitive value of the varactor diode is applied to a connection point between the cathode of the varactor diode and the second strip conductor through a choke inductor.

Abstract: A voltage controlled oscillator comprises an oscillation transistor, a varactor diode, a resonance circuit which is coupled to the oscillation transistor, and a switching diode which changes over a resonance frequency of the resonance circuit, wherein the resonance circuit includes a first strip conductor which is served for grounding a cathode of the varactor diode in terms of direct current and a second strip conductor which is served for coupling a cathode of the varactor diode with the oscillation transistor, the switching diode is connected to the first strip conductor in parallel in terms of high frequency and has a cathode thereof grounded, and a control voltage which is served for changing a capacitive value of the varactor diode is applied to a connection point between the cathode of the varactor diode and the second strip conductor through a choke inductor.

Abstract: In a three-band switching oscillator, a switching circuit is provided to switch the operating conditions of a first and second voltage-controlled oscillator and to switch an oscillation frequency band of the first voltage-controlled oscillator. The switching circuit switches a first switch in accordance with a switching voltage inputted to a first switching terminal and switches an oscillation frequency band in accordance with a switching voltage inputted to a second switching terminal. Only when a high-level switching voltage is inputted to the second switching terminal, the second switch is placed into an open condition by a high-level switching voltage inputted to the first switching terminal and placed into a closed condition by a low-level switching voltage inputted thereto, and when a low-level switching voltage is inputted to the second switching terminal, the second switch is placed into the open condition irrespective of the switching voltage inputted to the first switching terminal.

Abstract: The frequency-characteristic switchable buffer circuit includes an amplifying stage, a parallel resonance circuit which serves as an output load of the amplifying stage, a frequency trap circuit electrically connected between the input of the amplifying stage and a reference potential point, and a frequency switching voltage generator for selectively generating a first switching voltage or a second switching voltage. The parallel resonance circuit parallel-resonates at a first frequency when the first switching voltage is supplied thereto. When the second switching voltage is supplied thereto, the parallel resonance circuit parallel-resonates at a second frequency. The frequency trap circuit comprises a series circuit made up of a diode and a capacitor. When the first switching voltage is supplied to the frequency trap circuit, the frequency trap circuit series-resonates at a frequency lower than the first frequency.

Abstract: In a three-band switching oscillator, a switching circuit is provided to switch the operating conditions of first and second voltage-controlled oscillator and to switching an oscillation frequency band of said first voltage-controlled oscillator, and is composed of a first switch for supplying a current to place the first voltage-controlled oscillator into operation, a second switch for supplying a current to place the second voltage-controlled oscillator into operation, and first and second switching terminals for receiving switching voltages.

Abstract: The high frequency tuning amplifier for buffer has a tuning circuit consisting of a serial circuit of the first and second inductors connected between the output of transistor amplifying stage and the power source, a first capacitor connected in parallel to the serial circuit of first and second inductors, a serial circuit of the second and third capacitors connected in parallel to the second inductor and a switching element to which a band switch voltage is supplied, connected between the connecting point of the second and third capacitors and the reference voltage point. The tuning circuit is tuned to the high band frequency when the switching element is turned ON and to the low band frequency when the switching element is turned OFF.