# US 2013/0154752 A1 · Voltage-controlled oscillator

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 2013/0154752 A1
- Document ID: US20130154752A1
- Status: Published application
- Kind: A1
- Application number: 13/325,442
- Filed: 2011-12-14
- Published: 2013-06-20
- Earliest claimed: 2011-12-14
- Assignees: Taiwan Semiconductor Manufacturing Company, Ltd.
- Inventors: Ying-Ta LU; Hsien-Yuan LIAO; Hsiao-Tsung YEN; Ho-Hsiang CHEN; Chewn-Pu JOU
- Web page: https://patentgrep.com/patent/US20130154752A1

## CPC

- H03B 5/1228: {the amplifier comprising one or more field effect transistors}
- H03B 5/1212: {the amplifier comprising a pair of transistors, wherein an output terminal of each being connected to an input terminal of the other, e.g. a cross coupled pair}
- H03B 5/124: {the means comprising a voltage dependent capacitance}
- H03B 5/1852: {the semiconductor device being a field-effect device}
- H03B: GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS (generators adapted for electrophonic musical instruments G10H; masers or lasers H01S; generation of oscillations in plasma H05H)

## Abstract

A voltage-controlled oscillator circuit includes a first transistor, a second transistor, a first resonator circuit, a second resonator circuit, a first current path and a second current path. A drain of the first transistor is coupled to a gate of the second transistor and to a first end of the first resonator circuit. A source of the first transistor is coupled to the first current path and to a first end of the second resonator circuit. A drain of the second transistor is coupled to a gate of the first transistor and to a second end of the first resonator circuit. A source of the second transistor is coupled to the second current path and a second end of the second resonator circuit.

## Claims

### Claim 1

A voltage-controlled oscillator (VCO) circuit comprising:
a first transistor;
a second transistor;
a first resonator circuit;
a second resonator circuit;
a first current path; and
a second current path,
wherein
a drain of the first transistor is coupled to a gate of the second transistor and to a first end of the first resonator circuit;
a source of the first transistor is coupled to the first current path and to a first end of the second resonator circuit;
a drain of the second transistor is coupled to a gate of the first transistor and to a second end of the first resonator circuit; and
a source of the second transistor is coupled to the second current path and to a second end of the second resonator circuit.

### Claim 2 (depends on 1)

The VCO circuit of claim 1, further comprising:
a third transistor; and
a fourth transistor,
wherein
a drain of the third transistor is coupled to a gate of the fourth transistor and to the first end of the first resonator circuit; and
a drain of the fourth transistor is coupled to a gate of the third transistor and to the second end of the first resonator circuit.

### Claim 3 (depends on 2)

The VCO circuit of claim 2, wherein
the first transistor and the second transistor are N-type metal-oxide semiconductor (NMOS) transistors, and the third transistor and the fourth transistor are P-type metal-oxide semiconductor (PMOS) transistors; or
the first transistor and the second transistor are PMOS transistors, and the third transistor and the fourth transistor are NMOS transistors.

### Claim 4 (depends on 1)

The VCO circuit of claim 1, wherein
the first current path and/or the second current path is formed by a transistor or a current source.

### Claim 5 (depends on 1)

The VCO circuit of claim 1, wherein
the second resonator circuit is configured to provide low impedance at a oscillation frequency of VCO circuit and provide high impedance at a low frequency, a flicker frequency, and/or a 2nd harmonic frequency of the VCO circuit.

### Claim 6 (depends on 1)

The VCO circuit of claim 1, wherein
the second resonator circuit is configured to serve as an electrically short circuit at an oscillation frequency of the VCO circuit and serve as an electrically open circuit at a low frequency, a flicker frequency, and/or a 2nd harmonic frequency of the VCO circuit.

### Claim 7 (depends on 1)

The VCO circuit of claim 1, wherein
the second resonator circuit includes at least one capacitive device and at least one inductive device;
an effective capacitance of the at least one capacitive device is electrically coupled in series with an effective inductance of the at least one inductive device; and
if ωosc represents an angle oscillation frequency of the VCO circuit, Leff represents the effective inductance, and Ceff represents the effective capacitance, then the second resonator circuit is configured to satisfy the following equation:
ω
osc
=
1
Leff
·
Ceff

### Claim 8 (depends on 1)

The VCO circuit of claim 1, wherein
the second resonator circuit includes at least one transmission line coupled with at least one capacitive device;
if TCeff represents an effective capacitance of the at least one capacitive device, Zc represents the effective impedance of the effective capacitance, fosc represents an oscillation frequency of the VCO circuit, Zpred represents a predetermined impedance, t represents a mathematical constant, then the second resonator circuit is configured to satisfy the following equations:
Zc
=
1
2

π
·
fosc
·
TCeff
≤
Zpred
and
if an effective length of the at least one transmission line is λ/2, λ represents a wavelength of the oscillation frequency, Vp represents a propagation velocity, c(light) represents the speed of light in vacuum, ε0 represents a permittivity of free space, εr represents a relative permittivity, and εeff represents an effective permittivity, the second resonator circuit is configured to satisfy the following equations:
Vp
=
c

(
light
)
ɛ
eff
ɛ
eff
=
ɛ
0
·
ɛ
r
Vp
=
fosc
·
λ
.

### Claim 9 (depends on 8)

The VCO circuit of claim 8, wherein
the at least one capacitive device includes a first capacitive device and a second capacitive device; and
the at least one transmission line is coupled between the first capacitive device and the second capacitive device.

