PATENT DOCUMENT

Publication Number: US-12009849-B2
Application Number: US-202117411892-A
Country: US
Kind Code: B2

Title: Distributed-element filter for mmWave frequencies

Abstract:
Frequency-filtering circuitry is disclosed that rejects power of a wireless signal having an undesired frequency while causing a decreased power loss to a wireless signal having a desired frequency using distributed elements, rather than lumped elements. The frequency-filtering circuitry may reject at least 5 decibels of power of a wireless signal having a frequency over 32 gigahertz, while causing a power loss of at most 1.1 decibels to a wireless signal having a frequency lower than 29.5 gigahertz. The frequency-filtering circuitry may include a main branch, a first parallel branch coupled and parallel to the main branch via a first connecting trace, and a second parallel branch coupled and parallel to the main branch via a second connecting trace. The first connecting trace intersects the main branch and the first parallel branch, and the second connecting trace intersects the main branch and the second parallel branch.

Claims:
The invention claimed is: 
     
       1. Frequency-filtering circuitry comprising:
 a main branch comprising a first terminal and a second terminal, the main branch extending in a first direction, a distance between the first terminal and the second terminal being between 700 and 900 micrometers; 
 a first branch coupled to the main branch at the first terminal via a first connecting trace, the first branch extending in a same direction as the main branch, and the first connecting trace intersecting the main branch and the first branch; and 
 a second branch coupled to the main branch at the second terminal via a second connecting trace, the second branch extending in a second direction, the second direction being different from the first direction, and the second connecting trace intersecting the main branch and the second branch. 
 
     
     
       2. The frequency-filtering circuitry of  claim 1 , wherein the first branch extends in the same direction as the main branch from the first terminal toward the second terminal. 
     
     
       3. The frequency-filtering circuitry of  claim 1 , wherein the second branch extends in the second direction from the second terminal toward the first terminal. 
     
     
       4. The frequency-filtering circuitry of  claim 1 , wherein the first branch and the second branch are each longer than the distance between the first terminal and the second terminal. 
     
     
       5. The frequency-filtering circuitry of  claim 1 , wherein the first branch and the second branch are each between 800 and 1100 micrometers. 
     
     
       6. The frequency-filtering circuitry of  claim 1 , wherein the frequency-filtering circuitry is configured to reject at least 5 decibels of power of a wireless signal having a frequency over 32 gigahertz. 
     
     
       7. The frequency-filtering circuitry of  claim 1 , wherein the frequency-filtering circuitry is configured to cause a power loss of at most 1.1 decibels to a wireless signal having a frequency lower than 29.5 gigahertz. 
     
     
       8. The frequency-filtering circuitry of  claim 1 , wherein a length of the second branch is greater than or equal to a length of the main branch. 
     
     
       9. The frequency-filtering circuitry of  claim 1 , wherein a length of the second branch is less than a length of the main branch. 
     
     
       10. The frequency-filtering circuitry of  claim 1 , wherein a length of the first branch is less than a length of the main branch. 
     
     
       11. A transceiver, comprising:
 an amplifier; and 
 frequency-filtering circuitry coupled to the amplifier, the frequency-filtering circuitry comprising:
 a main branch comprising a first terminal and a second terminal, the main branch extending in a first direction, a distance between the first terminal and the second terminal being between 700 and 900 micrometers; 
 a first branch coupled to the main branch at the first terminal via a first connecting trace, the first branch extending in a same direction as the main branch, and the first connecting trace intersecting the main branch and the first branch; and 
 a second branch coupled to the main branch at the second terminal via a second connecting trace, the second branch extending in a second direction, the second direction being different from the first direction, and the second connecting trace intersecting the main branch and the second branch. 
 
 
     
     
       12. The transceiver of  claim 11 , wherein a height of the frequency-filtering circuitry comprises 15 micrometers or less. 
     
     
       13. The transceiver of  claim 11 , wherein a width of the frequency-filtering circuitry is within 206 micrometers. 
     
     
       14. The transceiver of  claim 11 , wherein a length of the first branch is less than a length of the main branch. 
     
     
       15. The transceiver of  claim 11 , wherein a length of the second branch is less than the length of the main branch. 
     
     
       16. The transceiver of  claim 11 , wherein a length of the second branch is greater than or equal to the length of the main branch. 
     
