1. A synchronization circuit, comprising:
a pulse width modulated (PWM) input signal;
an inverter having an input coupled to the pulse width modulated input signal;
a first resistor tree coupled to an output of the inverter;
an instrumentation amplifier having an input coupled to the first resistor tree,
wherein the instrumentation amplifier is configured to measure a level of ripple in the PWM input signal;
a filter coupled to an output of the instrumentation amplifier,
wherein the filter is configured to detect a change in the measured level of the ripple, and
wherein a motor stall is determined when the change in the measured level of the ripple exceeds a predetermined threshold; and
an analog to digital converter coupled to an output of the filter.
2. The circuit of claim 1, further comprising a second resistor tree coupled to the output of the inverter and to the instrumentation amplifier.
3. The circuit of claim 2, further comprising a load coupled between the first resistor tree and the second resistor tree.
4. The circuit of claim 3, further comprising a buffer coupled between the pulse width modulated input signal and the first resistor tree and second resistor tree.
5. The circuit of claim 1 wherein the filter is configurable to track changes in a ripple level in the pulse width modulated input signal.
6. The circuit of claim 5 wherein the filter comprises a low pass filter.
7. A synchronization circuit, comprising:
a pulse width modulated (PWM) input signal;
a load coupled in series with the pulse width modulated input signal;
an instrumentation amplifier having a first input coupled to the load,
wherein the instrumentation amplifier is configured to measure a level of ripple in the PWM input signal;
a resistor coupled between the first input and a second input of the instrumentation amplifier;
a switch coupled to the second input of the instrumentation amplifier,
wherein the switch is configured to select between a first voltage and a second voltage;
a filter coupled to an output of the instrumentation amplifier,
wherein the filter is configured to detect a change in the measured level of the ripple, and
wherein a motor stall is determined when the change in the measured level of the ripple exceeds a predetermined threshold; and
an analog to digital converter coupled to an output of the filter.
8. The circuit of claim 7 wherein the filter is configurable to track changes in a ripple level in the pulse width modulated input signal.
9. The circuit of claim 7 wherein the filter comprises a low pass filter.
10. A method of performing synchronization, comprising:
sampling an analog signal and forming a digital data stream representing the analog signal;
filtering the digital data stream to remove harmonics;
measuring an approximate level of ripple in the digital data stream;
detecting a change in the measured level of ripple; and
based upon the change in the measured level of ripple, determining if a motor stall has occurred.
11. The method of claim 10, further comprising the step of filtering the digital data stream with a high pass filter to remove DC offset.
12. The method of claim 10, wherein the step of filtering the digital data stream to remove harmonics comprises applying a notch filter to the digital data stream.
13. The method of claim 10 wherein the step of measuring an approximate level of ripple comprises passing the digital data stream to a level detector.
14. The method of claim 10 wherein the step of detecting a change in the measured level of ripple comprises comparing the measured ripple level with a baseline ripple level.
15. The method of claim 10 wherein the step of determining if a stall has occurred comprises comparing the change in the measured level of ripple with a threshold value and if the threshold value is exceeded, signaling that a stall has occurred.
16. A synchronization circuit for a motor, comprising:
means for sampling an analog signal and forming a digital data stream representing the analog signal;
means for filtering the digital data stream;
means for measuring a level of ripple in the digital data stream;
means for detecting a change in the measured level of ripple in the digital data stream; and
means for determining if the motor has stalled based upon the change detected in the measured level of ripple.
17. The circuit of claim 16 wherein the means for filtering the digital data stream comprises a notch filter to remove harmonics.
18. The circuit of claim 17 wherein the means for filtering the digital data stream further comprises a high pass filter to remove a DC offset in the digital data stream.
19. The circuit of claim 16 wherein the means for detecting a change in the measured level of ripple in the digital data stream comprises a level detector through which the digital data stream is passed.
20. The circuit of claim 19 wherein the means for detecting a change in the measured level of ripple further comprises a low pass filter having an input coupled to an output of the level detector to track changes in the level of ripple caused by rotation speed changes of the motor.
