1. A pseudo resistor circuit comprising:
a first field effect transistor;
a second field effect transistor having electrical characteristics matched with electrical characteristics of the first field effect transistor;
a voltage dividing circuit including a reference resistor with a first terminal electrically connected to a source terminal of the second field effect transistor;
a first operational amplifier including:
an inverting input terminal, a non-inverting input terminal, and
an output terminal electrically connected to respective gate terminals of the first and second field effect transistors,
wherein one of the inverting and non-inverting input terminals is electrically connected to a node between a second terminal of the reference resistor and the source terminal of the second field effect transistor, and
wherein the other of the inverting and non-inverting input terminals of the first operational amplifier is coupled to a reference voltage; and
a second operational amplifier including an input terminal electrically connected to respective drain terminals of the first and second field effect transistors and an output terminal electrically coupled to a second terminal of the reference resistor.
2. The pseudo resistor circuit according to claim 1, wherein the second operational amplifier is configured to supply to the reference resistor a voltage resulting from inversion and amplification of drain voltage of the drain terminal of the first field effect transistor electrically connected to the drain terminal of the second field effect transistor.
3. The pseudo resistor circuit according to claim 1, further comprising an absolute value circuit configured to supply an absolute value voltage of the drain voltage of the first field effect transistor to the input terminal of the second operational amplifier and the drain terminal of the second field effect transistor.
4. The pseudo resistor circuit according to claim 1, further comprising a first voltage source coupled between the gate terminal of the second field effect transistor and the gate terminal of the first field effect transistor.
5. The pseudo resistor circuit according to claim 4, wherein the first voltage source is a direct-current voltage with a negative terminal of electrically connected to the gate terminal of the first field effect transistor and a positive terminal electrically connected to the gate terminal of the second field effect transistor.
6. The pseudo resistor circuit according to claim 4, wherein the first voltage source is a floating voltage source including a proportional to absolute temperature current source and a resistor.
7. The pseudo resistor circuit according to claim 4, further comprising a second voltage source coupled between the gate terminal of the first field effect transistor and the gate terminal of the second field effect transistor.
8. The pseudo resistor circuit according to claim 7, wherein the second voltage source is a floating voltage source including a proportional to absolute temperature current source and a resistor.
9. The pseudo resistor circuit according to claim 1, further comprising a first voltage source coupled between the drain terminal of the second field effect transistor and the drain terminal of the first field effect transistor.
10. The pseudo resistor circuit according to claim 9, wherein the first voltage source is a direct-current voltage with a negative terminal of electrically connected to the drain terminal of the first field effect transistor and a positive terminal electrically connected to the drain terminal of the second field effect transistor.
11. The pseudo resistor circuit according to claim 9, wherein the first voltage source is a floating voltage source including a proportional to absolute temperature current source and a resistor.
12. The pseudo resistor circuit according to claim 1, wherein the non-inverting input terminal of the first operational amplifier is coupled to the reference voltage and the inverting input terminal of the first operational amplifier is coupled to node between the second terminal of the reference resistor and the source terminal of the second field effect transistor.
13. The pseudo resistor circuit according to claim 1, wherein the inverting input terminal of the first operational amplifier is coupled to the reference voltage and the non-inverting input terminal of the first operational amplifier is coupled to node between the second terminal of the reference resistor and the source terminal of the second field effect transistor.
14. A charge amplifier comprising:
a pseudo resistor circuit including:
a first field effect transistor;
a second field effect transistor having electrical characteristics matched with electrical characteristics of the first field effect transistor;
a voltage dividing circuit including a reference resistor with a first terminal electrically connected to a source terminal of the second field effect transistor;
a first operational amplifier including: an inverting input terminal, a non-inverting input terminal, and
an output terminal electrically connected to respective gate terminals of the first and second field effect transistors,
wherein one of the inverting and non-inverting input terminals is electrically connected to a node between a second terminal of the reference resistor and the source terminal of the second field effect transistor, and
wherein the other of the inverting and non-inverting input terminals of the first operational amplifier is coupled to a reference voltage; and
a second operational amplifier including an input terminal electrically connected to respective drain terminals of the first and second field effect transistors and an output terminal electrically coupled to a second terminal of the reference resistor; and
a third operational amplifier including an inverting input terminal electrically connected to a source terminal of the first field effect transistor, a non-inverting input terminal electrically coupled to the reference voltage, and an output terminal electrically connected to the drain terminal of the first field effect transistor.
15. The charge amplifier according to claim 14, further comprising a capacitor electrically connected between the inverting input terminal of the third operational amplifier and the output terminal of the third operational amplifier and between the source terminal of the first field effect transistor and the drain terminal of the first field effect transistor.
16. The charge amplifier according to claim 14, wherein the second operational amplifier is configured to supply to the reference resistor a voltage resulting from inversion and amplification of drain voltage of the drain terminal of the first field effect transistor electrically connected to the drain terminal of the second field effect transistor.
17. The charge amplifier according to claim 14, wherein the pseudo resistor circuit further comprises an absolute value circuit configured to supply an absolute value voltage of the drain voltage of the first field effect transistor to the input terminal of the second operational amplifier and the drain terminal of the second field effect transistor.
18. The charge amplifier according to claim 14, wherein the pseudo resistor circuit further comprises a first voltage source coupled between the gate terminal of the second field effect transistor and the gate terminal of the first field effect transistor.