     
       17. An electronic device, comprising:
 one or more antennas; and 
 a transceiver electrically coupled to the one or more antennas, the transceiver comprising:
 a main branch comprising a first terminal and a second terminal, the main branch extending in a first direction, a distance between the first terminal and the second terminal being between 700 and 900 micrometers; 
 a first branch coupled to the main branch at the first terminal via a first connecting trace, the first branch extending in a same direction as the main branch, and the first connecting trace intersecting the main branch and the first branch; and 
 a second branch coupled to the main branch at the second terminal via a second connecting trace, the second branch extending in a second direction, the second direction being different from the first direction, and the second connecting trace intersecting the main branch and the second branch. 
 
 
     
     
       18. The electronic device of  claim 17 , further comprising a printed circuit board having at least a first layer, a second layer, and an intermediate layer disposed between the first layer and the second layer, wherein the main branch, the first branch, and the second branch are disposed on the intermediate layer. 
     
     
       19. The electronic device of  claim 18 , wherein the intermediate layer comprises a routing channel in which the main branch, the first branch, and the second branch are disposed. 
     
     
       20. The electronic device of  claim 17 , wherein the main branch is configured to provide a series inductance, the first branch is configured to provide a first inductance, and the second branch is configured to provide a second inductance.

Description:
BACKGROUND 
     The present disclosure relates generally to wireless communication and more specifically to filtering noise at undesired frequencies from a wireless signal. 
     In a mobile communication device, a transceiver may transmit and receive wireless signals. For example, the transceiver may enable communication over millimeter wave (mmWave) frequencies (e.g., 24.25 gigahertz (GHz) and above). However, spurious emissions in the mmWave frequencies, such as those at greater than 32 GHz caused by satellite and/or space communications, may cause interference with device communications. 
     SUMMARY 
     A summary of certain embodiments disclosed herein is set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of these certain embodiments and that these aspects are not intended to limit the scope of this disclosure. Indeed, this disclosure may encompass a variety of aspects that may not be set forth below. 
     In one embodiment, frequency-filtering circuitry includes a main branch and a first branch coupled to the main branch via a first connecting trace. The first branch extends in a same direction as the main branch, and the first connecting trace is intersects the main branch and the first branch. The frequency-filtering circuitry also includes a second branch coupled to the main branch via a second connecting trace. The second branch extends in an opposite direction with respect to the main branch, and the second connecting trace intersects the main branch and the second branch. 
     In another embodiment, a transceiver includes an amplifier and a filter electrically coupled to the amplifier. The filter includes a series branch, a first parallel branch coupled to the series branch via a first connecting trace, and a second parallel branch coupled to the series branch via a second connecting trace. The first parallel branch and the second parallel branch are each parallel to the series branch. Additionally, a distance between the first parallel branch and the second parallel branch is within 122 micrometers. 
     In yet another embodiment, an electronic device includes a printed circuit board having at least a first layer, a second layer, and an intermediate layer disposed between the first layer and the second layer. The electronic device also includes one or more antennas, and a transceiver coupled to the one or more antennas. The transceiver includes filtering circuitry disposed on the intermediate layer. The filtering circuitry includes a series circuit trace, a first circuit trace coupled to the series circuit trace via a first connecting trace, and a second circuit trace coupled to the series circuit trace via a second connecting trace. The first circuit trace and the second circuit trace are each alongside the series circuit trace. 
     Various refinements of the features noted above may exist in relation to various aspects of the present disclosure. Further features may also be incorporated in these various aspects as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to one or more of the illustrated embodiments may be incorporated into any of the above-described aspects of the present disclosure alone or in any combination. The brief summary presented above is intended only to familiarize the reader with certain aspects and contexts of embodiments of the present disclosure without limitation to the claimed subject matter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various aspects of this disclosure may be better understood upon reading the following detailed description and upon reference to the drawings described below in which like numerals refer to like parts. 
