Oscillator and frequency synthesizer and communication apparatus using the oscillator

Claim 2

An oscillator as claimed in claim 1, further comprising: a second output terminal, coupled to a third point where a voltage is substantially zero with respect to said oscillation frequency when said ring resonator resonates, for outputting a second harmonic frequency signal which is in phase with said second harmonic frequency signal of a second point; and an in-phase combining circuit for combining said resonant frequency signal with said second harmonic frequency signal.

Claim 3

An oscillator as claimed in claim 1 or 2, further comprising: a grounding capacitor for coupling a fourth point on said ring resonator to ground, said fourth point being apart from said first point by a half of the line length of said ring resonator.

Claim 4

An oscillator as claimed in claim 3, wherein said grounding capacitor has a capacitance equivalent to the capacitance of said oscillation circuit viewed from said first point.

Claim 5

An oscillator as claimed in claim 2, further comprising: a first grounding capacitor connected between said output terminal and ground; and a second grounding capacitor connected between said second output terminal and ground, said first ground capacitor having a capacitance which is substantially equal to a capacitance of said second ground capacitor.

Claim 6

An oscillator according to any one of the preceding claims, wherein said oscillation circuit has a control input for receiving a control signal and oscillates at said oscillation frequency controlled in accordance with said control signal.

Claim 7

An oscillator as claimed in claim 5 or 6, further comprising: a variable capacitor, having a variable capacitance, connected between said first point and a fourth point which is apart from said first point by a half of a line length of said ring resonator.

Claim 8

An oscillator as claimed in claim 5 or 6, further comprising: a first variable capacitor connected between said first point and the ground; and a second variable capacitor connected between a fourth point and the ground, said fourth point being apart from said first point by a half of a line length of said ring resonator, said first and second variable capacitor having substantially the same voltage-capacitance characteristic.

Claim 9

An oscillator as claimed in claim 5 or 6, further comprising; a third grounding capacitor connected between a fourth point and the ground, said fourth point being apart from said first point by a half of a line length of said ring resonator and the ground.

Claim 10

An oscillator as claimed in claim 9, said third grounding capacitor has a capacitance which is substantially the same as a capacitance of said oscillation circuit viewed from said first point.

Claim 11

An oscillator comprising: a ring resonator; an oscillation circuit having a negative resistance active circuit coupled to a first point on said ring resonator for oscillating at an oscillation frequency and resonating said resonator; and first and second output terminals, coupled to second and third points which are apart from said first point by the same line length along said ring resonator and are apart each other by an electrical length of 90° with respect to said oscillation frequency along said ring resonator, for outputting resonant frequency signals respectively.

Claim 12

An oscillator according to any one of claims 5-11, further comprising: a resonant capacitor connected between said first point and a fourth point which is apart from said first point by a half of a line length of said ring resonator.

Claim 13

An oscillator according to any one of claims 5-12, further comprising at least an open-end transmission line connected to at least one of said first point and a fourth point

Claim 14

An oscillator according to any one of claims 5-13, further comprising: a first grounding capacitor connected between said first point and the ground; and a second grounding capacitor connected between a fourth point and the ground, said fourth point being apart from said first point by a half of a line length of said ring resonator, said first and second grounding capacitors having substantially the same capacitance.

Claim 15

A frequency synthesizer comprising: an oscillation portion having a ring resonator and an oscillation circuit including a negative resistance active circuit coupled to said ring resonator, said oscillation circuit being coupled to a first point of said resonator, resonating said ring resonator, and generating an oscillation signal of which frequency and phase are controlled in accordance with a control signal; a phase synchronizing circuit for generating said control signal by comparing a reference signal with said oscillation signal; and an output terminal for supplying a second harmonic frequency signal from a second point on said ring resonator.

Claim 16

A frequency synthesizer as claimed in claim 15, wherein said second point on said ring resonator shows a voltage which is substantially zero with respect to said frequency of said oscillation signal when said ring resonator resonates.