19. The charge amplifier according to claim 18, wherein the first voltage source is a floating voltage source including a proportional to absolute temperature current source and a resistor.
20. The charge amplifier according to claim 19, wherein the pseudo resistor circuit further comprises a second voltage source coupled between the gate terminal of the first field effect transistor and the gate terminal of the second field effect transistor.
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 method of capturing motion using motion capture cameras, comprising:
coupling a plurality of markers to an actor;
positioning a material between the actor and said motion capture cameras but in front of the plurality of markers toward the motion capture cameras, wherein said material is selected as a mesh material that is substantially transparent to said motion capture cameras when the markers are illuminated with a light source such that the plurality of markers is visible to the motion capture cameras, and the mesh material is visible to the actor so that the actor interacts with said material and physical movements of the actor appear natural for a person interacting with such a material; and
capturing the motion of said markers.
2. The method of claim 1, wherein said material is selected to be substantially invisible to said motion capture cameras.
3. The method of claim 1, wherein said material includes a fabric.
4. The method of claim 3, wherein said fabric includes tulle.
5. The method of claim 3, wherein said fabric is configured as a garment, said garment including a theatrical costume.
6. A method of capturing motion using motion capture cameras, comprising:
coupling a plurality of markers to an actor;
positioning a material between the actor and said motion capture cameras but in front of the plurality of markers toward the motion capture cameras, wherein said material is selected to be substantially transparent to said motion capture cameras when the markers are illuminated with a light .source such that the plurality of markers is visible to the motion capture cameras, and the material is visible to the actor so that the actor interacts with said material and physical movements of the actor appear natural for a person interacting with such a material; and
capturing the motion of said markers,
wherein said material includes a mesh.
7. The method of claim 6, wherein said mesh is flexible.
8. The method of claim 6, wherein said mesh includes a metal screen and a metal wire frame.
9. A method of capturing motion using motion capture cameras, comprising:
coupling a plurality of markers to an actor;
positioning a material between the actor and said motion capture cameras but in front of the plurality of markers toward the motion capture cameras, wherein said material is selected as a mesh material that is substantially transparent to said motion capture cameras when the markers are illuminated with a light source such that the plurality of markers is visible to the motion capture cameras, and the mesh material is visible to the actor so that the actor interacts with said material and physical movements of the actor appear natural for a person interacting with such a material; and
capturing the motion of said markers,
wherein said material is configured as a theatrical prop, the prop being separate from any clothing the actor is wearing.
10. A system for capturing motion using motion capture cameras, comprising:
a plurality of markers coupled to an actor;
a plurality of motion capture cameras configured to capture motion of said plurality of markers; and
a material positioned between the actor and said plurality of motion capture cameras but in front of the plurality of markers toward the motion capture cameras, wherein said material is selected as a mesh material that is substantially transparent to said motion capture cameras when the markers are illuminated with a light source such that the plurality of markers is visible to the plurality of motion capture cameras, and the mesh material is visible to the actor so that the actor interacts with said material and physical movements of the actor appear natural for a person interacting with such a material.
11. The motion capture system of claim 10, wherein said material includes a fabric.
12. The motion capture system of claim 11, wherein said fabric includes tulle.
13. The motion capture system of claim 11, wherein said fabric is configured as a garment, said garment including a theatrical costume.
14. The motion capture system of claim 10, further comprising a motion capture processing module configured to determine a location and a movement of at least one of said plurality of motion capture markers.
15. A system for capturing motion using motion capture cameras, comprising:
a plurality of markers coupled to an actor;
a plurality of motion capture cameras configured to capture motion of said plurality of markers; and
a material positioned between the actor and said plurality of motion capture cameras but in front of the plurality of markers toward the motion capture cameras, wherein said material is selected to be substantially transparent to said motion capture cameras when the markers are illuminated with a light source such that the plurality of markers is visible to the motion capture cameras, and said material is visible to the actor so that the actor interacts with said material and physical movements of the actor appear natural for a person interacting with such a material,
wherein said material includes a mesh.
16. The motion capture system of claim 15, wherein said mesh is flexible.
17. The motion capture system of claim 15, wherein said mesh includes a metal screen and a metal wire frame.
18. A system for capturing motion using motion capture cameras, comprising:
a plurality of markers coupled to an actor;
a plurality of motion capture cameras configured to capture motion of said plurality of markers; and
a material positioned between the actor and said plurality of motion capture cameras but in front of the plurality of markers toward the motion capture cameras, wherein said material is selected as a mesh material that is substantially transparent to said motion capture cameras when the markers are illuminated with a light source such that the plurality of markers is visible to the o capture cameras, and the mesh material is visible to the actor so that the actor interacts with said material and physical movements of the actor appear natural for a person interacting with such a material,
wherein said material is configured as a theatrical prop, the prop being separate from any clothing the actor is wearing.
19. An apparatus for capturing motion using motion capture cameras, comprising:
means for coupling a plurality of markers to an actor;
a mesh material positioned between the actor and said motion capture cameras but in front of the plurality of markers toward the motion capture cameras, wherein said mesh material is selected to be substantially transparent to said motion capture cameras when the markers are illuminated with a light source such that the plurality of markers are visible to the motion capture cameras, and the mesh material is visible to the actor so that the actor interacts with said material and physical movements of the actor appear natural for a person interacting with such a material; and
means for capturing the motion of said markers.