Abstract:
A system including a sensor circuit and comparison circuitry. The sensor circuit is configured to provide a sensed signal. The comparison circuitry is configured to receive an input signal that corresponds to the sensed signal. The comparison circuitry provides output signals that switch state at different levels of the input signal.

Description:
BACKGROUND 
     Sensors, referred to as contactless sensors, can be used to detect the position of a sensed object without contacting the sensed object. Contactless sensors include magnetic sensors, inductive sensors, and capacitive sensors. 
     Magnetic sensors include Hall-effect sensors and magneto-resistive (XMR) sensors. Where, magnetic sensors are used in sensors, such as position sensors, speed sensors, motion sensors, and proximity sensors in automotive, industrial and consumer applications. 
     Usually, in Hall-effect sensors, current flows through a Hall-effect sensing element or plate and a magnetic field perpendicular to the current flow deflects charge carriers due to the Lorentz force. The deflected charge carriers create a Hall voltage perpendicular to both the magnetic field and the current flow. This Hall voltage can be measured and is directly proportional to the magnetic field. 
     XMR sensors include anisotropic magneto-resistive (AMR) sensors, giant magneto-resistive (GMR) sensors, tunneling magneto-resistive (TMR) sensors, and colossal magneto-resistive (CMR) sensors. 
     Often, position sensors are two state switches, where the position sensor switches from one state to another state based on the distance that the sensed object is from the sensor. If the sensed object is closer to the sensor, the position sensor is in one state and if the sensed object is further away from the sensor, the position sensor is in another state. The position sensor, detects that the sensed object is in one of two regions. However, multiple position sensors are needed to detect that the sensed object is in one of more than two regions. This leads to an increase in the number of sensors and wiring, which increases system costs. 
     For these and other reasons there is a need for the present invention. 
     SUMMARY 
     One embodiment described in the disclosure provides a system including a sensor circuit and comparison circuitry. The sensor circuit is configured to provide a sensed signal. The comparison circuitry is configured to receive an input signal that corresponds to the sensed signal. The comparison circuitry provides output signals that switch state at different levels of the input signal. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide a further understanding of embodiments and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments and together with the description serve to explain principles of embodiments. Other embodiments and many of the intended advantages of embodiments will be readily appreciated as they become better understood by reference to the following detailed description. The elements of the drawings are not necessarily to scale relative to each other. Like reference numerals designate corresponding similar parts. 
         FIG. 1  is a diagram illustrating one embodiment of a sensor system that indicates the position of an object in one of four regions. 
         FIG. 2  is a diagram illustrating the operation of the sensor system of  FIG. 1 , where the sensor circuit is a Hall-effect magnetic field sensor. 
         FIG. 3  is a table illustrating the states of comparators and output signals versus regions. 
         FIG. 4  is a diagram illustrating one embodiment of a sensor system that indicates whether the strength of a magnetic field is in a middle region of three regions. 
         FIG. 5  is a diagram illustrating the operation of the sensor system of  FIG. 4 , where the sensor circuit is a Hall-effect magnetic field sensor. 
         FIG. 6  is a table illustrating the states of comparators and an output signal versus regions in the sensor system of  FIG. 4 . 
         FIG. 7  is a diagram illustrating one embodiment of a sensor system  300  that includes a multiplexer and multiple threshold voltages. 
     
    
    
     DETAILED DESCRIPTION 
     In the following Detailed Description, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. In this regard, directional terminology, such as “top,” “bottom,” “front,” “back,” “leading,” “trailing,” etc., is used with reference to the orientation of the Figure(s) being described. Because components of embodiments can be positioned in a number of different orientations, the directional terminology is used for purposes of illustration and is in no way limiting. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims. 
     It is to be understood that the features of the various exemplary embodiments described herein may be combined with each other, unless specifically noted otherwise. 
       FIG. 1  is a diagram illustrating one embodiment of a sensor system  20  that senses the position of an object (not shown) and indicates the position of the object in one of four regions. In one embodiment, sensor system  20  is a magnetic field position sensor. In one embodiment, sensor system  20  is a radio frequency (RF) position sensor. In one embodiment, sensor system  20  is part of a gear shift assembly. In other embodiments, sensor system  20  senses and indicates the position of an object in one region of n number of regions. 
