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US 8,786,376 B2Granted
Varactor voltage controlled oscillator (VCO) providing independent coarse and fine frequency tuning
AssigneePeraso Technologies Inc.
InventorsSorin Voinigescu, Ekaterina Laksin
Life of this patent
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Abstract
A voltage controlled oscillator, includes a tank circuit including an inductor having a value L, interconnected with first and second variable capacitors, having values CVAR1 and CVAR2, and a fixed capacitor CFIXED, to cause oscillation of the oscillator at a controlled frequency f osc = ( 2 π ) - 1 ( L { C VAR 2 + C FIXED C VAR 1 C FIXED + C VAR 1 } ) - 1 / 2 CVAR1 controls coarse frequency tuning of the oscillator, and CVAR2 may control fine tuning of the oscillator. The variable capacitors may be formed using accumulation-mode MOS varactors.
Claims15
A voltage controlled oscillator, comprising:
- a transistor;
- a tank circuit interconnecting said transistor in feedback, said tank circuit including an inductor having a value L, interconnected with first and second variable capacitors, having values CVAR1 and CVAR2, and a fixed capacitor CFIXED, to cause oscillation of said oscillator at a controlled frequency
- f
- osc
- =
- (
- 2
-
- π
- )
- -
- 1
-
- (
- L
-
- {
- C
- VAR
-
-
- 2
- +
- C
- FIXED
-
- C
- VAR
-
-
- 1
- C
- FIXED
- +
- C
- VAR
-
-
- 1
- }
- )
- -
- 1
- /
- 2
- wherein adjustment of CVAR1 and CVAR2 control tuning of said oscillator, wherein said first variable capacitor and said fixed capacitor form a voltage divider, and wherein a node in said voltage divider interconnecting said first variable capacitor and said fixed capacitor provides feedback to said transistor;
- wherein said first variable capacitor CVAR1 is formed as a bank of parallel variable capacitors, the capacitance of each of which may be selectively adjusted by a control signal;
- wherein each capacitor of said bank of parallel variable capacitors is formed as two back-to-back connected MOS varactors.
45 more elements
A method of producing an oscillating voltage at a desired frequency, comprising:
- providing a transistor;
- providing a tank circuit interconnecting said transistor in feedback, said tank circuit including an inductor having a value L, interconnected with first and second variable capacitors, having values CVAR1 and CVAR2, and a fixed capacitor CFIXED, to cause oscillation of said transistor at a controlled frequency
- f
- osc
- =
- (
- 2
-
- π
- )
- -
- 1
-
- (
- L
-
- {
- C
- VAR
-
-
- 2
- +
- C
- FIXED
-
- C
- VAR
-
-
- 1
- C
- FIXED
- +
- C
- VAR
-
-
- 1
- }
- )
- -
- 1
- /
- 2
- adjusting CVAR1 and CVAR2 to cause oscillation at said desired frequency, wherein said first variable capacitor and said fixed capacitor form a voltage divider, and wherein a node in said voltage divider interconnecting said first variable capacitor and said fixed capacitor provides feedback to said transistor;
- wherein said first variable capacitor CVAR1 is formed as a bank of parallel variable capacitors, the capacitance of each of which may be selectively adjusted by a control signal;
- wherein each capacitor of said bank of parallel variable capacitors is formed as two back-to-back connected MOS varactors.
45 more elements
A voltage controlled oscillator, comprising:
- a transistor;
- a tank circuit interconnecting said transistor in feedback, said tank circuit including an inductor having a value L, interconnected with first and second variable capacitors, having values CVAR1 and CVAR2, and a fixed capacitor CFIXED, to cause oscillation of said oscillator at a controlled frequency
- f
- osc
- =
- (
- 2
-
-
- π
- )
- -
- 1
-
- (
- L
-
- {
- C
- VAR
-
-
- 2
- +
- C
- FIXED
-
- C
- VAR
-
-
- 1
- C
- FIXED
- +
- C
- VAR
-
-
- 1
- }
- )
- -
- 1
- /
- 2
- wherein adjustment of CVAR1 and CVAR2 control tuning of said oscillator, wherein said first variable capacitor and said fixed capacitor form a voltage divider, and wherein a node in said voltage divider interconnecting said first variable capacitor and said fixed capacitor provides feedback to said transistor;
- wherein said first variable capacitor CVAR1 is formed as a bank of parallel variable capacitors, the capacitance of each of which may be selectively adjusted by a control signal;
- wherein said second variable capacitor CVAR2 further comprises an additional bank of parallel variable capacitors, the capacitance of each of which may be selectively adjusted by a control signal;
- wherein a control signal used to control capacitance of a capacitor in said bank of capacitors forming said first variable capacitor further controls capacitance of a capacitor in said additional bank of parallel variable capacitors of said second variable capacitor.
47 more elements
Dependencies are inferred from the claim text.