Claim 17

A frequency synthesizer as claimed in claim 15 or 16, further comprising: a capacitor for coupling a fourth point on said ring resonator to the ground, said fourth point being apart from said first point by a half of the line length of said ring resonator to the ground.

Claim 18

A frequency synthesizer as claimed in claim 17, wherein said capacitor has a capacitance equivalent to a capacitance of said oscillation circuit viewed from said first point.

Claim 19

A frequency synthesizer as claimed in claim 16, 17 or 18 further comprising: a second output terminal, coupled to a third point where a voltage is substantially zero with respect to said frequency of said oscillation signal when said ring resonator resonates, for outputting a second harmonic frequency signal which is in phase with said second harmonic frequency signal at said second point; and an in-phase combining circuit for combining said resonant frequency signal with said second harmonic frequency signal.

Claim 20

A frequency synthesizer as claimed in claim 19, further comprising: a first grounding capacitor connected between said output terminal to the ground; and a second grounding capacitor connected between said second output terminal to the ground, said first capacitor having a capacitance which is substantially equal to a capacitance of said second capacitor.

Claim 21

A frequency synthesizer as claimed in claim 20, further comprising: a resonant capacitor connected between said first point and a fourth point which is apart from said first point by a half of a line length of said ring resonator.

Claim 22

A frequency synthesizer as claimed in claim 20 and 21, further comprising at least an open-end transmission line connected to at least one of said first point and a fourth point which is apart from said first point by a half of a line length of said ring resonator.

Claim 23

A frequency synthesizer as claimed in claim 20, 21 or 22, further comprising: a third grounding capacitor connected between said first point and the ground; and a fourth grounding capacitor connected between a fourth point which is apart from said first point by a half of a line length of said ring resonator, said third and fourth grounding capacitor having substantially the same capacitance.

Claim 24

A frequency synthesizer as claimed in claim 20, 21, 22 or 23 further comprising; a variable capacitor, having a variable capacitance, connected between said first point and a fourth point which is apart from said first point by a half of a line length of said ring resonator.

Claim 25

A frequency synthesizer as claimed in any one of claims 20 to 24, further comprising: a first variable capacitor connected between said first point and the ground; and a second variable capacitor connected between a fourth point and the ground, said fourth point being apart from said first point by a half of a line length of said ring resonator, said third and fourth grounding capacitors having variable capacitances and substantially the same voltage-capacitance characteristic.

Claim 26

A frequency synthesizer as claimed in claim 20, 21 or 22, further comprising; a third grounding capacitor connected between a fourth point and the ground, said fourth point being apart from said first point by a half of a line length of said ring resonator.

Claim 27

A frequency synthesizer as claimed in claim 26, said third grounding capacitor has a capacitance which is substantially the same as a capacitance of said oscillation circuit viewed from said first point.

Claim 28

An oscillator comprising: a ring resonator having a predetermined line length; a first oscillation circuit having a first negative resistance active circuit coupled to a first point on said ring resonator for oscillating at a first oscillation frequency and resonating said resonator; a second oscillation circuit having a second negative resistance active circuit coupled to a second point on said ring resonator which is apart from said first point by a quarter of said predetermined line length for oscillating at a second oscillation frequency which is different from said first oscillation frequency and for resonating said resonator; a first grounding capacitor for coupling a third point on said ring resonator to the ground, said third point being apart from said first point by a half of said predetermined line length, said first grounding capacitor having a first capacitance equivalent to a capacitance of said first oscillation circuit viewed from said first point; a second grounding capacitor for coupling a fourth point on said ring resonator to the ground, said fourth point being apart from said second point by a half of said predetermined line length, said second grounding capacitor having a second capacitance equivalent to a capacitance of said second oscillation circuit viewed from said second point; and an outputting circuit for supplying first and second outputs from said third and fourth points respectively.

Claim 29

An oscillator as claimed in claim 28, further comprising a switch for switching a supply power to either of said first or second oscillation circuit in accordance with a control signal.