### Claim 10

A method comprising:
determining an oscillation frequency of a first resonator circuit of a voltage-controlled oscillator (VCO) circuit;
determining a first current and a second current flowing in the VCO circuit;
providing a first current path and a second current path for the VCO circuit;
providing a second resonator circuit, a first end of the second resonator circuit coupled to the first current path, a second end of the second resonator coupled to the second current path,
wherein
the first resonator circuit and the second resonator circuit cause the VCO circuit to oscillate at a first operational condition of the VCO circuit;
at a second operational condition of the VCO circuit, the first current path is for use by the first current and the second current path is for use by the second current.

### Claim 11 (depends on 10)

The method of claim 10, wherein
the first current path and/or the second current path is formed by a current source or a transistor.

### Claim 12 (depends on 10)

The method of claim 10 wherein
the first current path and the second current path are formed by a respective first transistor and second transistor;
a gate of the first transistor and a gate of the second transistor are coupled together and configured to receive a control voltage;
a drain of the first transistor is coupled to the first end of the second resonator circuit and a drain of the second transistor is coupled to the second end of the second resonator circuit.

### Claim 13 (depends on 10)

The method of claim 10, wherein
the first operational condition of the VCO circuit occurs when the second resonator circuit provides an impedance lower than that of a transmission line; and
the second operational condition of the VCO circuit occurs when the second resonator circuit provides an impedance higher than that of the transmission line.

### Claim 14 (depends on 10)

The method of claim 10, wherein
the second resonator circuit comprises at least one capacitive device and at least one inductive device;
an effective capacitance of the at least one capacitive device is electrically coupled in series with an effective inductance of the at least one inductive device;
if ωosc represent an angle oscillation frequency of the VCO circuit, Ceff represents a value of the effective capacitance, and Leff represents a value of the effective inductance, then
ω
osc
=
1
Leff
·
Ceff

### Claim 15 (depends on 10)

The method of claim 10, wherein
the second resonator circuit includes at least one transmission line coupled with at least one capacitive device;
if TCeff represents an effective capacitance of the at least one capacitive device, Zc represents the effective impedance of the effective capacitance, fosc represents an oscillation frequency of the VCO circuit, Zpred represents a predetermined impedance, it represents a mathematical constant, then the second resonator circuit is configured to satisfy the following equation:
Zc
=
1
2

π
·
fosc
·
TCeff
≤
Zpred
and
if an effective length of the at least one transmission line is λ/2, λ represents a wavelength of the oscillation frequency, Vp represents a propagation velocity, c(light) represents the speed of light in vacuum, ε0 represents a permittivity of free space, εr represents a relative permittivity, and εeff represents an effective permittivity, the second resonator circuit is configured to satisfy the following equations:
Vp
=
c

(
light
)
ɛ
eff
ɛ
eff
=
ɛ
0
·
ɛ
r
Vp
=
fosc
·
λ

### Claim 16 (depends on 15)

The circuit of claim 15, wherein
the at least one capacitive device includes a first capacitive device and a second capacitive device; and
the at least one transmission line is coupled between the first capacitive device and the second capacitive device.

### Claim 17

A method comprising:
causing a first resonator circuit of a voltage-controlled oscillator (VCO) circuit to provide an oscillation frequency for the VCO circuit;
causing a second resonator circuit to serve as an electrical short circuit at the oscillation frequency of the VCO circuit; and
at a frequency different from the oscillation frequency of the VCO circuit,
causing the second resonator circuit to serve as an electrical open circuit,
causing a first current of the VCO circuit to flow through a first current path of the VCO, and
causing a second current of the VCO circuit to flow through a second current path of the VCO circuit,
wherein
the first current is different from the second current; and
the first current path is different from the second current path.

### Claim 18 (depends on 17)

The method of claim 17, wherein
the second resonator circuit comprises at least one capacitive device and at least one inductive device;
an effective capacitance of the at least one capacitive device is electrically coupled in series with an effective inductance of the at least one inductive device;
if ωosc represent an angle oscillation frequency of the VCO circuit, Ceff represents a value of the effective capacitance, and Leff represents a value of the effective inductance, then
ω
osc
=
1
Leff
·
Ceff

### Claim 19 (depends on 17)

The method of claim 17, wherein
the second resonator circuit includes at least one transmission line coupled with at least one capacitive device;
if TCeff represents an effective capacitance of the at least one capacitive device, Zc represents the effective impedance of the effective capacitance, fosc represents an oscillation frequency of the VCO circuit, Zpred represents a predetermined impedance, π represents a mathematical constant, then the second resonator circuit is configured to satisfy the following equation:
Zc
=
1
2

π
·
fosc
·
TCeff
≤
Zpred
and
if an effective length of the at least one transmission line is λ/2, λ represents a wavelength of the oscillation frequency, Vp represents a propagation velocity, c(light) represents the speed of light in vacuum, ε0 represents a permittivity of free space, εr represents a relative permittivity, and εeff represents an effective permittivity, the second resonator circuit is configured to satisfy the following equations:
Vp
=
c

(
light
)
ɛ
eff
ɛ
eff
=
ɛ
0
·
ɛ
r
Vp
=
fosc
·
λ
.

### Claim 20 (depends on 19)

The circuit of claim 19, wherein
the at least one capacitive device includes a first capacitive device and a second capacitive device; and
the at least one transmission line is coupled between the first capacitive device and the second capacitive device.