Sensor having a shaped coil
Methods and apparatus for sensing target position by generating a signal by energizing a shaped coil with an AC signal. A sensor receives a signal reflected by a target in response to the signal from the shaped coil, wherein the shaped coil has a first width, and wherein the sensor includes a first sensing element aligned with the shaped coil at the first width, wherein a ratio of the first width and a distance from the sensor to the target is about three-to-one. The received signal can be processed to determine position information of the target. In some embodiments, a shaped coil can have a trapezoidal shape and sensors aligned with the coil to select a sensor based upon target to sensor distance.
1. A method, comprising:
generating a signal by energizing a shaped coil with an AC signal;
receiving at a sensor a signal reflected by a target in response to the signal from the shaped coil, wherein the shaped coil has a varying width, and wherein the sensor includes a first sensing element aligned with the shaped coil at a first width and a second sensing element aligned with shaped coil at a second width; and
selecting a first one of the first and second sensing elements based upon a ratio of coil width and a distance from the target to the shaped coil,
wherein a peak of a slope of the received signal in G/m corresponds to a width of the selected first one of the first and second sensing elements.
2. The method according to claim 1 , wherein the ratio of the selected coil width and a distance from the sensor to the target is about three-to-one.
3. The method according to claim 2 , wherein the ratio is three-to-one plus/minus ten percent.
4. The method according to claim 1 , wherein the shaped coil has a trapezoidal shape.
5. The method according to claim 1 , wherein the width of the coil changes linearly.
6. The method according to claim 1 , wherein the shaped coil and the sensor form part of a sensor IC package.
7. A magnetic sensor IC package, comprising:
a coil to generate a signal by energizing the shaped coil with an AC signal; and
a sensor to receive a signal reflected by a target in response to the signal from the shaped coil, wherein the shaped coil has a varying width, and wherein the sensor includes a first sensing element aligned with the shaped coil at a first width and a second sensing element aligned with shaped coil at a second width, wherein a first one of the first and second sensing elements is selectable based upon a ratio of coil width and a distance from the target to the shaped coil.
8. The magnetic sensor IC package according to claim 7 , wherein the ratio of the selected coil width and a distance from the sensor to the target is about three-to-one.
9. The magnetic sensor IC package according to claim 8 , wherein the ratio is three-to-one plus/minus ten percent.
10. The magnetic sensor IC package according to claim 7 , wherein a peak of a slope of the received signal in G/m corresponds to a width of the selected first one of the first and second sensing elements.
11. The magnetic sensor IC package according to claim 7 , wherein the shaped coil has a trapezoidal shape.
12. The magnetic sensor IC package according to claim 7 , wherein the width of the coil changes linearly.
13. A magnetic sensor IC package, comprising:
a coil means for generating a signal by energizing the coil means with an AC signal; and
a sensor means for receiving a signal reflected by a target in response to the signal from the coil means, wherein the coil means has a coil varying width, and wherein the sensor means includes a first sensing element aligned with the coil at a first width and a second sensing element aligned with coil at a second width, wherein a first one of the first and second sensing elements is selectable based upon a ratio of coil width and a distance from the target to the coil.