1. A method for treating a surface of a substrate, comprising:
forming reactive sites on the surface of the substrate by exposing the surface of the substrate to a first atmospheric plasma formed from a first process gas comprising an inert gas; and
functionalizing the reactive sites by exposing the surface of the substrate to a second atmospheric plasma formed from a second process gas comprising the inert gas and water vapor (H2O).
2. The method of claim 1, wherein forming the reactive sites further comprises:
removing impurities on the surface of the substrate using the first atmospheric plasma to expose the reactive sites on the surface.
3. The method of claim 1, wherein forming the reactive sites further comprises:
forming radicals on the surface of the substrate by breaking chemical bonds using the first atmospheric plasma, wherein in at least a first portion of the radicals are the reactive sites.
4. The method of claim 3, wherein forming the reactive sites further comprises:
forming protected sites by crosslinking at least a second portion of the radicals.
5. The method of claim 4, where forming the reactive sites further comprises:
controlling a ratio of reactive sites to protected sites on the surface of the substrate by adjusting one or more of flow rate of the first process gas, temperature of the substrate, density of the first atmospheric plasma, power of the first atmospheric plasma, distance between the substrate and one or more electrodes used to form the first atmospheric plasma or duration of exposure to the first atmospheric plasma.
6. The method of claim 1, wherein functionalizing the reactive sites further comprises:
removing impurities on the surface of the substrate using the second atmospheric plasma.
7. The method of claim 1, wherein functionalizing the reactive sites further comprises:
controlling a type of functional group formed at the reactive sites formed by adjusting one or more of the ratio of the inert gas to water vapor in the second process gas, the temperature of the substrate, the density of the second atmospheric plasma, power of the second atmospheric plasma, distance between the substrate and one or more electrodes used to form the second atmospheric plasma, or a duration of exposure to the second atmospheric plasma.
8. The method of claim 7, wherein the type of functional groups formed at the reactive sites includes at least one of hydroxyl groups, ketone groups, carbonyl or carboxylic acid groups.
9. The method of claim 1, further comprising:
forming a layer on the surface of the substrate by exposing the surface of the substrate to a layer forming species.
10. The method of claim 9, wherein the layer forming species is included with the second process gas and wherein exposing the surface of the substrate to the second atmospheric plasma further comprises:
exposing the surface of the substrate to a second atmospheric plasma formed from a second process gas comprising the inert gas, water vapor (H2O) and a layer forming species to functionalize the reactive sites formed by exposure to the first atmospheric plasma and to react the functionalized reactive sites with the layer forming species to form the layer on the surface of the substrate.
11. The method of claim 9, wherein forming the layer on the surface of the substrate further comprises:
exposing the surface of the substrate to the layer forming species after exposure to the second atmospheric plasma.
12. The method of claim 9, wherein forming the layer on the surface of the substrate further comprises:
reacting the functionalized reactive sites with the layer forming species to form a bond between the functionalized reactive sites and the layer forming species.
13. The method of claim 12, wherein the layer forming species may include one or more of isocyanate, urethane, vinyl ester and epoxy-based adhesives, alkylsilanes, or perfluoroalkylsilanes.
14. The method of claim 9, wherein forming the layer on the surface of the substrate further comprises:
depositing the layer on the surface of the substrate from the layer forming species using one or more of chemical vapor deposition, physical vapor deposition, sputtering, spray deposition, casting, spin coating, or dip coating.
15. The method of claim 1, wherein the substrate comprises at least one of a polymer, a ceramic, a composite material, a hybrid material or a metal.
16. The method of claim 1, wherein the inert gas comprises at least one of helium (He), argon (Ar), neon (Ne) xenon (Xe), krypton (Kr), radon (Rn), nitrogen (N2), hydrogen (H2), or air.
17. A method for treating a surface of a substrate, comprising:
forming radicals on the surface of the substrate by exposing the surface to a first atmospheric plasma formed from a first process gas comprising an inert gas to break chemical bonds on the surface, wherein a first portion of the radicals form reactive sites on the surface and a second portion of the radicals form protective sites on the surface;
functionalizing the reactive sites formed by the first atmospheric plasma by exposing the surface of the substrate to a second atmospheric plasma formed from a second process gas comprising the inert gas and water vapor (H2O); and
forming a layer on the functionalized surface of the substrate by exposing the surface of the substrate to a layer forming species during or after exposure to the second atmospheric plasma.
18. The method of claim 17, wherein exposing the surface to the first and second atmospheric plasmas further comprises
removing impurities on the surface of the substrate using the first and second atmospheric plasmas.
19. The method of claim 17, wherein forming the layer on the functionalized surface of the substrate further comprises:
depositing the layer on the functionalized surface of the substrate using one or more of chemical vapor deposition, physical vapor deposition, sputtering, spray deposition, casting, spin coating, or dip coating.
