1. Field
Embodiments of the present invention relate to wireless radio frequency systems and, in particular, to baluns in wireless radio frequency systems.
2. Discussion of Related Art
Many wireless radio frequency (RF) applications, such as televisions, wireless telephones, and personal digital assistants (PDAs), receive unbalanced, single-ended signals and convert them to balanced, differential signals for downstream processing. A line is unbalanced when the signal being transmitted over the line has ground as its reference potential. A line is balanced when the signal being transmitted over the line does not have ground as its reference potential.
Baluns are commonly used to convert unbalanced, single-ended signals to balanced, differential signals with each signal having substantially the same magnitude but being one hundred eighty degrees out of phase with each other. For example, it is typical to fine a balun is placed between a twisted pair of wires on a television antenna (balanced line) and the coaxial cable going to the television (unbalanced line). The term balun comes from combining the word “balanced” with the word “unbalanced.”
Baluns used in many present-day applications such as small, hand-held RF wireless devices have limitations, however. For example, they tend to be “expensive” components in that they are located on the dies of other components (e.g., on-die or on-silicon), and die space is very limited. Because they take up die space there is less space available for other on-die components.
This also means that on-die baluns also are limited in size in an effort to accommodate other on-die components. Size limitations limit the signal-to-noise ratio (SNR), signal sensitivity, and the quality (Q) factor of baluns.
Baluns used in many present-day applications such as small, hand-held RF wireless devices also tend to be low performance components. This is because as current flows through the small traces of the baluns some of the signal magnitude is lost due to heat dissipation and lossiness. The balanced, differential signal is thus degraded.
In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally equivalent elements. The drawing in which an element first appears is indicated by the leftmost digit(s) in the reference number, in which:
In the illustrated embodiment, the balun 102 is coupled to an antenna 108 via a single-ended, unbalanced line 110, and to the die 104 via balanced, differential lines 112 and 114. In operation, the antenna 108 may receive a single-ended, unbalanced radio frequency (RF) signal, the balun 102 may convert the single-ended, unbalanced RF signal to a balanced, differential signal, and components (not shown) on the die 104 may process the balanced, differential signal according to the functions of the die 104.
The RF signal has an operating wavelength. In embodiments of the present invention the length of the metal trace 204 is three-quarters of the operating wavelength and the length of the metal trace 304 is one-quarter of the operating wavelength.
The metal traces 204 and 304 have end 208 and 308 to receive the single-ended, unbalanced RF signal and ends 210 and 310 to output the balanced, differential signal. In one embodiment, the signal output of the end 210 is one hundred eighty degrees out of phase with the signal output of the end 310, but is substantially the same magnitude as the signal output of the end 310.
In the illustrated embodiments, the metal traces 204 and 304 have a square shape, but embodiments are not so limited. For example, the metal traces 204 and 304 may be circular, spiral, rectangular, octagonal, or other suitable shape. After reading the description herein, a person of ordinary skill in the relevant art will readily recognize how to implement the metal traces 204 and 304 using other shapes.
In embodiments of the invention, the portions 202 and 302 may be fabricated using known packaging transmission line etching technology. For example, the base 206 may be a dielectric material (e.g., organic, low loss, ceramic, FR-4)). The metal trace 204 may be fabricated by depositing a layer of copper on the surface of the dielectric material. Portions of the copper may be etched away to leave the metal trace 204 (or other coil, transmission line, or inductor having the length and pattern for the particular application).
In embodiments, the total electrical length of the metal trace 204, which includes interconnects from the die bumps 506 and 508 to the metal traces 204 and/or 304, may be adjusted to control any phase imbalance. In one embodiment, the spacing between and width of the metal traces 204 and 304 may determine the magnitude of any phase imbalance the balun 102. Also, in one embodiment, the spaces between and width of the metal traces 204 and 304 may be designed such that the balun 102 may be implemented as an impedance transformer. After reading the description herein, a person of ordinary skill in the relevant art will readily recognize how to adjust the spacing and/or widths of the metal traces 204 and 304 to implement the balun 102 as an impedance transformer.
Of course, the process 600 is only an example process and other processes may be used to implement embodiments of the present invention. A machine-accessible medium with machine-readable instructions thereon may be used to cause a machine (e.g., a processor) to perform the process 600.
In a block 602, the portion 202 is disposed on the package 106.
In a block 604, the portion 302 is disposed on the package 106.
In a block 606, the portions 202 and 302 are coupled to die bumps 506 and 508. In one embodiment, the package 106 has multiple layers, such as eight or ten layers, for example, and the portions 202 and 302 are etched at the bottom layer.
Embodiments of the present invention may be implemented using hardware, software, or a combination thereof. In implementations using software, the software may be stored on a machine-accessible medium.
A machine-accessible medium includes any mechanism that provides (i.e., stores and/or transmits) information in a form accessible by a machine (e.g., a computer, network device, personal digital assistant, manufacturing tool, any device with a set of one or more processors, etc.). For example, a machine-accessible medium includes recordable and non-recordable media (e.g., read only memory (ROM), random access memory (RAM), magnetic disk storage media, optical storage media, flash memory devices, etc.), as well as electrical, optical, acoustic, or other form of propagated signals (e.g., carrier waves, infrared signals, digital signals, etc.).
In the above description, numerous specific details, such as particular processes, materials, devices, and so forth, are presented to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the embodiments of the present invention may be practiced without one or more of the specific details, or with other methods, components, etc. In other instances, well-known structures or operations are not shown or described in detail to avoid obscuring the understanding of this description.
Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, process, block, or characteristic described in connection with an embodiment is included in at least one embodiment of the present invention. Thus, the appearance of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification does not necessarily mean that the phrases all refer to the same embodiment. The particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
The terms used in the following claims should not be construed to limit embodiments of the invention to the specific embodiments disclosed in the specification and the claims. Rather, the scope of embodiments of the invention is to be determined entirely by the following claims, which are to be construed in accordance with established doctrines of claim interpretation.
Number | Name | Date | Kind |
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6424227 | El-Sharawy | Jul 2002 | B1 |
6803835 | Frank | Oct 2004 | B1 |
Number | Date | Country | |
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20060001501 A1 | Jan 2006 | US |