21. The circuit of claim 20 wherein the means for detecting a change in the measured level of ripple further comprises a comparator having a first input coupled to an output of the low pass filter and a second input coupled to the output of the level detector to compare the ripple level out of the level detector with a filtered baseline level out of the low pass filter.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A device comprising:
an electrode;
an alloy electrode; and
an active region sandwiched between the electrode and the alloy electrode, the alloy electrode forms dopants in a sub-region of the active region adjacent to the alloy electrode such that the dopant can be selectively positioned within the active region to control the flow of charge carriers between the electrode and the alloy electrode, the active region comprising:
a primary active layer comprising a material for transporting the dopant that controls the flow of charge carriers through the device; and
a secondary active layer comprising the sub-region and providing one of a source and a sink of the dopants for the primary active region, wherein the secondary active layer comprises the material of the primary active layer that has reacted with the alloy electrode.
2. The device of claim 1 wherein the alloy electrode causes the secondary active layer to form adjacent to the alloy electrode and the primary active layer to form within the active region adjacent to the electrode.
3. The device of claim 1 wherein the dopant further comprises one of: an oxygen vacancy, a nitrogen vacancy, a sulfur vacancy, a carbon vacancy, an anion vacancy, aliovalent element, a p-type impurity, and an n-type impurity.
4. The device of claim 1 wherein the primary active layer further comprises a material that is electronically semiconducting, nominally electronically insulating, or weakly ionic conducting.
5. The device of claim 1 wherein the primary active layer further comprises a film having an electrical conductivity that is capable of being reversibly changed from a relatively low conductivity to a relatively high conductivity as a function of the dopants drifting into or out of the at least one primary active region.
6. The device of claim 1 wherein the material for the primary active layer and the material for the secondary active layer are selected from the group consisting of titanates, zirconates, hafnates, lanthanates, manganites, other suitable alloys of these oxides in pairs or with oxides present together, and compounds of the type A.sup.++B.sup.4+O.sub.3.sup.\u2212\u2212, where A represents at least one divalent element and B represents at least one of titanium, zirconium, and hafnium.
7. The device of claim 1 wherein the material for the primary active layer and secondary active region can be a semiconducting nitride, a semiconducting halide, an elemental semiconductor, or a compound semiconductor.
8. The device of claim 1 the material for the primary active layer and secondary active layer can be a nitride, sulfide, phosphide or a carbide.
9. The device of claim 1 wherein positioning the dopant further comprises positioning the dopant near an electrodeactive region interface making the interface Ohmic-like and positioning the dopant away from an electrodeactive region interface making the interface Schottky-like.
10. The device of claim 1 wherein the electrode further comprises a second alloy electrode such that the second alloy electrode forms dopants in a second sub-region of the active region adjacent to the second alloy electrode.
11. The device of claim 1 wherein the alloy electrode further comprises a metal or semiconductor and at least one material that forms vacancies in the active region or a semiconductor dopant that diffuses into the active region.
12. A nanowire crossbar comprising:
a first layer of substantially parallel nanowires;
a second layer of substantially parallel nanowires overlaying the first layer of nanowires; and
at least one nanowire intersection forming an electronic device configured in accordance with claim 1.
13. The crossbar of claim 12 wherein the first layer of nanowires further comprise a metal or a semiconductor and the second layer of nanowires further comprise an alloy.
14. The crossbar of claim 13 wherein any two overlapping nanowires in the first and second layers form an electronic device configured in accordance with claim 1.
15. A nanowire crossbar comprising:
a first layer of substantially parallel nanowires;
a second layer of substantially parallel nanowires overlaying the first layer of nanowires; and
a nanowire intersection forming an electronic device comprising:
an electrode;
an alloy electrode; and
an active region sandwiched between the electrode and the alloy electrode, the active region comprising:
a primary active layer comprising a material for transporting dopants that controls the flow of charge carriers through the device; and
a secondary active layer configured to provide one of a source and a sink of the dopants for the primary active region, wherein the secondary active layer comprises the material of the primary active layer that has reacted with the alloy electrode;
wherein a voltage applied to the electrode and the alloy electrode induces a controllable flow of charge carries via the dopants between electrode and the alloy electrode.
16. The device of claim 15, wherein the primary active layer further comprises a film having an electrical conductivity configured to be reversibly changed from a relatively low conductivity to a relatively high conductivity as a function of the dopants drifting into or out of the primary active layer of the active region.
17. The device of claim 15, wherein the electrode further comprises a second alloy electrode, wherein the active region comprises a tertiary active layer configured to provide one of a source and a sink of the dopants for the primary active region, wherein the third active layer comprises the material of the primary active layer that has reacted with the second alloy electrode.
18. The crossbar of claim 15, wherein the first layer of nanowires further comprises a metal or a semiconductor and the second layer of nanowires further comprises an alloy.