Compact impedance transformer
View Patent ↗A compact impedance transformer is disclosed having a first dielectric substrate, a first planar conductor disposed on a top surface of the first dielectric substrate in a loop, a second planar conductor disposed on a bottom surface of the first dielectric substrate in a second loop, wherein the first planar conductor and the second planar conductor are substantially identical and in stacked alignment. A second dielectric substrate has a third planar conductor disposed on a top surface of the second dielectric substrate in a third loop, and a fourth planar conductor disposed on a bottom surface of the second dielectric substrate in a fourth loop, wherein the third planar conductor and the fourth planar conductor are substantially identical and in stacked alignment. An interconnect structure between terminals of the first planar conductor, the second planar conductor, the third planar conductor, and the fourth planar conductor provide impedance transformations.
1. A compact impedance transformer comprising:
a first dielectric substrate;
a first planar conductor disposed on a top surface of the first dielectric substrate in a first loop extending from a first-first terminal to a second-first terminal;
a second planar conductor disposed on a bottom surface of the first dielectric substrate in a second loop extending from a first-second terminal to a second-second terminal, wherein the first planar conductor and the second planar conductor are substantially identical and in stacked alignment with the first dielectric substrate residing there between;
a second dielectric substrate;
a third planar conductor disposed on a top surface of the second dielectric substrate in a third loop extending from a first-third terminal to a second-third terminal;
a fourth planar conductor disposed on a bottom surface of the second dielectric substrate in a fourth loop extending from a first-fourth terminal to a second-fourth terminal, wherein the third planar conductor and the fourth planar conductor are substantially identical and in stacked alignment with the second dielectric substrate residing there between; and
an interconnect structure that couples select ones of the first-first terminal, the second-first terminal, the first-second terminal, the second-second terminal, the first-third terminal, the second-third terminal, the first-fourth terminal, and the second-fourth terminal to provide impedance transformation between an input port comprised of the first-first terminal and the first-third terminal, and an output port comprised of the second-first terminal and the second-third terminal such that there is no common current return path between the first planar conductor, the second planar conductor, the third planar conductor and the fourth planar conductor.
2. The compact impedance transformer of claim 1 wherein electrical connections made by the interconnect structure are arranged between the first planar conductor, the second planar conductor, the third planar conductor, and the fourth planar conductor to provide an impedance transformation ratio of 4 to 1.
3. The compact impedance transformer of claim 1 wherein electrical connections made by the interconnect structure are arranged between the first planar conductor, the second planar conductor, the third planar conductor, and the fourth planar conductor to provide an impedance transformation ratio of 9 to 1.
4. The compact impedance transformer of claim 1 further comprising:
a third dielectric substrate;
a fifth planar conductor disposed on a top surface of the third dielectric substrate in a fifth loop extending from a first-fifth terminal to a second-fifth terminal; and
a sixth planar conductor disposed on a bottom surface of the third dielectric substrate in a sixth loop extending from a first-sixth terminal to a second-sixth terminal, wherein the fifth planar conductor and the sixth planar conductor are substantially identical and in stacked alignment with the third dielectric substrate residing there between.
5. The compact impedance transformer of claim 4 further including an interconnect structure that couples select ones of the first-first terminal, the second-first terminal, the first-second terminal, the second-second terminal, the first-third terminal, the second-third terminal, the first-fourth terminal, the second-fourth terminal, the first-fifth terminal, the second-fifth terminal, the first-sixth terminal, and the second-sixth terminal, to provide impedance transformation between an input port and an output port.
6. The compact impedance transformer of claim 5 wherein electrical connections made by the interconnect structure are arranged between the first planar conductor, the second planar conductor, the third planar conductor, the fourth planar conductor, the fifth planar conductor, and the sixth planar conductor to provide an impedance transformation ratio of 2.25 to 1.
7. The compact impedance transformer of claim 5 wherein electrical connections made by the interconnect structure are arranged between the first planar conductor, the second planar conductor, the third planar conductor, the fourth planar conductor, the fifth planar conductor, and the sixth planar conductor to provide an impedance transformation ratio of 6.25 to 1.
8. The compact impedance transformer of claim 4 further including a first discrete capacitor coupled between input terminals.
9. The compact impedance transformer of claim 8 wherein the first discrete capacitor has a capacitance value that ranges from around 0.4 pF to around 3.0 pF.
10. The compact impedance transformer of claim 4 further including a second discrete capacitor coupled between output terminals.
11. The compact impedance transformer of claim 10 wherein the second discrete capacitor has a capacitance value that ranges from around 0.5 pF to around 6.5 pF.
12. The compact impedance transformer of claim 1 wherein the first dielectric substrate is coplanar with the second dielectric substrate.
13. The compact impedance transformer of claim 1 wherein the first dielectric substrate and the second dielectric substrate are in stacked alignment and separated by a ground plane.
14. The compact impedance transformer of claim 4 wherein an insertion loss of the compact impedance transformer ranges from around 0.135 dB to around 0.549 dB.
15. The compact impedance transformer of claim 4 wherein a dimensions of the compact impedance transformer range in area from around 1750 μm by 1200 μm to around 5240 μm by 2400 μm.
16. The compact impedance transformer of claim 1 wherein a characteristic impedance for each of a first transmission line comprising the first planar conductor and the second planar conductor, and a second transmission line comprising the third planar conductor and the fourth planar conductor is around a geometric mean of an input impedance coupled between input terminals and an output impedance coupled between output terminals.
17. The compact impedance transformer of claim 1 wherein input terminals are adapted to couple to an impedance of around 50Ω, and output terminals are adapted to couple to an output impedance of around 5.6Ω.
18. The compact impedance transformer of claim 1 wherein input terminals are adapted to receive an RF signal having a center frequency that ranges from around 900 MHz to around 1800 MHz.
19. The compact impedance transformer of claim 1 wherein input terminals are adapted to receive an RF signal having a center frequency that ranges from around 1800 MHz to around 3600 MHz.