     Sensor system  20  includes a sensor circuit  22 , an amplifier  24 , three comparators  26   a - 26   c , a logic circuit  28  and two output transistors  30   a  and  30   b . Sensor circuit  22  is electrically coupled to the inputs of amplifier  24  via sensed signal paths  32   a  and  32   b  and the output of amplifier  24  is electrically coupled to each of the comparators  26   a - 26   b  via input signal path  34 . 
     Sensor circuit  22  senses the object and provides sensed signals to amplifier  24  via sensed signal paths  32   a  and  32   b . Amplifier  24  receives the sensed signals at  32   a  and  32   b  and provides an amplified input signal to comparators  26   a - 26   c  via input path  34 , where the amplified input signal at  34  corresponds to the sensed signals at  32   a  and  32   b . In one embodiment, sensor circuit  22  is a magnetic sensor circuit. In one embodiment, sensor circuit  22  is an inductive sensor circuit. In one embodiment, sensor circuit  22  is a capacitive sensor circuit. In one embodiment, sensor circuit  22  is a Hall-effect sensor circuit. In one embodiment, sensor circuit  22  is a magneto-resistive (XMR) sensor circuit. 
     Each of the three comparators  26   a - 26   c  receives the input signal at  34  and compares the input signal at  34  to different threshold values. Also, each of the three comparators  26   a - 26   c  provides an output signal to logic circuit  28 . First comparator  26   a  is electrically coupled to logic circuit  28  via first output path  36   a , second comparator  26   b  is electrically coupled to logic circuit  28  via second output path  36   b , and third comparator  26   c  is electrically coupled to logic circuit  28  via third output path  36   c . In other embodiments, sensor system  20  includes n comparators that provide n output signals to logic circuit  28 . 
     First comparator  26   a  receives the input signal at  34  and compares the input signal at  34  to first threshold values. If the input signal at  34  is above the first threshold values, first comparator  26   a  provides a first output signal at  36   a  in one state, such as a low state. If the input signal at  34  is below the first threshold values, first comparator  26   a  provides the first output signal at  36   a  in another state, such as a high state. 
     Second comparator  26   b  receives the input signal at  34  and compares the input signal at  34  to second threshold values. If the input signal at  34  is above the second threshold values, second comparator  26   b  provides a second output signal at  36   b  in one state, such as a low state. If the input signal at  34  is below the second threshold values, second comparator  26   b  provides the second output signal at  36   b  in another state, such as a high state. 
     Third comparator  26   c  receives the input signal at  34  and compares the input signal at  34  to third threshold values. If the input signal at  34  is above the third threshold values, third comparator  26   c  provides a third output signal at  36   c  in one state, such as a low state. If the input signal at  34  is below the second threshold values, third comparator  26   c  provides the third output signal at  36   c  in another state, such as a high state. 
     Comparators, such as comparators  26   a - 26   c , are part of comparison circuitry  27 . In other embodiments, comparison circuitry  27  does not include comparators, such as comparators  26   a - 26   c , and comparisons of the input signal to the different threshold values are done via different comparison circuitry  27 , such as in a software solution where the input signal is sampled via an analog-to-digital (AD) converter (not shown) and comparisons are made via software calculations in a controller (not shown). 
     Logic circuit  28  receives the first, second, and third output signals at  36   a - 36   c  and provides logical output signals that indicate which one of the four regions the sensed object is in. Logic circuit  28  is electrically coupled to the input of first output transistor  30   a  via logic output path  38   a  and to the input of second output transistor  30   b  via logic output path  38   b . First output transistor  30   a  has a first output at  40   a  and is electrically coupled to a reference, such as ground, at  42 . Second output transistor  30   b  has a second output at  40   b  and is electrically coupled to a reference, such as ground, at  44 . In other embodiments, logic circuit  28  provides other signals that indicate which region the sensed object is in, signals such as pulse width modulated (PWM) signals, local interconnect network (LIN) signals, and/or controller area network (CAN) signals. 