         FIG.  1    is a block diagram of an electronic device, according to embodiments of the present disclosure; 
         FIG.  2    is a functional diagram of the electronic device of  FIG.  1   , according to embodiments of the present disclosure; 
         FIG.  3    is a schematic diagram of a transmitter of the electronic device of  FIG.  1   , according to embodiments of the present disclosure; 
         FIG.  4    is a schematic diagram of a receiver of the electronic device of  FIG.  1   , according to embodiments of the present disclosure; 
         FIG.  5    is diagram of a low pass filter according to embodiments of the present disclosure; 
         FIG.  6    is a circuit diagram of a lumped-element approximation of the low pass filter of  FIG.  5   , according to embodiments of the present disclosure; 
         FIG.  7    is a plot showing performance of the filter of  FIG.  5   , according to embodiments of the present disclosure; 
         FIG.  8    is a table illustrating in-band loss and out-of-band rejection with varying main branch length, according to embodiments of the present disclosure; 
         FIG.  9    is a table illustrating in-band loss and out-of-band rejection with varying parallel branch length, according to embodiments of the present disclosure; 
         FIG.  10    is a perspective diagram of a layer of a printed circuit board having multiple filters of  FIG.  5   , according to embodiments of the present disclosure; 
         FIG.  11    is an angled view of the layer of  FIG.  10   , with a focus on the filter of  FIG.  5   , according to embodiments of the present disclosure; 
         FIG.  12    is a perspective diagram of a printed circuit board having multiple layers, according to embodiments of the present disclosure; 
         FIG.  13    is a diagram illustrating the filter of  FIG.  5    disposed in a routing channel of the layer of  FIG.  10   , according to embodiments of the present disclosure; 
         FIG.  14    is a diagram of a band stop filter, according to embodiments of the present disclosure; 
         FIG.  15 A  is a diagram of a top view of a first layer of a printed circuit board having the filter of  FIG.  14   , according to embodiments of the present disclosure; 
         FIG.  15 B  is a diagram of a top view of a second layer of the printed circuit board having the filter of  FIG.  14   , according to embodiments of the present disclosure; 
         FIG.  15 C  is a diagram of a top view of a third layer of the printed circuit board having the filter of  FIG.  14   , according to embodiments of the present disclosure; 
         FIG.  15 D  is a diagram of a top view of a fourth layer of the printed circuit board having the filter of  FIG.  14   , according to embodiments of the present disclosure; 
         FIG.  15 E  is a diagram of a top view of a fifth layer of the printed circuit board having the filter of  FIG.  14   , according to embodiments of the present disclosure; 
         FIG.  15 F  is a diagram of a side view of the printed circuit board having the filter of  FIG.  14   , according to embodiments of the present disclosure; 
         FIG.  16    is a plot showing power loss of the filter of  FIG.  14    with varying frequency, according to embodiments of the present disclosure; 
         FIG.  17    is a diagram of a band stop filter, according to embodiments of the present disclosure; 
         FIG.  18    is a circuit diagram of a lumped-element approximation of the filter of  FIG.  17   , according to embodiments of the present disclosure; 
         FIG.  19    is a plot showing power loss of the filter of  FIG.  17    with varying frequency, according to embodiments of the present disclosure; 
         FIG.  20    is a diagram of a band stop filter with open shunt elements, according to embodiments of the present disclosure; 
         FIG.  21    is a plot showing power loss of the filter of  FIG.  20    with varying frequency, according to embodiments of the present disclosure; 
         FIG.  22    is a diagram of a band stop filter with open shunt elements, according to embodiments of the present disclosure; 
         FIG.  23    is a plot showing power loss of the filter of  FIG.  22    with varying frequency, according to embodiments of the present disclosure 
         FIG.  24    is a diagram of a band stop filter with open shunt elements, according to embodiments of the present disclosure; and 
         FIG.  25    is a plot showing power loss of the filter of  FIG.  24    with varying frequency, according to embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS 
     One or more specific embodiments will be described below. In an effort to provide a concise description of these embodiments, not all features of an actual implementation are described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure. 
     When introducing elements of various embodiments of the present disclosure, the articles “a,” “an,” and “the” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Additionally, it should be understood that references to “one embodiment” or “an embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. Use of the term “approximately,” “near,” “about,” “close to,” and/or “substantially” should be understood to mean including close to a target (e.g., design, value, amount), such as within a margin of any suitable or contemplatable error (e.g., within 0.1% of a target, within 1% of a target, within 5% of a target, within 10% of a target, within 25% of a target, and so on). 
