Inductor structure and application thereof
The present disclosure relates to composite inductor structures for use in integrated circuits. There is provided a composite inductor structure comprising a first inductor coil and a second inductor coil. The second inductor coil comprises a multi-turn loop that surrounds the first inductor coil. The first inductor coil comprises two multi-turn loops which are connected in a figure-of-eight configuration about a central terminal so as to cause a current flowing in a first loop of the multi-turn loops to circulate around the first loop in a first rotational direction, and a current flowing in a second loop of the multi-turn loops to circulate around the second loop in a second rotational direction opposite the rotational direction of current flow in the first loop, said direction of current flow in the first and second loops being mirror images of each other.
1. A five-terminal passive device for use in integrated circuits, the device comprising:
a first inductor coil comprising
a first loop connected to a first terminal and a central terminal, and
a second loop connected to a second terminal and the central terminal,
wherein the first loop and the second loop are configured in a figure-of-eight so that a current flowing in the first inductor coil circulates around the first loop in a first rotational direction and circulates around the second loop in a second rotational direction opposite the first rotational direction; and
a second inductor coil comprising a loop that surrounds the first inductor coil,
wherein a first end of the second inductor coil connects to a third terminal,
a second end of the second inductor coil connects to a fourth terminal, and
a midpoint of the second inductor coil connects to the central terminal.
2. The device of claim 1 , wherein the first inductor coil is 180° rotationally symmetric about a symmetry point.
3. The device of claim 1 , wherein electromagnetic fields generated by currents circulating in the first inductor coil induce electromagnetic currents in the second inductor coil having magnitudes and directions such that the induced electromagnetic currents effectively cancel out.
4. The device of claim 1 , wherein the loop of the second inductor coil has a plurality of turns.
5. The device of claim 4 , wherein widths of the turns the loop of the second inductor coil vary moving from an innermost turn to an outermost turn.
6. The device of claim 4 , wherein the turns of the loop of the second inductor coil are separated by a spacing.
7. The device of claim 6 , wherein the spacing varies moving from an innermost turn to an outermost turn.
8. The device of claim 1 , wherein the first loop of the first inductor coil is octagonal, second loop of the first inductor coil is octagonal, and the loop of the second inductor coil is octagonal.
9. The device of claim 1 , wherein the first loop of the first inductor coil, the second loop of the first inductor coil, and the loop of the second inductor coil are fabricated using a same metal layer within an integrated circuit.
10. The device of claim 1 , wherein the first loop of the first inductor coil has a plurality of turns and the second loop of the first inductor coil has a plurality of turns.
11. The device of claim 10 , wherein widths of the turns of the first loop of the first inductor coil vary moving from an innermost turn to an outermost turn, and wherein widths of the turns the second loop of the first inductor coil vary moving from an innermost turn to an outermost turn.
12. The device of claim 10 , wherein the turns of the first loop of the first inductor coil are separated by spacings that vary moving from an innermost turn to an outermost turn, and wherein the turns of the second loop of the first inductor coil are separated by spacings that vary moving from an innermost turn to an outermost turn.
13. A oscillator circuit, comprising:
a five-terminal passive device comprising
a first inductor coil comprising a first loop connected to a first terminal and a central terminal and a second loop connected to a second terminal and the central terminal, wherein the first loop and the second loop are configured in a figure-of-eight so that a current flowing in the first inductor coil circulates around the first loop in a first rotational direction and circulates around the second loop in a second rotational direction opposite the first rotational direction, and
a second inductor coil comprising a loop that surrounds the first inductor coil, wherein a first end of the second inductor coil connects to a third terminal, a second end of the second inductor coil connects to a fourth terminal, and a midpoint of the second inductor coil connects to the central terminal;
a first voltage-controlled oscillator circuit coupled to the first terminal and the second terminal of the five-terminal passive device; and
a second voltage-controlled oscillator circuit coupled to the third terminal and the fourth terminal of the five-terminal passive device.
14. The oscillator circuit of claim 13 , wherein the central terminal is connected to an AC ground.
15. The oscillator circuit of claim 13 , wherein the first voltage-controlled oscillator circuit and second voltage-controlled oscillator circuit are operated concurrently without interaction.