     Logic circuit  28  receives the three output signals at  36   a - 36   c  and provides two logical output signals at  38   a  and  38   b  that indicate which one of four regions the object is in. The first logical output signal at  38   a  controls first output transistor  30   a  and the second logical output signal at  38   b  controls second output transistor  30   b  to output first and second output signals at  40   a  and  40   b , respectively. In other embodiments, logic circuit  28  receives n comparator output signals from n comparators and logic circuit  28  provides logical output signals to indicate which one of n+1 regions the object is in. 
     In operation, the sensed object is in one of four regions, where the first region is furthest away from sensor system  20 , the second region is closer to sensor system  20  than the first region but further away from sensor system  20  than the third region, the third region is closer to sensor system  20  than the second region but further away from sensor system  20  than the fourth region, and the fourth region is closest to sensor system  20 . 
     If the sensed object is in the first region, the input signal at  34  that corresponds to the sensed signals at  32   a  and  32   b , is below the first, second, and third threshold values and all three comparators  26   a - 26   c  output a high state. If the sensed object is in the second region, the input signal at  34  is above the first threshold values and below the second and third threshold values, such that first comparator  26   a  outputs a low state and second and third comparators  26   b  and  26   c  output high states. If the sensed object is in the third region, the input signal at  34  is above the first and second threshold values and below the third threshold values, such that first and second comparators  26   a  and  26   b  output low states and third comparator  26   c  outputs a high state. If the sensed object is in the fourth region, the input signal at  34  is above the first, second, and third threshold values and each of the three comparators  26   a - 26   c  outputs a low state. 
     Logic circuit  28  receives the comparator output signals at  36   a - 36   c  and outputs two logical output signals at  38   a  and  38   b , which control output transistors  30   a  and  30   b  to provide output signals at  40   a  and  40   b . If the sensed object is in the first region, all three comparators  26   a - 26   c  output a high state and logic circuit  28  controls output transistors  30   a  and  30   b  to output high states in the output signals at  40   a  and  40   b . If the sensed object is in the second region, such that first comparator  26   a  outputs a low state and second and third comparators  26   b  and  26   c  output high states. Logic circuit  28  receives the one low state and two high states and controls output transistor  30   a  to output a high state and output transistor  30   b  to output a low state. If the sensed object is in the third region, such that first and second comparators  26   a  and  26   b  output low states and third comparator  26   c  outputs a high state. Logic circuit  28  receives the two low states and the one high state and controls output transistor  30   a  to output a low state and output transistor  30   b  to output a high state. If the sensed object is in the fourth region, such that each of the comparators  26   a - 26   c  outputs a low state. Logic circuit  28  receives the three low states and controls output transistors  30   a  and  30   b  to output low states. 
     In other embodiments, sensor system  20  has n number of comparators, where each comparator has different threshold values. The input signal at  34  is compared via the n comparators to produce n comparator output signals. Logic circuit  28  receives the n comparator output signals and indicates which region of up to n+1 regions the sensed object is in. 
     Sensor system  20  senses the sensed object in one of more than two regions. Using sensor system  20  reduces the number of sensors and wiring, which reduces system costs. 
       FIG. 2  is a diagram illustrating the operation of sensor system  20 , where sensor circuit  22  is a Hall-effect magnetic field sensor. The high and low states at  100  of comparators  26   a - 26   c  are graphed versus the strength of the magnetic field B at  102 . As the sensed object gets closer to sensor system  20 , the magnetic field gets stronger. In region I at  104 , the magnetic field is weak and the object is furthest away from sensor system  20 . As the object moves closer to sensor system  20 , it passes through region II at  106 , region III at  108 , and into region IV at  110 . 
     In region I at  104 , the input signal at  34  that corresponds to the sensed signals at  32   a  and  32   b , is below the first, second, and third threshold values and each of the three comparators  26   a - 26   c  outputs a high state. As the object moves closer to sensor system  20 , comparator  26   a  switches from a high state to a low state at  112 , which is operating point one (BOP 1 ). In region II at  106 , the input signal at  34  is above the first threshold values and below the second and third threshold values, such that first comparator  26   a  outputs a low state and second and third comparators  26   b  and  26   c  output high states. As the object moves closer to sensor system  20 , comparator  26   b  switches from a high state to a low state at  114 , which is operating point two (BOP 2 ). In region III at  108 , the input signal at  34  is above the first and second threshold values and below the third threshold values, such that first and second comparators  26   a  and  26   b  output low states and third comparator  26   c  outputs a high state. As the object moves closer to sensor system  20 , comparator  26   c  switches from a high state to a low state at  116 , which is operating point three (BOP 3 ). In region IV at  110 , the input signal at  34  is above the first, second, and third threshold values and each of the three comparators  26   a - 26   c  outputs a low state. 
