Dual-mode voltage-controlled oscillator
First Claim
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1. An apparatus, comprising:
- a center-tapped transformer having a primary coil and a secondary coil disposed in parallel to the primary coil;
a variable capacitance connected in parallel with the secondary coil, with the secondary coil disposed in between the variable capacitance and the primary coil; and
another capacitance connected in parallel with the primary coil, with the primary coil disposed in between the other capacitance and the secondary coil, wherein the other capacitance is either fixed or variable.
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Abstract
A novel form of an integrated variable inductor uses an on-chip transformer together with a variable capacitor. The variable capacitor can either be a varactor or a switched capacitor array and is connected to the secondary coil of the transformer. By changing the capacitance at the secondary coil of a transformer, the equivalent inductance looking into the primary coil of the transformer can be adjusted. With another capacitor in parallel to the primary coil, two different modes of resonance inherently exist, and a very wide frequency tuning range can be achieved by combining the two modes.
16 Citations
28 Claims
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1. An apparatus, comprising:
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a center-tapped transformer having a primary coil and a secondary coil disposed in parallel to the primary coil; a variable capacitance connected in parallel with the secondary coil, with the secondary coil disposed in between the variable capacitance and the primary coil; and another capacitance connected in parallel with the primary coil, with the primary coil disposed in between the other capacitance and the secondary coil, wherein the other capacitance is either fixed or variable. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A voltage-controlled oscillator, comprising
a center-tapped transformer having a primary coil configured to receive inputs and a secondary coil configured to generate outputs, wherein: -
the secondary coil is disposed in parallel to the primary coil; a variable capacitance is connected in parallel to the secondary coil, with the secondary coil disposed in between the variable capacitance and the primary coil; another capacitance that is either fixed or variable is connected in parallel with the primary coil, with the primary coil disposed in between the other capacitance and the secondary coil; the secondary coil has a first terminal at a first terminating end of the secondary coil and a second terminal at a second terminating end of the secondary coil; and the first and second terminals are the only terminals of the secondary coil. - View Dependent Claims (13, 14, 15, 16, 17, 18)
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19. An apparatus, comprising:
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a variable center-tapped transformer having a primary coil and a secondary coil disposed in parallel to the primary coil; a capacitance connected in parallel with the secondary coil, with the secondary coil disposed in between the capacitance and the primary coil; and another capacitance, either variable or fixed, in parallel with the primary coil, with the primary coil disposed in between the other capacitance and the secondary coil; wherein the secondary coil has a first terminal at a first terminating end of the secondary coil and a second terminal at a second terminating end of the secondary coil. - View Dependent Claims (20, 21, 22, 23, 24, 25)
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26. A voltage-controlled oscillator, comprising:
a center-tapped transformer having a first variable inductor and a second variable inductor that are symmetrically coupled with each other, wherein each of the variable inductors includes; a primary coil configured to receive inputs; a secondary coil configured to generate outputs and disposed in parallel to the primary coil; a variable capacitance connected in parallel to the secondary coil and disposed in between the variable capacitance and the primary coil; another capacitance connected in parallel with the primary coil and disposed in between the other capacitance and the secondary coil. - View Dependent Claims (27, 28)
Specification