20. A method for treating a surface of a polymer substrate, comprising:
exposing a surface of polymer substrate to a first atmospheric plasma in an open atmosphere, wherein the open atmosphere comprises a first process gas comprising an inert gas to form reactive sites on the surface of the substrate and the open atmosphere temperature and first plasma process temperature range from about 20\xb0 C. to about 30\xb0 C. and the open atmosphere pressure and first plasma process pressure range from about 700 Torr to about 800 Torr;
exposing the surface of the substrate to a second atmospheric plasma formed from a second process gas comprising the inert gas and water vapor (H2O) at a water vapor mass fraction of at least about 50 mg\xb7g\u22121 of gas mixture to functionalize the reactive sites wherein the open atmosphere temperature and second plasma process temperature range from about 20\xb0 C. to about 30\xb0 C., the open atmosphere pressure and second plasma process pressure range from about 700 Torr to about 800 Torr and the open atmosphere humidity and second plasma process humidity are at least about 50 percent relative humidity; and
forming a layer on the functionalized surface of the substrate by exposing the surface of the substrate to a layer forming species during or after exposure to the second atmospheric plasma
wherein the treatment increases the oxygen content of the polymer substrate surface, increases the hydrophilicity of the polymer substrate surface by at least 10 percent and increases the adhesive strength of the film as measured by T-Peel testing according to ASTM 1876-01.
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 saturation detection and warning circuit to detect the impending saturation of an amplifier, the amplifier having a supply voltage, having inverting and non-inverting input terminals, the amplifier including at least one output transistor providing an output current and an output voltage on an output terminal, having an amplifier front end circuitry connected to the input terminals and controlling the output current of the output transistor,
the saturation detection and warning circuit comprising:
a threshold voltage that tracks changes in process, temperature, supply voltage and output current thereby maximizing the usable output signal range of the amplifier.
2. The saturation detection and warning circuit of claim 1 comprising:
a current mirror transistor having a current that matches the output current of the output transistor with a substantially fixed ratio,
a replica transistor having a current that tracks the output current of the output transistor, the replica transistor having a drain-source voltage that generates the threshold voltage; and
biasing circuitry that biases the replica transistor to set the drain source voltage of the replica transistor to the desired threshold voltage.
3. The saturation detection and warning circuit of claim 2 where the current mirror transistor and replica transistor are implemented with a single transistor.
4. The saturation detection and warning circuit of claim 2 further comprising:
a comparator to compare a Vds drain source voltage of the output transistor and the threshold voltage and to generate a warning signal if the Vds falls below the threshold voltage.
5. The circuit of claim 4, wherein the comparator includes controlled hysteresis.
6. The saturation detection and warning circuit of claim 2 where the threshold voltage is a substantially fixed fraction of a Vdssat voltage of the output transistor, where Vdssat is a drain source voltage of the output transistor at a border of its saturated operating region.
7. The saturation detection and warning circuit of claim 2 where the threshold voltage is a substantially fixed multiple of a minimum drain source voltage of the output transistor, Vdsmin, that can be attained with a given supply voltage and the amplifier front end circuit driving the supply voltage on a control terminal of the output transistor to its maximum absolute value.
8. The circuit of claim 1, further comprising:
a clamp circuit to clamp the output voltage of the amplifier at a controlled level between the threshold voltage and a maximum output voltage the amplifier can provide, that tracks the threshold voltage with an offset.
9. The circuit of claim 8, wherein the offset is substantially fixed.
10. The circuit of claim 8 including a transconductance amplifier with a nonlinear gain having
an inverting and a non-inverting input terminals, one connected to the threshold voltage the other connected to the output terminal of the amplifier,
a controlled offset voltage,
a clamp output terminal generating a clamp current that is dependent of the voltage difference between its two input terminals,
the clamp output terminal being connected to an inverting input terminal of the amplifier.
11. The circuit of claim 10, further comprising:
a comparator to compare a Vds drain source voltage of the output transistor and the threshold voltage and to generate a warning signal if the Vds falls below the threshold voltage, where the clamp circuit and the comparator circuit share significant circuitry to minimize die size and cost.
12. A drop out detection and warning circuit to detect the impending drop-out of a low drop-out linear voltage regulator (LDO) the LDO comprising an input voltage and an output voltage and output current, an error amplifier having two input terminals, one monitoring the output voltage, the other connected to a reference voltage, a pass transistor controlled by the error amplifier,
the drop out detection and warning circuit comparing a drain source voltage of the pass transistor with a threshold voltage that tracks changes in process, temperature, supply voltage and output current, the drop-out detection and warning circuit having an output
terminal that signals that the LDO is close to or about to drop out.
13. The drop out detection and warning circuit of claim 12, comprising:
a current mirror transistor having a current that matches a current of the pass transistor with a substantially fixed ratio;
a replica transistor having a current that tracks the current of the pass transistor, the replica transistor having a drain-source voltage that generates the threshold voltage, and
circuitry that biases the replica transistor to set the drain source voltage of the replica transistor to a desired threshold voltage.
14. The saturation detection and warning circuit of claim 13 where the current mirror transistor and replica transistor are implemented with a single transistor.
15. The drop out detection and warning circuit of claim 13 further comprising:
a comparator to compare a Vds drain source voltage of the pass transistor and the threshold voltage, the comparator to generate a warning signal if the Vds falls below the threshold voltage.
16. The circuit of claim 15, wherein the comparator includes a controlled hysteresis.
17. The drop out detection and warning circuit of claim 13 where the threshold voltage is a substantially fixed fraction of a Vdssat voltage of the pass transistor, the Vdssat voltage being the drain source voltage of the output transistor at the border of its saturated operating region.
18. The drop out detection and warning circuit of claim 13 where the threshold voltage is a substantially fixed multiple of a minimum drain source voltage of the pass transistor, Vdsmin, that can be attained with a given input voltage and an error amplifier driving a voltage on a control terminal of the output transistor to its maximum absolute value.