     As the sensed object moves further away from sensor system  20 , the magnetic field gets weaker. The object moves from region IV at  110 , to region III at  108 , to region II at  106 , to region I at  104 . Each of the three comparators  26   a - 26   c  is a hysteresis comparator that switches from a low state to a high state at a release point that is different than the operating point for that comparator. This stabilizes sensor system  20 , such that oscillations between regions due to electrical noise or mechanical vibrations are reduced. 
     In region IV at  110 , the input signal at  34  is above the first, second, and third threshold values and each of the three comparators  26   a - 26   c  outputs a low state. As the object moves further away from sensor system  20 , comparator  26   c  switches from a low state to a high state at  118 , which is release point three (BRP 3 ). In region III at  108 , the input signal at  34  is above the first and second threshold values and below the third threshold values, such that first and second comparators  26   a  and  26   b  output low states and third comparator  26   c  outputs a high state. As the object moves further away from sensor system  20 , comparator  26   b  switches from a low state to a high state at  120 , which is release point two (BRP 2 ). In region II at  106 , the input signal at  34  is above the first threshold values and below the second and third threshold values, such that first comparator  26   a  outputs a low state and second and third comparators  26   b  and  26   c  output high states. As the object moves further away from sensor system  20 , comparator  26   a  switches from a low state to a high state at  122 , which is release point one (BRP 1 ). In region I at  104 , the input signal at  34  that corresponds to the sensed signals at  32   a  and  32   b , is below the first, second, and third threshold values and each of the three comparators  26   a - 26   c  outputs a high state. 
       FIG. 3  is a table illustrating the states of comparators  26   a - 26   c  and output signals  40   a - 40   b  at  130  versus region at  132 . Comparator  26   a  is referred to as Comp 1  at  130   a , comparator  26   b  is referred to as Comp 2  at  130   b , and comparator  26   c  is referred to as Comp 3  at  130   c . Also, output signal  40   a  is referred to as Out 1  at  130   d  and output signal  40   b  is referred to as Out 2  at  130   e.    
     In region I at  132   a , each of the comparators  26   a - 26   c  outputs a high state and logic circuit  28  controls output transistors  30   a  and  30   b  to output high states in the output signals at  40   a  and  40   b . In region II at  132   b , first comparator  26   a  outputs a low state and second and third comparators  26   b  and  26   c  output high states, and logic circuit  28  controls output transistor  30   a  to output a high state and output transistor  30   b  to output a low state. In region III at  132   c , first and second comparators  26   a  and  26   b  output low states and third comparator  26   c  outputs a high state. Logic circuit  28  receives the two low states and the one high state and controls output transistor  30   a  to output a low state and output transistor  30   b  to output a high state. In region IV at  132   d , each of the comparators  26   a - 26   c  outputs a low state and logic circuit  28  controls output transistors  30   a  and  30   b  to output low states. 
       FIG. 4  is a diagram illustrating one embodiment of a sensor system  200  that senses whether the strength of a magnetic field, such as the magnetic field from an object, is in the middle region of three regions. In one embodiment, sensor system  200  is part of a position sensor that senses the position of the object. In one embodiment, sensor system  200  is part of a security system. In other embodiments, sensor system  200  senses and indicates whether the strength of the magnetic field is in one region of n regions. 
     Sensor system  200  includes a sensor circuit  202 , an amplifier  204 , two comparators  206   a  and  206   b , a logic circuit  208 , and an output transistor  210 . Sensor circuit  202  is electrically coupled to the inputs of amplifier  204  via sensed signal paths  212   a  and  212   b , and the output of amplifier  204  is electrically coupled to each of the comparators  206   a  and  206   b  via input signal path  214 . 
