Granted Patent B2

US 12,580,544 · App. 17/733,936 · Granted Mar 17, 2026

Inventor: Jorgen Staal Nielsen (Calgary, CA)

Assignee: Anlotek Limited

H03H7/00H03H11/1208H03H11/1291

Abstract

Claims (83)

1 . An active feedback RF resonator, comprising:

a signal loop having a signal input and a signal output, the signal loop comprising a variable gain stage and at least one variable resonator, each variable resonator comprising an inductance element and a variable capacitance element comprising a plurality of switched fixed value capacitors and a variable capacitor; and

a controller programmed to operate each of the plurality of switched fixed value capacitors and the variable capacitor, the variable capacitance element being operated within an operating range that is less than a maximum tunable range of the variable capacitor such that a phase noise of an active feedback RF signal is maintained below a maximum value.

2 . The active feedback RF resonator of claim 1 , wherein the phase noise is described by a relationship:

ℒ

⁡

(

Δω

)

≈

Q

2

(

r

2

M

)

2

⁢

S

Vb

(

Δ

⁢

ω

)

where Δ ω is a frequency offset from the operating frequency ω 0 , £ (Δ ω ) is the phase noise at Δ ω , Q is an operating Q of the variable resonator, r is a normalized rate of change of variable capacitance relative to an operating bias voltage of the variable capacitor, M is the number of switched fixed value capacitors, and S vb (Δ ω ) is a power spectral density of the phase noise at the operating frequency plus Δ ω .

3 . The active feedback RF resonator of claim 1 , wherein the variable capacitor is a varactor.

4 . The active feedback RF resonator of claim 1 , operating as an RF filter or an RF oscillator.

5 . A method of designing an active feedback RF resonator, comprising the steps of:

providing a signal loop having a signal input and a signal output, the signal loop comprising a variable gain stage and at least one variable resonator, each variable resonator comprising an inductance element and a variable capacitance element comprising a number of switched capacitors and a variable capacitor, the switched capacitors having fixed capacitance values; and

for each variable resonator:

calculating an operating factor based on one or more of the following parameters of the variable resonator: a minimum Q, a maximum phase noise factor, a range of operating frequencies, and an operating bias voltage and capacitance of the variable capacitor; and;

calculating the number of switched capacitors based on a logarithm of the operating factor.

6 . The method of claim 5 , wherein the operating factor is proportional to

Q

⁢

r

⁢

S

Vb

(

Δ

⁢

ω

)

ℒ

⁡

(

Δω

)

,

where (Δ ω ) is a frequency offset from the operating frequency, £ (Δ ω ) is the phase noise at Δ ω , Q is an operating Q of the variable resonator, r is a normalized rate of change of capacitance relative to a change in the operating bias voltage of the variable capacitor, and S vb (Δ ω ) is a power spectral density of the phase noise at Δ ω .

7 . The method of claim 5 , wherein the variable capacitor is a varactor.

8 . The method of claim 5 , wherein the active feedback RF resonator is operated as an RF filter or an RF oscillator.

9 . An active feedback RF resonator, comprising:

a signal loop having a signal input and a signal output, the signal loop comprising a variable gain stage and at least one variable resonator, each variable resonator comprising an inductance element and a variable capacitance element comprising a number of switched capacitors and a variable capacitor, the switched capacitors having fixed capacitance values, and wherein the variable capacitor comprises 40% or less of a total capacitance of the variable capacitance element.

10 . The active feedback RF resonator of claim 9 , wherein the variable capacitor comprises 20% or less of the total capacitance of the variable capacitance element.

11 . The active feedback RF resonator of claim 9 , wherein the variable capacitor is a varactor.

12 . The active feedback RF resonator of claim 9 , wherein the phase noise is described by a relationship:

ℒ

⁡

(

Δω

)

≈

Q

2

(

r

2

M

)

2

⁢

S

Vb

(

Δ

⁢

ω

)

where Δ ω is a frequency offset from the operating frequency ω 0 , £ (Δ ω ) is the phase noise at Δ ω , Q is an operating Q of the variable resonator, r is a normalized rate of change of variable capacitance relative to an operating bias voltage of the variable capacitor, M is the number of switched fixed value capacitors, and S vb (Δ ω ) is a power spectral density of the phase noise at the operating frequency plus Δ ω .

Assignments (1)

Continuity (2)

References Cited (132)