High speed DLL offset cancellation
AssigneeAnalog Devices, Inc.
InventorRalph Moore
Life of this patent
Estimating the term…
Abstract
In an embodiment, a primary charge pump and replica charge pump may be coupled to matching control mechanisms and loads. In an embodiment, the replica charge pump may produce an error current originating from charge pump timing mismatches in a steady locked loop state. The error current produced by the replica charge pump may be measured by a difference amplifier to adjust at least one current source to compensate for the error current originating from the timing mismatches. To adjust the current sources, the amplifier may cause the current source to produce an equal but opposite current to cancel the effects of the error current, resulting in a constant output voltage.
Claims20
A device comprising:
- a first current source coupled to a second current source, a single first switch, a first filter, and an input of an amplifier, the single first switch is a sole switch controlling a current flow path between the first current source, the second current source, the first filter, and the input of the amplifier;
- and
- a third current source coupled to a fourth current source, a second filter, and a single second switch, the single second switch is a sole switch controlling a current flow path between the third current source, the fourth current source, and the second filter;
- wherein an output of the amplifier controls current in the first and third current sources.
A method comprising:
- inputting an output of a first and second current source to an amplifier, the second current source activated by a single first switch that is a sole switch controlling a current flow path between the first current source, the second current source, a first filter, and an input of the amplifier;
- varying a current in the first current source and a third current source based on an output of the amplifier, the third current source coupled to a fourth current source activated by a single second switch that is a sole switch controlling a current flow path between the third current source, the fourth current source, and a second filter;
- and
- activating the single first and second switches to equalize a first voltage at the first filter between the first and second current sources and a second voltage at the second filter between the third and fourth current sources.
A device comprising:
- a first current source coupled to a second current source, a first switch, a first filter, and an input of an amplifier, the first switch is a sole switch controlling a current flow path between the first current source, the second current source, the first filter, and the input of the amplifier;
- a third current source coupled to a fourth current source, a second filter, and a second switch, the second switch is a sole switch controlling a current flow path between the third current source, the fourth current source, and the second filter;
- wherein an output of the amplifier controls current in the second and fourth current sources.
A method comprising:
- inputting an output of a first and second current source to an amplifier, the second current source activated by a first switch that is a sole switch controlling a current flow path between the first current source, the second current source, a first filter, and an input of the amplifier;
- varying a current in the first current source and a third current source based on an output of the amplifier, the third current source coupled to a fourth current source, the fourth current source activated by a second switch that is a sole switch controlling a current flow path between the third current source, the fourth current source, and a second filter;
- and
- activating the first and the second switches to equalize a first voltage at the first filter between the first and second current sources and a second voltage at the second filter between the third and fourth current sources.
Dependencies are inferred from the claim text.