1. A thermal switch comprising:
a shunt in contact with a heat source, said shunt including a post thermally coupled to said heat source;
a cup thermally coupled to a heat sink, wherein the cup includes an annular portion at least partially surrounding a portion of the post, leaving a gap therebetween; and
an axial isolator coupled to the cup and the post, for maintaining the radial gap between the post and the annular portion of the cup;
wherein the cup and the post have different coefficients of linear thermal expansion, such that the post and the annular portion selectively thermally couple together depending on temperatures of the annular portion and the post.
2. The thermal switch of claim 1,
wherein the post is a first post, wherein the cup is a first cup; and
wherein the shunt further includes a second cup with a second annular portion at least partially surrounding a portion of a second post.
3. The thermal switch of claim 2,
wherein the cups are thermally coupled to respective heat sinks; and
wherein the thermal switch allows disengagement of one of the cups when the heat sink coupled to the other of the cups is in operation.
4. The thermal switch of claim 1, wherein the shunt is an integral part of the device to be cooled.
5. The thermal switch of claim 1, wherein the cup includes aluminum.
6. The thermal switch of claim 1, wherein the post includes beryllium.
7. The thermal switch of claim 1, wherein the post has a circular cross-section.
8. The thermal switch of claim 1, wherein the annular portion fully radially surrounds the portion of the post.
9. A thermal switch comprising:
a post thermally coupled to a heat source;
a cup thermally coupled to a heat sink, wherein the cup includes an annular portion at least partially surrounding a portion of the post, leaving a gap therebetween;
an axial isolator coupled to the cup and the post, for maintaining the radial gap between the post and the annular portion of the cup; and
a polymer disk between the cup and an end of the posts;
wherein the cup and the post have different coefficients of linear thermal expansion, such that the post and the annular portion selectively thermally couple together depending on temperatures of the annular portion and the post.
10. The thermal switch of claim 9, wherein the disk have cutouts such that its shape is other than circular.
11. A thermal switch comprising:
a post thermally coupled to a heat source;
a cup thermally coupled to a heat sink, wherein the cup includes an annular portion at least partially surrounding a portion of the post, leaving a gap therebetween; and
an axial isolator coupled to the cup and the post, for maintaining the radial gap between the post and the annular portion of the cup;
wherein the cup and the post have different coefficients of linear thermal expansion, such that the post and the annular portion selectively thermally couple together depending on temperatures of the annular portion and the post; and
wherein the gap between the cup and the post conforms to the equations:
g
a
=
\u222b
T
1
T
0
\u2062
(
\u03b1
o
\u2061
(
T
)
–
\u03b1
i
\u2061
(
T
)
)
\u2062
R
\u2062
\u2146
T
g
b
=
pR
E
i
\u2062
(
R
2
+
R
i
2
R
2
–
R
i
2
–
v
i
)
+
pR
E
o
\u2062
(
R
o
2
+
R
2
R
o
2
–
R
2
–
v
o
)
g
=
g
a
–
g
b
wherein R2 is an inside radius of the cup, R1 an outside radius of the post, g is the gap between the cup and the post (g=R2\u2212R1), p is a desired operating pressure, Ro is a maximum allowable cup outside radius, gn is a radial thermal contraction term, gb is a radial interference term, T1 is an operating temperature, T0 is an ambient temperature, \u03b1ois the coefficient of linear thermal expansion (CTE) for the cup, \u03b1i is the CTE for the post, R is a transition radius which can be approximated by R1, Ei is an elastic modulus of the post, Eo is an elastic modulus of the cup, Ri is an inside radius of the post, \u03bdi is Poisson’s ratio of the post, and \u03bdo is Poisson’s ratio of the cup.
12. A thermal switch comprising:
a shunt thermally coupled to a heat source, wherein the shunt includes having a pair of posts thermally coupled to one another;
a pair of cups thermally coupled to respective heat sinks, wherein the cups include respective annular portions at least partially surrounding portions of the posts, leaving respective gaps therebetween; and
a pair of an axial isolators coupling the cups to the respective posts, for maintaining the radial gaps between the posts and the annular portions of the cups;
wherein the annular portions have a lower coefficient of thermal expansion than the shunt, such that the posts and the annular portion selectively thermally couple together depending on temperatures of the annular portions and the posts.
13. The thermal switch of claim 12, wherein the shunt is an integral pert of the device to be cooled.
14. The thermal switch of claim 12, wherein the pair of posts are part of a single piece of material.
15. The thermal switch of claim 14, wherein the single piece of material includes beryllium.
16. The thermal switch of claim 15, wherein annular portions of the cups include aluminum.
17. The thermal switch of claim 12,
wherein the cups include respective isolators; and
wherein the isolators are inserted into recesses in the posts, in order to maintain the gaps between the posts and the annular portions.
18. The thermal switch of claim 17, wherein the isolators include respective titanium protruding portions.
19. The thermal switch of claim 12, further comprising disks of material between the cups and ends of the posts.
20. The thermal switch of claim 19, wherein the disks include a polymer material.
21. The thermal switch of claim 19, wherein the disks have cutouts such that their shape is other than circular.
22. The thermal switch of claim 12, wherein the annular portions fully radially surround the portions of the posts.
23. A method of selectively coupling a heat source to one of a pair of heat sinks, the method comprising:
thermally coupling the heat source to a shunt;
radially contracting a first cup at least partially around a first post of a shunt, thereby causing contact between the first cup and the post, and establishing a low thermal impedance path between one of the heat sinks and the heat source and the shunt; and
maintaining isolation between a second post of the shunt from a second cup by means of an axial isolator wherein the second cup is thermally coupled to the other of the heat sinks.