     This disclosure is directed to filtering noise at undesired frequencies from a wireless signal. In a mobile communication device, a transceiver may transmit and receive wireless signals. For example, the transceiver may enable communication over millimeter wave (mmWave) frequencies (e.g., 24.25 gigahertz (GHz) and above). However, spurious emissions in the mmWave frequencies, such as those at approximately 32.3 GHz caused by satellite and/or space communications, may cause interference with device communications. 
     Embodiments herein provide frequency-filtering circuitry that rejects power of a wireless signal having an undesired frequency, while causing a decreased power loss to a wireless signal having a desired frequency. The frequency-filtering circuitry includes distributed elements rather than lumped elements (e.g., capacitors, inductors, resistors, and so on). In particular, the frequency-filtering circuitry may include a low pass filter that rejects at least 5 decibels of power of a wireless signal having a frequency over 32 gigahertz, while causing a power loss of at most 1.1 decibels to a wireless signal having a frequency lower than 29.5 gigahertz. The frequency-filtering circuitry includes a main branch, a first branch coupled to and extending in a same direction as the main branch via a first connecting trace, and a second branch coupled to and extending in an opposite direction with respect to the main branch via a second connecting trace. The first connecting trace intersects to the main branch and the first branch, and the second connecting trace is intersects the main branch and the second branch. 
     In another embodiment, frequency-filtering circuitry may include a band stop filter that rejects at least 3.5 decibels of power of a wireless signal having a frequency of at least 36.4 gigahertz, while causing a power loss of at most 0.33 decibels to a wireless signal having a frequency lower than 29.5 gigahertz. In particular, the frequency-filtering circuitry includes a main branch, a first circle trace coupled to the main branch via a first connecting trace, and a second circle trace coupled to the main branch via a second connecting trace. The main branch may be disposed on a first layer of a circuit board, and the first and second circle traces may be disposed on a second layer of the circuit board. The first connecting trace intersects the main branch, and the second connecting trace intersects the main branch. 
     In an additional or alternative embodiment, frequency-filtering circuitry may include a band stop filter that rejects at least 5.4 decibels of power of a wireless signal having a frequency between 36.4 and 41.2 gigahertz, while causing a power loss of at most 0.34 decibels to a wireless signal having a frequency lower than 29.5 gigahertz. In particular, the frequency-filtering circuitry includes a main branch, a first parallel branch coupled to and parallel to the main branch via a first connecting trace, and a second parallel branch coupled to and parallel to the first parallel branch via a second connecting trace. The second parallel branch may be coupled to an electrical ground, providing a low impedance pathway for higher frequency signals (e.g., between 36.4 and 41.2 GHz), thus acting as a shunt. The first connecting trace intersects the main branch and the first parallel branch, and the second connecting trace intersects the first parallel branch and the second parallel branch. 
     In yet another embodiment, frequency-filtering circuitry may include a band stop filter with an open shunt element that rejects at least 5.3 decibels of power of a wireless signal having a frequency between 36.4 and 50 gigahertz, while causing a power loss of at most 0.28 decibels to a wireless signal having a frequency lower than 29.5 gigahertz. In particular the frequency-filtering circuitry includes a main branch, a first branch coupled to and alongside the main branch via a first connecting trace, and a second branch coupled to and alongside the main branch via a second connecting trace. The first connecting trace intersects the main branch and the first branch, and the second connecting trace intersects the main branch and the second branch. 
     Because the disclosed frequency-filtering circuitries reject power of wireless signals having a frequency of at least 36.4 gigahertz and cause a decreased power loss at signals having a frequency lower than 29.5 gigahertz, they may be particularly suited for millimeter wave (mmWave) frequency range (e.g., 24.25-300 gigahertz (GHz)) applications. Moreover, using distributed elements, instead of lumped elements, may save space when utilized for mmWave applications. Furthermore, due to height dimensions of the lumped elements, the frequency-filtering circuitry may be moved to deeper (e.g., intermediate) circuit board layers, avoiding the need to dispose the circuitry on a top or surface layer, which may decrease path loss (e.g., from routing traces in deeper layers to the top or surface layer and back). Additionally, lumped element filters for higher frequency (e.g., mmWave) applications may be more expensive (e.g., than lower frequency applications due to lower demand for the components and manufacturing complexities inherent in the higher frequency filters. 
