1. A lead free solder consisting essentially of 1.5 wt % to about 2.5 wt % silver (Ag), about 3 wt % to about 6 wt % bismuth (Bi), about 0.005 wt % to about 0.1 wt % of a deoxidizing agent, and a balance of tin (Sn).
2. The lead free solder of claim 1, wherein the deoxidizing agent is at least one metal selected from the group consisting of aluminum (Al), silicon (Si), manganese (Mn), titanium (Ti) and lithium (Li).
3. The lead free solder of claim 2, wherein the deoxidizing agent is aluminum (Al).
4. The lead free solder of claim 1, wherein the deoxidizing agent is contained in an amount from about 0.005 wt % to about 0.05 wt %.
5. The lead free solder of claim 1, wherein bismuth (Bi) is contained in an amount from about 4.5 wt % to about 6 wt %.
6. The lead free solder of claim 1, wherein silver (Ag) is contained in an amount from 1.7 wt % to 2.3 wt %.
7. The lead free solder of claim 1, wherein the silver (Ag) is included in an amount of 1.7 wt % to 2.3 wt %, the bismuth (Bi) is included in an amount of about 4.5 wt % to about 6 wt % and the deoxidizing agent is included in an amount of about 0.005 wt % to about 0.05 wt %.
8. The lead free solder of claim 7, wherein the deoxidizing agent is at least one metal selected from the group consisting of aluminum (Al), silicon (Si), manganese (Mn), titanium (Ti) and lithium (Li).
9. The lead free solder of claim 8, wherein the deoxidizing agent is aluminum (Al).
10. The lead free solder of claim 1, wherein a melting point of the lead free solder ranges from about 230\xb0 C. to about 210\xb0 C.
11. The lead free solder of claim 10, wherein a melting point of the lead free solder ranges from about 204\xb0 C. to about 207\xb0 C.
12. A lead free solder consisting essentially of 1.5 wt % to 2.5 wt % silver (Ag), about 3 wt % to about 6 wt % bismuth (Bi), about 0.005 wt % to about 0.1 wt % of aluminum (Al), and a balance of tin (Sn).
13. The lead free solder of claim 12, wherein aluminum (Al) is contained in an amount from about 0.005 wt % to about 0.05 wt %.
14. The lead free solder of claim 12, wherein Bismuth (Bi) is contained in an amount from about 4.5 wt % to about 6 wt %.
15. The lead free solder of claim 12, wherein silver (Ag) is contained in an amount from 1.7 wt % to about 2.3 wt %.
16. The lead free solder of claim 12, wherein the silver (Ag) is included in an amount of 1.7 wt % to 2.3 wt %, the bismuth (Bi) is included in an amount of about 4.5 wt % to about 6 wt %, and the aluminum (Al) is included in an amount of about 0.005 wt % to about 0.05 wt %.
17. The lead free solder of claim 12, wherein a melting point of the lead free solder ranges from about 203\xb0 C. to about 210\xb0 C.
18. The lead free solder of claim 17, wherein a melting point of the lead free solder ranges from about 204\xb0 C. to about 207\xb0 C.
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 for amplifying a radio frequency (RF) signal, the apparatus comprising:
a ring structure configured to distribute one or more input signals such that the one or more input signals are divided into equal parts going around the ring structure clockwise and counterclockwise;
two or more RF amplifiers having inputs coupled to an interior of the ring structure; and
a power combining circuit located interior to the ring structure, the power combining circuit coupled to outputs of the two or more RF amplifiers, the power combining circuit configured to combine the outputs of the two or more RF amplifiers.
2. The apparatus of claim 1, wherein the ring structure further comprises one or more input ports configured to couple the one or more input signals to the ring structure from outside the circumference of the ring structure.
3. The apparatus of claim 1, wherein the ring structure is implemented with microstrip.
4. The apparatus of claim 1, wherein each of the two or more RF amplifiers is physically located within an interior of the circumference of the ring structure.
5. The apparatus of claim 1, further comprising a phase shifter in a signal path between the ring structure and an RF amplifier of the two or more RF amplifiers.
6. The apparatus of claim 1, further comprising an isolator in a signal path between an RF amplifier of the two or more RF amplifiers and the power combining circuit.
7. The apparatus of claim 1, wherein the power combining circuit comprises a Wilkinson power combiner.
8. The apparatus of claim 1, wherein the power combining circuit is configured to generate an output approximately in a center of the ring structure.
9. The apparatus of claim 1, the ring structure having a circumference of an integer multiple of full wavelengths of the one or more input signals.
10. The apparatus of claim 1, wherein an arc length between ports is an integer multiple of full wavelengths.
11. The apparatus of claim 1, wherein an arc length between ports of the ring structure is an integer multiple of half wavelengths, further comprising at least one phase shifter in a signal path between the ring structure and the power combining circuit to align signals to be combined.
12. The apparatus of claim 1, wherein an arc length between ports of the ring structure is an integer multiple of quarter wavelengths, further comprising at least one phase shifter in a signal path between the ring structure and the power combining circuit to align signals to be combined.
13. The apparatus of claim 1, wherein an arc length between ports of the ring structure is an integer multiple of quarter wavelengths, further comprising phase shifters in signal paths between the ring structure and the power combining circuit for \xbe wavelength, \xbd wavelength, and \xbc wavelength for phase alignment.