     Sensor circuit  202  senses the magnetic field and provides sensed signals to amplifier  204  via sensed signal paths  212   a  and  212   b . Amplifier  204  receives the sensed signals at  212   a  and  212   b  and provides an amplified input signal to comparators  206   a  and  206   b  via input path  214 , where the amplified input signal at  214  corresponds to the sensed signals at  212   a  and  212   b . In one embodiment, sensor circuit  202  is a magnetic sensor circuit. In one embodiment, sensor circuit  202  is an inductive sensor circuit. In one embodiment, sensor circuit  202  is a capacitive sensor circuit. In one embodiment, sensor circuit  202  is a Hall-effect sensor circuit. In one embodiment, sensor circuit  202  is an XMR sensor circuit. 
     Each of the comparators  206   a  and  206   b  receives the input signal at  214  and compares the input signal at  214  to different threshold values. Also, each of the comparators  206   a  and  206   b  provides an output signal to logic circuit  208 . First comparator  206   a  is electrically coupled to logic circuit  208  via first output path  216   a  and second comparator  206   b  is electrically coupled to logic circuit  208  via second output path  216   b . In other embodiments, sensor system  200  includes n comparators that provide n output signals to logic circuit  208 . 
     First comparator  206   a  receives the input signal at  214  and compares the input signal at  214  to first threshold values. If the input signal at  214  is above the first threshold values, first comparator  206   a  provides a first output signal at  216   a  in one state, such as a low state. If the input signal at  214  is below the first threshold values, first comparator  206   a  provides the first output signal at  216   a  in another state, such as a high state. 
     Second comparator  206   b  receives the input signal at  214  and compares the input signal at  214  to second threshold values. If the input signal at  214  is above the second threshold values, second comparator  206   b  provides a second output signal at  216   b  in one state, such as a low state. If the input signal at  214  is below the second threshold values, second comparator  206   b  provides the second output signal at  216   b  in another state, such as a high state. 
     Logic circuit  208  receives the first and second output signals at  216   a  and  216   b  and provides a logical output signal that indicates whether the strength of the magnetic filed is in the middle region of three regions. Logic circuit  208  is electrically coupled to the input of output transistor  210  via logic output path  218 . Output transistor  210  has an output at  220  and is electrically coupled to a reference, such as ground, at  222 . In other embodiments, logic circuit  208  provides other signals that indicate which region the sensed object is in, signals such as pulse width modulated (PWM) signals, local interconnect network (LIN) signals, and/or controller area network (CAN) signals. 
     Logic circuit  208  receives the output signals at  216   a  and  216   b  and provides a logical output signal at  218  that indicates whether the strength of the magnetic field is in the middle region of three regions. The logical output signal at  218  controls output transistor  210  to output an output signal at  220 . In other embodiments, logic circuit  208  receives n comparator output signals from n comparators and logic circuit  208  provides logical output signals to indicate which one of n+1 regions the strength of the magnetic field is in. 
     In operation, the sensed strength of the magnetic field is in one of three regions. The magnetic field strength is weakest in the first region, stronger in the second region than in the first region but weaker in the second region than in the third region, and strongest in the third region. 
     In the first region, the input signal at  214  that corresponds to the sensed signals at  212   a  and  212   b  is below the first and second threshold values and both comparators  206   a  and  206   b  output a high state. In the second region, the input signal at  214  is above the first threshold values and below the second threshold values, such that first comparator  206   a  outputs a low state and second comparator  206   b  outputs a high state. In the third region, the input signal at  214  is above the first and second threshold values, such that first and second comparators  206   a  and  206   b  output low states. 
     Logic circuit  208  receives the comparator output signals at  216   a  and  216   b  and outputs a logical output signal at  218 , which controls output transistor  210  to provide an output signal at  220 . In the first region, each of the comparators  206   a  and  206   b  outputs a high state and logic circuit  208  controls output transistors  210  to output a low state in the output signal at  220 . In the second region, first comparator  206   a  outputs a low state and second comparator  206   b  outputs a high state. Logic circuit  208  receives the low state and the high state and controls output transistor  210  to output a high state in the output signal at  220 . In the third region, first and second comparators  206   a  and  206   b  output low states and logic circuit  208  controls output transistor  210  to output a low state in the output signal at  220 . 
