Multi-phase Closed Loop LC Tank Circuits
LC tank circuits can be coupled together to form closed loop oscillators. The interconnectivity of these LC tank circuits were performed by a physical connection such as a metal interconnect. The LC tank circuits may also comprise a plurality of inductors that are coupled together in parallel. These closed loop oscillators generate oscillations which have multi-phase components. Such circuits are useful for RF designs, clock generation for VLSI chips, adiabatic circuitry, analog circuitry, and high-speed digital circuitry.
1 . A closed loop oscillator, comprising:
a first terminal and a second terminal;
a plurality of oscillators; wherein,
each oscillator comprises:
a first input node and a second input node;
a first output node and a second output node; and,
and LC tank circuit coupled to the first and second output nodes; wherein
the LC tank circuit is comprised of a plurality of inductors connected in parallel;
the first terminal is coupled to the first input node of a first oscillator;
the second terminal is coupled to the second input node of the first oscillator; and,
the plurality of oscillators are coupled in series; wherein
the first output node of a previous oscillator is coupled to one of the input nodes of a next oscillator;
the second output node of the previous oscillator is coupled to the remaining input node of the next oscillator;
the first output node of a last oscillator is coupled to either of the first or second terminals; and,
the second output node of the last oscillator is coupled to the remaining terminal.
2 . The oscillator of claim 1 , wherein:
the LC tank circuit further comprises at least one capacitor.
3 . The oscillator of claim 1 , wherein:
each oscillator further comprises:
a regenerative circuit coupled to the first and second output nodes.
4 . The oscillator of claim 1 , wherein:
each oscillator further comprises:
a first component coupling the first output node to a power supply node controlled by the first input node; and,
a second component coupling the second output node to the power supply node controlled by the second input node.
5 . The oscillator of claim 4 , wherein:
the first and second components are MOS transistors.
6 . The oscillator of claim 1 , further comprising:
at least one balanced pair of output signals.
7 . The oscillator of claim 6 , wherein:
the balanced pair of output signals each drive a capacitor load.
8 . The oscillator of claim 1 , wherein:
the first and second outputs of each oscillator provides the balanced pair of output signals.
9 . The oscillator of claim 8 , wherein:
the collection of the balanced pair of output signals generates a multi-phase clock signal.
10 . The oscillator of claim 1 , wherein:
the plurality of oscillators consist of an odd number of oscillators.
11 . The oscillator of claim 10 , wherein:
the first and second output nodes of each oscillator cross each other an even number of times while forming the closed loop of the oscillator.
12 . The oscillator of claim 1 , wherein:
the plurality of oscillators consist of an even number of oscillators.
13 . The oscillator of claim 12 , wherein:
the first and second output nodes of each oscillator cross each other an odd number of times while forming the closed loop of the oscillator.
14 . A method of forming a closed loop oscillator, comprising the steps of:
selecting a plurality of oscillators where each oscillator comprises:
a first input node and a second input node;
a first output node and second output node; and
an LC tank circuit coupled to the first and second output nodes; wherein,
the LC tank circuit is comprised of a plurality of inductors connected in parallel;
connecting the plurality of oscillators in series to form the closed loop; wherein,
the first output node of a previous oscillator is coupled to one of the input nodes of a next oscillator; and,
the second output node of the previous oscillator is coupled to the remaining input node of the next oscillator;
coupling the first output node of a last oscillator to either of the first or second input nodes of a first oscillator; and,
coupling the second output node of the last oscillator to the remaining input node of the first oscillator; thereby,
forming the closed loop oscillator.
15 . The method of claim 13 , wherein:
each oscillator further comprises:
a cross-coupled regenerative circuit coupled to the first and second output nodes.
16 . The method of claim 13 , wherein:
each oscillator further comprises:
a first component controlled by the first input node that couples a power supply node to the first output node; and,
a second component controlled by the second input node that couples the power supply mode to the second output node.
17 . The method of claim 13 , wherein:
the first and second output nodes of each oscillator can drive a capacitor load.
18 . The method of claim 13 , wherein:
the first and second output nodes of each oscillator provides a balanced clock signal.
19 . The method of claim 18 , wherein:
the collection of the balanced signals generates a multi-phase clock signal.
20 . A closed loop oscillator, comprising:
a plurality of oscillators; wherein,
each oscillator comprises:
a first input node and a second input node;
a first output node and a second output node;
a first component coupled between a power supply node and the first output node; wherein
the first component is controlled by the first input node;
a second component coupled between the power supply node and the second output node; wherein,
the second component is controlled by the second input node;
an LC tank circuit coupled to the first and second output nodes; and,
a regenerative circuit coupled to the first and second output nodes; and,
the plurality of oscillators coupled in series to form a closed loop; wherein,
the first output node of a previous oscillator is coupled to one of the input nodes of a next oscillator;
the second output node of the previous oscillator is coupled to the remaining input node of the next oscillator;
the first output node of a last oscillator is coupled to one of the input nodes of a first oscillator; and,
the second output node of the last oscillator is coupled to the remaining input node of the first oscillator.
21 . The oscillator of claim 20 , wherein:
the LC tank circuit further comprises at least one capacitor.
22 . The oscillator of claim 20 , wherein:
an inductance of the LC tank circuit is comprised of a plurality of inductors connected in parallel.
23 . The oscillator of claim 20 , wherein:
each oscillator further comprises:
a regenerative circuit coupled to the first and second output nodes.
24 . The oscillator of claim 20 , wherein:
the first and second components are MOS transistors.
25 . The oscillator of claim 20 , further comprising:
at least one balanced pair of output signals.
26 . The oscillator of claim 25 , wherein:
the balanced pair of output signals each drive a capacitor load.
27 . The oscillator of claim 20 , wherein:
the first and second outputs of each oscillator provides the balanced pair of output signals.
28 . The oscillator of claim 27 , wherein:
the collection of the balanced pair of output signals generates a multi-phase clock signal.
29 . The oscillator of claim 20 , wherein:
the plurality of oscillators consist of an odd number of oscillators.
30 . The oscillator of claim 29 , wherein:
the first and second output nodes of each oscillator cross each other an even number of times while forming the closed loop of the oscillator.
31 . The oscillator of claim 20 , wherein:
the plurality of oscillators consist of an even number of oscillators.
32 . The oscillator of claim 31 , wherein:
the first and second output nodes of each oscillator cross each other an odd number of times while forming the closed loop of the oscillator.