Voltage-controlled oscillators and related systems
View Patent ↗Apparatus are provided for voltage-controlled oscillators and related systems. An exemplary voltage-controlled oscillator includes an active-circuit arrangement that facilitates generation of an oscillating signal, and a resonator arrangement capacitively coupled to the active-circuit arrangement to influence an oscillation frequency of the oscillating signal based on a difference between a first control voltage and a second control voltage.
1. A voltage-controlled oscillator comprising:
a first voltage node to receive a first voltage;
a second voltage node to receive a second voltage;
a third voltage node to receive a third voltage;
an active-circuit arrangement facilitating generation of a first oscillating signal at a first output node and a second oscillating signal at a second output node, the active-circuit arrangement comprising:
a first field-effect transistor having a first drain terminal connected to the first output node, a first gate terminal connected to the second output node, and a first source terminal; and
a second field-effect transistor having a second drain terminal connected to the first gate terminal at the second output node, a second gate terminal connected to the first drain terminal at the first output node, and a second source terminal connected to the first source terminal;
a resonator arrangement coupled to the first voltage node and the second voltage node to influence an oscillation frequency for the first oscillating signal and the second oscillating signal based on a difference between the first voltage and the second voltage, the resonator arrangement including a first inductive element coupled between the second voltage node and a first node and a second inductive element coupled between the second voltage node and a second node;
a first capacitive element configured electrically in series between the first output node and the resonator arrangement;
a second capacitive element configured electrically in series between the second output node and the resonator arrangement;
a third inductive element connected between the first output node and the third voltage node; and
a fourth inductive element connected between the second output node and the third voltage node, wherein:
the resonator arrangement is capacitively coupled to the active-circuit arrangement via the first capacitive element and the second capacitive element;
each of the first capacitive element and the second capacitive element has a low impedance at the oscillation frequency; and
the third inductive element and the fourth inductive element are effectively open circuits at the oscillation frequency.
2. The voltage-controlled oscillator of claim 1 , wherein each of the first capacitive element and the second capacitive element is an effective short-circuit at the oscillation frequency.
3. The voltage-controlled oscillator of claim 1 , the third voltage biasing the active-circuit arrangement, wherein the first capacitive element and the second capacitive element isolate the resonator arrangement from the third voltage.
4. The voltage-controlled oscillator of claim 3 , wherein variations in the third voltage do not influence a range of resonant frequencies provided by the resonator arrangement.
5. The voltage-controlled oscillator of claim 1 , further comprising:
a ground voltage node to receive a ground voltage; and
a transmission line element connected between the ground voltage node and a common source node, wherein the first source terminal is connected to the second source terminal at the common source node.
6. The voltage-controlled oscillator of claim 1 , the first capacitive element being connected between the active-circuit arrangement and the first node of the resonator arrangement and the second capacitive element being connected between the active-circuit arrangement and the second node of the resonator arrangement, wherein the resonator arrangement further comprises:
a first variable capacitance element connected between the first voltage node and the first node of the resonator arrangement; and
a second variable capacitance element connected between the first voltage node and the second node of the resonator arrangement.
7. The voltage-controlled oscillator of claim 6 , wherein:
the first inductive element is connected between the second voltage node and the first node of the resonator arrangement; and
the second inductive element is connected between the second voltage node and the second node of the resonator arrangement.
8. The voltage-controlled oscillator of claim 7 , wherein:
the first variable capacitance element comprises a first varactor having its anode terminal connected to the first voltage node and its cathode terminal connected to the first node of the resonator arrangement; and
the second variable capacitance element comprises a second varactor having its anode terminal connected to the first voltage node and its cathode terminal connected to the second node of the resonator arrangement.
9. The voltage-controlled oscillator of claim 1 , further comprising:
a ground voltage node to receive a ground voltage; and
a transmission line element connected between the ground voltage node and the active-circuit arrangement, wherein the transmission line element is configured as a quarter wave impedance transformer at twice the oscillation frequency.
10. The voltage-controlled oscillator of claim 1 , wherein each of the first capacitive element and the second capacitive element has an impedance of 15Ω or less at the oscillation frequency.
11. The voltage-controlled oscillator of claim 1 , wherein each of the first capacitive element and the second capacitive element has minimal influence on the oscillation frequency.
12. The voltage-controlled oscillator of claim 1 , wherein:
the third inductive element comprises a first transmission line element connected between the first output node and the third voltage node; and
the fourth inductive element comprises a second transmission line element connected between the second output node and the third voltage node, wherein the first transmission line element and the second transmission line element are effectively open circuits at the oscillation frequency.
