Method for designing coupling-function based millimeter wave electrical elements
A miniaturized (compact) millimeter wave hybrid based on a coupling function and associated method for designing millimeter wave electrical elements based on a coupling function is provided. The invention overcomes a drawback of conventional coupled transmission lines structures and equivalent lumped elements in that they are considerably large in size for IC designs making such structures unsuitable for use in RFICs' designs. Hence, such structures are not partial in millimeter wave electrical elements, and more particularly elements that should be integrated in devices for 60 GHz applications.
1. A miniaturized millimeter wave hybrid, comprising: a first metal line that connects a first port to a third port, wherein the first metal line is wound, a first number of turns, on a first metal layer of a multilayer substrate; a second metal line that connects a second port to a fourth port, wherein the second metal line is wound in a close proximity to the first metal line, a second number of turns, on a first metal layer and, in part, on a second metal layer of a multilayer substrate, thereby resulting in a spiraled structure; wherein the first port receives an input radio-frequency (RF) signal and each of the third port and the fourth port outputs an output RF signal having a phase difference relatively to the input RF signal, wherein the resulting structure is characterized by an uneven and unlocalized distribution of mutual inductance and capacitance.
2. The miniaturized millimeter wave hybrid of claim 1 , wherein the RF input signal is a signal in the frequency range from 15 GHz to 75 GHz.
3. The miniaturized millimeter wave hybrid of claim 1 , wherein the first port is an Input port, the second port is an Isolated port, the third port is a Through port, and the fourth port is a Coupled port, wherein the second port is connected to a termination.
4. The miniaturized millimeter wave hybrid of claim 1 , wherein the phase difference between the RF signal output by the third port and the RF signal output by the fourth port relative to the input RF signal is 90-degree.
5. The miniaturized millimeter wave hybrid of claim 1 , wherein the width of each of the first metal line and the second metal line and the spacing between the first metal line and the second metal line are set to their respective allowable minimum values.
6. The miniaturized millimeter wave hybrid of claim 5 , wherein the fabrication process is at least a 7-copper metal layers deep sub-micron used for a 65 nanometer CMOS fabrication.
7. The miniaturized millimeter wave hybrid of claim 1 , wherein the resulting structure is characterized by a strong mutual inductance and capacitance of the first and second metal lines.
8. The miniaturized millimeter wave hybrid of claim 1 , wherein the second metal line is fabricated on the second metal layer only in sections where the first metal line crosses the second metal line.
9. The miniaturized millimeter wave hybrid of claim 8 , wherein the second metal layer is a metal layer directly under the first metal layer, wherein the first metal layer is an uppermost layer of the multilayer substrate.
10. The miniaturized millimeter wave hybrid of claim 4 , wherein a frequency of the input signal is 60 GHz, the first number of turns is 1.75 and the second number of turns is 1.5, a length of each of the first and second metal lines is 275 micron, a width of the first metal line is 3 micron and a width of the second metal line is 0.5 micron.
11. The miniaturized millimeter wave hybrid of claim 4 , wherein a frequency of the input signal is 30 GHz, the first number of turns is 1.75 and the second number of turns is 2, a length of the first line is 560 micron and a length of a second metal line is 490 micron, a width of the first metal line is 3 micron and a width of the second metal line is 0.5 micron.
12. The miniaturized millimeter wave hybrid of claim 10 , wherein the miniaturized millimeter wave hybrid is integrated in an RF integrated circuit (RFIC) adapted for 60 GHz band applications.
13. The miniaturized millimeter wave hybrid of claim 1 , wherein the uneven distribution of mutual inductance and capacitance is characterized by:
a first mutual inductance and capacitance in an upper portion of said millimeter wave hybrid between a single segment of said first metal line being in parallel with a single segment of said second metal line;
a second mutual inductance and capacitance in a lower portion of said millimeter wave hybrid between two segments of said first metal line being in parallel with two segments of said second metal line.