     In other embodiments, sensor system  200  has n number of comparators, where each comparator has different threshold values. The input signal at  214  is compared via the n comparators to produce n comparator output signals. Logic circuit  208  receives the n comparator output signals and indicates which region of up to n+1 regions the strength of the magnetic field is in. 
     Sensor system  200  indicates whether the strength of the magnetic field is in the second region via a high state in the output signal at  220 . If the strength of the magnetic field is lower and in the first region or higher and in the third region, sensor system  200  outputs a low state in the output signal at  220 . 
     In one embodiment, sensor system  200  is used in a security system, where sensor system  200  detects the position of an object, such as a door/window sensor magnet. If the strength of the magnetic field is in the second region, the door/window is closed and if the strength of the magnetic field is in the first region, the door/window is open. Also, if someone tries to over-ride the door/window sensor via an external magnet, the strength of the magnetic field may be pushed into the third region, where sensor system  200  outputs a low state in the output signal at  220 , which alerts the security system to a potential break-in at the door/window. 
       FIG. 5  is a diagram illustrating the operation of sensor system  200 , where sensor circuit  202  is a Hall-effect magnetic field sensor. The high and low states at  230  of comparators  206   a  and  206   b  are graphed versus the strength of the magnetic field B at  232 . In region I at  234 , the magnetic field is weakest. In region II at  236 , the magnetic field is stronger than in region I, but weaker than in region III at  238  where the magnetic field is strongest. 
     In region I at  234 , the input signal at  214  that corresponds to the sensed signals at  212   a  and  212   b , is below the first and second threshold values and each of the comparators  206   a  and  206   b  outputs a high state. As the magnetic field strength increases, such as by moving an object closer to sensor system  200 , comparator  206   a  switches from a high state to a low state at  240 , which is operating point one (BOP 1 ). In region II at  236 , the input signal at  214  is above the first threshold values and below the second threshold values, such that first comparator  206   a  outputs a low state and second comparator  206   b  outputs a high state. As the magnetic field strength increases, such as by moving an object closer to sensor system  200 , comparator  206   b  switches from a high state to a low state at  242 , which is operating point two (BOP 2 ). In region III at  238 , the input signal at  214  is above the first and second threshold values and each of the comparators  206   a  and  206   b  outputs a low state. 
     As the magnetic field decreases, such as by moving an object away from sensor system  200 , the strength of the magnetic field moves from region III at  238 , to region II at  236 , to region I at  234 . Each of the comparators  206   a  and  206   b  is a hysteresis comparator that switches from a low state to a high state at a release point that is different than the operating point for that comparator. This stabilizes sensor system  200 , such that oscillations between regions due to electrical noise or mechanical vibrations are reduced. 
     In region III at  238 , the input signal at  214  is above the first and second threshold values and each of the comparators  206   a  and  206   b  outputs a low state. As the magnetic field decreases, comparator  206   b  switches from a low state to a high state at  244 , which is release point two (BRP 2 ). In region II at  236 , the input signal at  214  is above the first threshold values and below the second threshold values, such that first comparator  206   a  outputs a low state and second comparator  206   b  outputs a high state. As the magnetic field decreases, comparator  206   a  switches from a low state to a high state at  246 , which is release point one (BRP 1 ). In region I at  234 , the input signal at  214  is below the first and second threshold values and each of the comparators  206   a  and  206   b  outputs a high state. 
       FIG. 6  is a table illustrating the states of comparators  206   a  and  206   b  and output signal  220  at  250  versus region at  252 . Comparator  206   a  is referred to as Comp 1  at  250   a , comparator  206   b  is referred to as Comp 2  at  250   b , and output signal  220  is referred to as Out at  250   c.    
     In region I at  252   a , each of the comparators  206   a  and  206   b  outputs a high state and logic circuit  208  controls output transistor  210  to output a low state in the output signal at  220 . In region II at  252   b , first comparator  206   a  outputs a low state and second comparator  206   b  outputs a high state, and logic circuit  208  controls output transistor  210  to output a high state. In region III at  252   c , first and second comparators  206   a  and  206   b  output low states and logic circuit  208  outputs a low state. 