Claim 30

An oscillator as claimed in claim 28 or 29, wherein said outputting circuit comprises first and second buffer amplifiers for amplifying outputs from said third and fourth points respectively and a combining circuit for combining outputs of said first and second buffer amplifiers.

Claim 31

An oscillator as claimed in claim 28, 29 or 30, further comprising at least a resonant capacitance provided to at least one of a first pair of said first and third points and a second pair of said second and fourth points.

Claim 32

An oscillator as claimed in claim 28, 29, 30 or 31, further comprising at least a pair of grounding capacitors, having substantially the same capacitance, for coupling to the ground, said at least a pair of grounding capacitors being provided to at least one of a first pair of said first and third points and a second pair of said second and fourth points respectively.

Claim 33

An oscillator as claimed in claim 32, wherein said at least a pair of grounding capacitors comprise transmission lines respectively.

Claim 34

An oscillator as claimed in any one of claims 28 to 33, further comprising at least a pair of variable capacitors, provided to at least one of a first pair of said first and third points and a second pair of said second and fourth points respectively, for coupling to the ground.

Claim 35

An oscillator as claimed in claim 34, wherein said pair of variable capacitors have substantially the same voltage-capacitance characteristic.

Claim 36

An oscillator as claimed in any one of claims 28 to 35, wherein said first and second grounding capacitors comprise transmission lines respectively.

Claim 37

An oscillator as claimed in any one of claims 28 to 36, wherein said first oscillation frequency is higher than said second oscillation frequency.

Claim 38

A communication apparatus for transmitting a first radio signal and receiving a second radio signal, comprising: an oscillator according to claim 29 or any one of claims 30 to 37 when dependent on claim 29; transmission means for transmitting said first radio signal using said first output as a carrier signal and supplying said control signal to said switch to supply said supply power to said first oscillation circuit; and receiving means for receiving said second radio signal using said second output to detect said second radio signal and supplying said control signal to said switch to supply said supply power to said second oscillation circuit.

Claim 39

A communication apparatus for receiving a radio signal, comprising: an oscillator according to any one of claims 28 to 37; receiving means for receiving said radio signal; a first frequency converting circuit for converting said radio signal from said receiving means using said first output; a second frequency converting circuit for converting an output of said first frequency converting circuit using said second output; and a detector for detecting said radio signal using an output of said second frequency converting circuit.

Claim 40

A frequency synthesizer comprising: an oscillator having: a ring resonator having a predetermined line length; a first oscillation circuit having a first negative resistance active circuit coupled to a first point on said ring resonator for resonating said resonator and oscillating at a first oscillation frequency controlled in accordance with a first control signal in a first mode; a second oscillation circuit having a second negative resistance active circuit coupled to a second point on said ring resonator which is apart from said first point by a quarter of said predetermined line length for resonating said resonator and oscillating at a second oscillation frequency controlled in accordance with a second control signal in a second mode; a first grounding capacitor for coupling a third point on said ring resonator to the ground, said third point being apart from said first point by a half of said predetermined line length, said first grounding capacitor having a first capacitance equivalent to a capacitance of said first oscillation circuit viewed from said first point; a second grounding capacitor for coupling a fourth point on said ring resonator to the ground, said fourth point being apart from said second point by a half of said predetermined line length, said second grounding capacitor having a second capacitance equivalent to a capacitance of said second oscillation circuit viewed from said second point; a switch for supplying a supply power to said first oscillation circuit in said first mode and to said second oscillation circuit in said second mode; and a phase synchronizing circuit for generating said first control signal by comparing a reference signal with said oscillation signal in said first mode and for generating said second control signal by comparing a reference signal with said oscillation signal in said second mode; and an outputting circuit for supplying first and second outputs from said third and fourth points respectively.

Claim 41

A frequency synthesizer as claimed in claim 45, wherein said first and second oscillation circuits have substantially the same frequency sensitivity such that the same change in said first and second control signals causes the same variation in said first and second oscillation frequencies.