Voltage controlled oscillator

1. An oscillator comprising:

a first resonance circuit including a first variable capacitance diode having a cathode connected to a control terminal, a first capacitor and a first inductor directly connected between an anode of the first variable capacitance diode and ground respectively;

a second resonance circuit including a second variable capacitance diode having a cathode connected to the control terminal, a second capacitor and a second inductor directly connected between an anode of the second variable capacitance diode and ground respectively; and

an oscillation circuit coupled to the first and second resonance circuits and outputting an oscillation output.

2. The oscillator as claimed in claim 1 , wherein the oscillation circuit includes:

a bipolar transistor; and

third and fourth capacitors connected in series between the base of the bipolar transistor and ground,

a node between the third and fourth capacitors being connected to an emitter of the bipolar transistor.

3. The oscillator as claimed in claim 2 , further comprising a resistor connected between the node and the emitter.

4. The oscillator as claimed in claim 1 , wherein:

the oscillation circuit has a bipolar transistor;

the oscillator comprises a buffer circuit coupled between a collector of the bipolar transistor and an output terminal.

5. The oscillator as claimed in claim 1 , wherein:

the oscillation circuit has a bipolar transistor; and

the oscillator comprises a feedback circuit coupled between an emitter and a base of the bipolar transistor.

6. An oscillator comprising:

a first resonance circuit including a first variable capacitance diode having a cathode connected to a control terminal, a first capacitor and a first inductor connected between an anode of the first variable capacitance diode and ground;

a second resonance circuit including a second variable capacitance diode having a cathode connected to the control terminal, a second capacitor and a second inductor connected between an anode of a second variable capacitance diode and ground;

an oscillation circuit coupled to the first and second resonance circuits and outputting an oscillation output;

a first coupling capacitor coupling the first resonance circuit and the oscillation circuit; and

a second coupling capacitor coupling the second resonance circuit and the oscillation circuit,

wherein the first coupling capacitor and the second coupling capacitor are coupled in parallel.

7. The oscillator as claimed in claim 6 , wherein:

the first coupling capacitor has a capacitance less than that of the second coupling capacitor; and

the first capacitor and the first inductor have a capacitance and an inductance that are respectively greater than a capacitance of the second capacitor and an inductance of the second inductor.

8. An oscillator comprising:

a first resonance circuit including a first variable capacitance diode having a cathode connected to a control terminal, a first capacitor and a first inductor connected between an anode of the first variable capacitance diode and ground;

a second resonance circuit including a second variable capacitance diode having a cathode connected to the control terminal, a second capacitor and a second inductor connected between an anode of a second variable capacitance diode and ground;

an oscillation circuit coupled to the first and second resonance circuits and outputting an oscillation output;

a first coupling capacitor coupling the first resonance circuit and the oscillation circuit; and

a second coupling capacitor coupling the second resonance circuit and the oscillation circuit, wherein:

the oscillation circuit includes a bipolar transistor;

the first coupling capacitor is connected between the anode of the first variable capacitance diode and the base of the bipolar transistor; and

the second coupling capacitor is connected between the anode of the second variable capacitance diode and the base of the bipolar transistor.

9. An oscillator comprising:

a resonance circuit having a variable capacitance diode having a cathode connected to a control terminal, a first capacitor and a first inductor directly connected between an anode of the variable capacitance diode and ground respectively, and a second capacitor directly connected between a cathode of the variable capacitance diode and ground respectively;

an oscillation circuit outputting an oscillation signal;

a first coupling capacitor coupling the resonance circuit and the oscillation circuit; and

a second coupling capacitor coupling the resonance circuit and the oscillation circuit,

wherein the first coupling capacitor and the second coupling capacitor are coupled in parallel.

10. The oscillator as claimed in claim 9 , wherein the first coupling capacitor has a capacitance less than that of the second coupling capacitor.

11. An oscillator comprising:

a resonance circuit having a variable capacitance diode having a cathode connected to a control terminal, a first capacitor and a first inductor connected between an anode of the variable capacitance diode and ground, and a second capacitor connected between a cathode of the variable capacitance diode and ground;

an oscillation circuit outputting an oscillation signal;

a first coupling capacitor coupling the resonance circuit and the oscillation circuit; and

a second coupling capacitor coupling the resonance circuit and the oscillation circuit, wherein:

the oscillation circuit has a bipolar transistor;

the first coupling capacitor is connected between the anode of the variable capacitance diode and a base of the bipolar transistor; and

the second coupling capacitor is connected between the cathode of the variable capacitance diode and the base of the bipolar transistor.