     Sensor system  200  senses the strength of a magnetic field, such as a magnetic field from a sensed object and/or an external magnet, and indicates the strength of the magnetic field via more than two regions. Sensor system  200  provides a logical output signal via logic circuit  208  in sensor system  200 . Using sensor system  200  in a security system application can improve security. 
       FIG. 7  is a diagram illustrating one embodiment of a sensor system  300  that senses the position of an object (not shown) and indicates the position of the object in one of four regions. In one embodiment, sensor system  300  is a magnetic field position sensor. In one embodiment, sensor system  300  is a radio frequency (RF) position sensor. In one embodiment, sensor system  300  is part of a gear shift assembly. In other embodiments, sensor system  300  senses and indicates the position of an object in one region of n number of regions. 
     Sensor system  300  includes a sensor circuit  302 , an amplifier  304 , a comparator  306 , a logic circuit  308 , two output transistors  310   a  and  310   b , and a multiplexer  312 . Sensor circuit  302  is electrically coupled to the inputs of amplifier  304  via sensed signal paths  314   a  and  314   b  and the output of amplifier  304  is electrically coupled to comparator  306  via input signal path  316 . 
     Sensor circuit  302  senses the object and provides sensed signals to amplifier  304  via sensed signal paths  314   a  and  314   b . Amplifier  304  receives the sensed signals at  314   a  and  314   b  and provides an amplified input signal to comparator  306  via input path  316 , where the amplified input signal at  316  corresponds to the sensed signals at  314   a  and  314   b . In one embodiment, sensor circuit  302  is a magnetic sensor circuit. In one embodiment, sensor circuit  302  is an inductive sensor circuit. In one embodiment, sensor circuit  302  is a capacitive sensor circuit. In one embodiment, sensor circuit  302  is a Hall-effect sensor circuit. In one embodiment, sensor circuit  302  is a magneto-resistive (XMR) sensor circuit. 
     Multiplexer  312  receives three threshold voltages V 1 , V 2 , and V 3 . Multiplexer  312  receives threshold voltage V 1  at  318 , threshold voltage V 2  at  320 , and threshold voltage V 3  at  322 . Also, multiplexer  312  receives control signal CNTRL at  324  from control logic (not shown for clarity), such as a controller, a microprocessor, or another logic circuit. The output of multiplexer  312  is electrically coupled to a threshold voltage input of comparator  306  via threshold voltage path  326 . Control signal CNTRL at  324  controls multiplexer  312  to provide each of the three different threshold voltages V 1 , V 2 , and V 3  to comparator  306 . 
     Comparator  306  receives the input signal at  316  and compares the input signal at  316  to the threshold voltages V 1 , V 2 , and V 3  provided via multiplexer  312 . Comparator  306  is electrically coupled to logic circuit  308  via comparator output path  328  and comparator  306  provides an output signal to logic circuit  308  via comparator output path  328  for each comparison to one of the three threshold voltages V 1 , V 2 , and V 3 . Thus, if multiplexer  312  provides the three different threshold voltages V 1 , V 2 , and V 3  to comparator  306  over a given period of time, comparator  306  provides three output signals to logic circuit  308  over the same given period of time. In other embodiments, sensor system  300  includes n threshold voltages and comparator  306  compares the input signal at  316  to n threshold voltages and provides n corresponding output signals to logic circuit  308 . 
     Comparator  306  receives threshold voltage V 1  at  326  via multiplexer  312  and compares the input signal at  316  to the first threshold voltage V 1 . If the input signal at  316  is above the first threshold voltage V 1 , comparator  306  provides a first output signal at  328  in one state, such as a low state. If the input signal at  316  is below the first threshold voltage V 1 , comparator  306  provides the first output signal at  328  in another state, such as a high state. 
     Comparator  306  receives threshold voltage V 2  at  326  via multiplexer  312  and compares the input signal at  316  to the second threshold voltage V 2 . If the input signal at  316  is above the second threshold voltage V 2 , comparator  306  provides a second output signal at  328  in one state, such as a low state. If the input signal at  316  is below the second threshold voltage V 2 , comparator  306  provides the second output signal at  328  in another state, such as a high state. 