24. A method of selectively coupling a heat source to one of a pair of heat sinks, the method comprising:
placing first and second cups, coupled to respective of the heat sinks, at least partially around respective first and second posts, wherein the posts are parts of a shunt that is an integral part of the heat source;
radially contracting the first cup, thereby causing contact between the first cup and the post, and establishing a low thermal impedance path between one of the heat sinks and the heat source; and
maintaining isolation between the second post and the second cup by use of an axial isolator at least partially between the second post and the second cup.
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. An apparatus comprising:
a first stage configured to receive an input signal and provide an output signal; and
a load stage coupled to the first stage and configured to provide an active load for the first stage, the load stage and the first stage being independently linearized by canceling distortion generated by the active load.
2. The apparatus of claim 1, wherein the load stage comprises
a first transistor configured to provide the active load for the first stage, the first transistor generating distortion due to nonlinearity, and
at least one transistor coupled to the first transistor and configured to generate a replica of the distortion from the first transistor, the distortion replica being used to cancel the distortion from the first transistor.
3. The apparatus of claim 2, wherein the at least one transistor comprises a second transistor configured to receive an output of the first transistor and generate the distortion replica based on the output of the first transistor.
4. The apparatus of claim 2, wherein the at least one transistor is coupled in parallel with the first transistor and configured to receive at least one bias voltage.
5. The apparatus of claim 2, wherein the at least one transistor has bias selected to match the distortion replica to the distortion from the first transistor.
6. The apparatus of claim 2, wherein the at least one transistor has size selected to match the distortion replica to the distortion from the first transistor.
7. The apparatus of claim 2, wherein the first transistor and the at least one transistor comprise field effect transistors (FETs).
8. The apparatus of claim 1, wherein the load stage is linearized by canceling third-order intermodulation (IM3) distortion generated by the active load.
9. The apparatus of claim 1, wherein the load stage comprises a transistor configured to provide the active load for the first stage, and wherein the apparatus further comprises:
an operational amplifier coupled to the transistor and configured to set bias of the transistor.
10. The apparatus of claim 9, wherein the operational amplifier is configured to provide a gate voltage for the transistor to set a drain voltage of the transistor at a bias voltage.
11. The apparatus of claim 1, wherein the first stage is configured to amplify the input signal and provide the output signal having a larger signal level.
12. The apparatus of claim 1, wherein the first stage comprises
a first transistor configured to receive and amplify the input signal, the first transistor generating distortion due to nonlinearity, and
a second transistor coupled to the first transistor and configured to generate a replica of the distortion from the first transistor, the distortion replica being used to cancel the distortion from the first transistor.
13. The apparatus of claim 12, wherein the second transistor is configured to receive the input signal and generate the distortion replica based on the input signal.
14. The apparatus of claim 12, wherein the second transistor is configured to receive an output of the first transistor and generate the distortion replica based on the output of the first transistor.
15. The apparatus of claim 12, wherein the first stage further comprises
a third transistor coupled to the first transistor and configured to receive an output of the first transistor and provide the output signal, the third transistor providing load isolation for the first transistor.
16. The apparatus of claim 1, wherein the first stage is configured to receive a differential input signal and provide a differential output signal, and wherein the load stage is configured to provide a differential active load for the first stage.
17. An integrated circuit comprising:
a first stage configured to receive an input signal and provide an output signal; and
a load stage coupled to the first stage and configured to provide an active load for the first stage, the load stage and the first stage being independently linearized by canceling distortion generated by the active load.
18. The integrated circuit of claim 17, wherein the load stage comprises
a first transistor configured to provide the active load for the first stage, the first transistor generating distortion due to nonlinearity, and
at least one transistor coupled to the first transistor and configured to generate a replica of the distortion from the first transistor, the distortion replica being used to cancel the distortion from the first transistor.
19. The integrated circuit of claim 17, wherein the first stage is configured to amplify the input signal and provide the output signal having a larger signal level.
20. The integrated circuit of claim 17, wherein the first stage is configured to mix the input signal with a local oscillator (LO) signal at a first frequency and provide the output signal at a second frequency.
21. An apparatus comprising:
means for processing an input signal with an active load to obtain an output signal; and
means for canceling distortion generated by the active load at a first stage and a load stage to reduce distortion in the output signal, wherein the first stage and the load stage are independently linearized.
22. The apparatus of claim 21, wherein the means for canceling the distortion generated by the active load comprises
means for generating a replica of the distortion generated by the active load, and
means for canceling the distortion generated by the active load with the distortion replica.
23. The apparatus of claim 21, wherein the means for processing the input signal comprises means for amplifying the input signal to obtain the output signal having a larger signal level.
24. A method comprising:
processing an input signal with an active load to obtain an output signal; and
canceling distortion generated by the active load at a first stage and a load stage to reduce distortion in the output signal, wherein the first stage and the load stage are independently linearized.
25. The method of claim 24, wherein the canceling the distortion generated by the active load comprises
generating a replica of the distortion generated by the active load, and
canceling the distortion generated by the active load with the distortion replica.
26. The method of claim 24, wherein the processing the input signal comprises amplifying the input signal to obtain the output signal having a larger signal level.
27. A wireless communication device comprising:
an antenna operative to provide an input signal; and
a low noise amplifier (LNA) operatively coupled to the antenna and comprising a first stage and a load stage, the first stage configured to receive the input signal and provide an output signal, the load stage being coupled to the first stage, configured to provide an active load for the first stage, and the load stage and the first stage being independently linearized by canceling distortion generated by the active load.