13. The voltage-controlled oscillator of claim 12 , further comprising:
a ground voltage node to receive a ground voltage; and
a third transmission line element connected between the ground voltage node and a common source node, wherein:
the first source terminal is connected to the second source terminal at the common source node; and
the third transmission line element is configured as a quarter wave impedance transformer at twice the oscillation frequency.
14. The voltage-controlled oscillator of claim 1 , wherein:
each of the first capacitive element and the second capacitive element has an impedance of 15Ω or less at the oscillation frequency; and
the oscillation frequency is greater than 36 GHz.
15. A voltage-controlled oscillator comprising:
a first node to receive a first voltage;
a second node to receive a second voltage;
a third node to receive a third voltage;
a first output node for a first oscillating signal;
a second output node for a second oscillating signal;
an active-circuit arrangement coupled to the first output node and the second output node to facilitate the first oscillating signal and the second oscillating signal, the active-circuit arrangement being coupled to the first node, the active-circuit arrangement comprising:
a first field-effect transistor having a first drain terminal connected to the first output node, a first gate terminal connected to the second output node, and a first source terminal; and
a second field-effect transistor having a second drain terminal connected to the first gate terminal at the second output node, a second gate terminal connected to the first drain terminal at the first output node, and a second source terminal connected to the first source terminal;
a resonator arrangement coupled to the second node and the third node, the resonator arrangement providing an oscillation frequency for the first oscillating signal and the second oscillating signal based on a voltage difference between the second voltage and the third voltage, the resonator arrangement including a first inductive element coupled between the third node and a fourth node and a second inductive element coupled between the third node and a fifth node;
a first capacitive element electrically in series between the first output node and the resonator arrangement;
a second capacitive element electrically in series between the second output node and the resonator arrangement, wherein the first and second capacitive elements are effectively short-circuits at the oscillation frequency;
a first transmission line element connected between the first node and the first output node; and
a second transmission line element connected between the first node and the second output node, wherein the first transmission line element and the second transmission line element are effectively open circuits at the oscillation frequency.
16. The voltage-controlled oscillator of claim 15 , wherein the first transmission line element and the second transmission line element are each configured as a quarter wave impedance transformer at the oscillation frequency.
17. The voltage-controlled oscillator of claim 15 , wherein the resonator arrangement includes: a first varactor connected between the second node and the fourth node, the first capacitive element being connected between the fourth node and the first output node; and a second varactor connected between the second node and the fifth node, the second capacitive element being connected between the fifth node and the second output node; and the first inductive element comprises a third transmission line element connected between the third node and the fourth node; and the second inductive element comprises a fourth transmission line element connected between the third node and the fifth node.
18. A voltage-controlled oscillator module to generate a first oscillating signal at a first output node and a second oscillating signal at a second output node, the voltage-controlled oscillator module comprising:
an active-circuit arrangement coupled to the first output node and the second output node to facilitate the first oscillating signal at the first output node and the second oscillating signal at the second output node, the active-circuit arrangement comprising:
a first field-effect transistor having a first drain terminal connected to the first output node, a first gate terminal connected to the second output node, and a first source terminal; and
a second field-effect transistor having a second drain terminal connected to the first gate terminal at the second output node, a second gate terminal connected to the first drain terminal at the first output node, and a second source terminal connected to the first source terminal;
a first transmission line element electrically in series between a first voltage node and the first output node, wherein the first transmission line element is effectively an open circuit at an oscillation frequency of the first oscillating signal;
a second transmission line element electrically in series between the first voltage node and the second output node, wherein the second transmission line element is effectively an open circuit at the oscillation frequency of the second oscillating signal;
a resonator arrangement coupled to a second voltage node and a third voltage node, the resonator arrangement influencing the oscillation frequency of the first oscillating signal and the second oscillating signal based on a voltage difference between the second voltage node and the third voltage node, the resonator arrangement including a first inductive element coupled between the second voltage node and a first node of the resonator arrangement and a second inductive element coupled between the second voltage node and a second node of the resonator arrangement;
a first capacitive element electrically in series between the first output node and the first node of the resonator arrangement, the first capacitive element having low impedance at the oscillation frequency; and
a second capacitive element electrically in series between the second output node and the second node of the resonator arrangement, the second capacitive element having low impedance at the oscillation frequency.
19. A transmitter including the voltage-controlled oscillator module of claim 18 , further comprising an antenna coupled to the voltage-controlled oscillator module to transmit an electromagnetic signal having a frequency influenced by the oscillation frequency.