     Comparator  306  receives threshold voltage V 3  at  326  via multiplexer  312  and compares the input signal at  316  to the third threshold voltage V 3 . If the input signal at  316  is above the third threshold voltage V 3 , comparator  306  provides a third output signal at  328  in one state, such as a low state. If the input signal at  316  is below the third threshold voltage V 1 , comparator  306  provides the third output signal at  328  in another state, such as a high state. 
     Logic circuit  308  receives the first, second, and third output signals at  328  and control signal CNTRL at  324 . Logic circuit  308  provides logical output signals that indicate which one of the four regions the sensed object is in. Logic circuit  308  is electrically coupled to the input of first output transistor  310   a  via logic output path  330   a  and to the input of second output transistor  310   b  via logic output path  330   b . First output transistor  310   a  has a first output at  332   a  and is electrically coupled to a reference, such as ground, at  334 . Second output transistor  310   b  has a second output at  332   b  and is electrically coupled to a reference, such as ground, at  336 . In other embodiments, logic circuit  308  provides other signals that indicate which region the sensed object is in, signals such as pulse width modulated (PWM) signals, local interconnect network (LIN) signals, and/or controller area network (CAN) signals. 
     Logic circuit  308  receives the three output signals at  328  and provides two logical output signals at  330   a  and  330   b  that indicate which one of four regions the object is in. The first logical output signal at  330   a  controls first output transistor  310   a  and the second logical output signal at  330   b  controls second output transistor  310   b  to output first and second output signals at  332   a  and  332   b , respectively. In other embodiments, logic circuit  308  receives n comparator output signals and logic circuit  308  provides logical output signals to indicate which one of n+1 regions the object is in. 
     In operation, the sensed object is in one of four regions, where the first region is furthest away from sensor system  300 , the second region is closer to sensor system  300  than the first region but further away from sensor system  300  than the third region, the third region is closer to sensor system  300  than the second region but further away from sensor system  300  than the fourth region, and the fourth region is closest to sensor system  300 . 
     If the sensed object is in the first region, the input signal at  316  that corresponds to the sensed signals at  314   a  and  314   b  is below the first, second, and third threshold voltages V 1 , V 2 , and V 3  and comparator  306  outputs three high states. If the sensed object is in the second region, the input signal at  316  is above the first threshold voltage V 1  and below the second and third threshold voltages V 2  and V 3 , such that comparator  306  outputs a low state via the comparison to the first threshold voltage V 1  and high states via the comparisons to the second and third threshold voltages V 2  and V 3 . If the sensed object is in the third region, the input signal at  316  is above the first and second threshold voltages V 1  and V 2  and below the third threshold voltage V 3 , such that comparator  306  outputs low states via the comparisons to the first and second threshold voltages V 1  and V 2  and a high state via the comparison to the third threshold voltage V 3 . If the sensed object is in the fourth region, the input signal at  316  is above the first, second, and third threshold voltages V 1 , V 2 , and V 3  and comparator  306  outputs three low states. 
     Logic circuit  308  receives the comparator output signals at  328  and control signal CNTRL at  324  and outputs two logical output signals at  330   a  and  330   b , which control output transistors  310   a  and  310   b  to provide output signals at  332   a  and  332   b . If the sensed object is in the first region, logic circuit  308  controls output transistors  310   a  and  310   b  to output high states in the output signals at  332   a  and  332   b . If the sensed object is in the second region, logic circuit  308  receives the one low state and two high states and controls output transistor  310   a  to output a high state and output transistor  310   b  to output a low state. If the sensed object is in the third region, logic circuit  308  receives the two low states and the one high state and controls output transistor  310   a  to output a low state and output transistor  310   b  to output a high state. If the sensed object is in the fourth region, logic circuit  28  receives the three low states and controls output transistors  30   a  and  30   b  to output low states. 
     In other embodiments, sensor system  300  has n number of different threshold voltages. The input signal at  316  is compared via the n threshold voltages to produce n comparator output signals. Logic circuit  308  receives the n comparator output signals and indicates which region of up to n+1 regions the sensed object is in. 
     Sensor system  300  senses the sensed object in one of more than two regions. Using sensor system  300  reduces the number of sensors and wiring, which reduces system costs. 
     Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations may be substituted for the specific embodiments shown and described without departing from the scope of the present invention. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Therefore, it is intended that this invention be limited only by the claims and the equivalents thereof.