       FIG.  1    is a block diagram of an electronic device  10 , according to embodiments of the present disclosure. The electronic device  10  may include, among other things, one or more processors  12  (collectively referred to herein as a single processor for convenience, which may be implemented in any suitable form of processing circuitry), memory  14 , nonvolatile storage  16 , a display  18 , input structures  22 , an input/output (I/O) interface  24 , a network interface  26 , and a power source  29 . The various functional blocks shown in  FIG.  1    may include hardware elements (including circuitry), software elements (including machine-executable instructions) or a combination of both hardware and software elements (which may be referred to as logic). The processor  12 , memory  14 , the nonvolatile storage  16 , the display  18 , the input structures  22 , the input/output (I/O) interface  24 , the network interface  26 , and/or the power source  29  may each be communicatively coupled directly or indirectly (e.g., through or via another component, a communication bus, a network) to one another to transmit and/or receive data between one another. It should be noted that  FIG.  1    is merely one example of a particular implementation and is intended to illustrate the types of components that may be present in electronic device  10 . 
     By way of example, the electronic device  10  may include any suitable computing device, including a desktop or notebook computer (e.g., in the form of a MacBook®, MacBook® Pro, MacBook Air®, iMac®, Mac® mini, or Mac Pro® available from Apple Inc. of Cupertino, California), a portable electronic or handheld electronic device such as a wireless electronic device or smartphone (e.g., in the form of a model of an iPhone® available from Apple Inc. of Cupertino, California), a tablet (e.g., in the form of a model of an iPad® available from Apple Inc. of Cupertino, California), a wearable electronic device (e.g., in the form of an Apple Watch® by Apple Inc. of Cupertino, California), and other similar devices. It should be noted that the processor  12  and other related items in  FIG.  1    may be generally referred to herein as “data processing circuitry.” Such data processing circuitry may be embodied wholly or in part as software, hardware, or both. Furthermore, the processor  12  and other related items in  FIG.  1    may be a single contained processing module or may be incorporated wholly or partially within any of the other elements within the electronic device  10 . The processor  12  may be implemented with any combination of general-purpose microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate array (FPGAs), programmable logic devices (PLDs), controllers, state machines, gated logic, discrete hardware components, dedicated hardware finite state machines, or any other suitable entities that may perform calculations or other manipulations of information. The processors  12  may include one or more application processors, one or more baseband processors, or both, and perform the various functions described herein. 
     In the electronic device  10  of  FIG.  1   , the processor  12  may be operably coupled with a memory  14  and a nonvolatile storage  16  to perform various algorithms. Such programs or instructions executed by the processor  12  may be stored in any suitable article of manufacture that includes one or more tangible, computer-readable media. The tangible, computer-readable media may include the memory  14  and/or the nonvolatile storage  16 , individually or collectively, to store the instructions or routines. The memory  14  and the nonvolatile storage  16  may include any suitable articles of manufacture for storing data and executable instructions, such as random-access memory, read-only memory, rewritable flash memory, hard drives, and optical discs. In addition, programs (e.g., an operating system) encoded on such a computer program product may also include instructions that may be executed by the processor  12  to enable the electronic device  10  to provide various functionalities. 
     In certain embodiments, the display  18  may facilitate users to view images generated on the electronic device  10 . In some embodiments, the display  18  may include a touch screen, which may facilitate user interaction with a user interface of the electronic device  10 . Furthermore, it should be appreciated that, in some embodiments, the display  18  may include one or more liquid crystal displays (LCDs), light-emitting diode (LED) displays, organic light-emitting diode (OLED) displays, active-matrix organic light-emitting diode (AMOLED) displays, or some combination of these and/or other display technologies. 
     The input structures  22  of the electronic device  10  may enable a user to interact with the electronic device  10  (e.g., pressing a button to increase or decrease a volume level). The I/O interface  24  may enable electronic device  10  to interface with various other electronic devices, as may the network interface  26 . In some embodiments, the I/O interface  24  may include an I/O port for a hardwired connection for charging and/or content manipulation using a standard connector and protocol, such as the Lightning connector provided by Apple Inc. of Cupertino, California, a universal serial bus (USB), or other similar connector and protocol. The network interface  26  may include, for example, one or more interfaces for a personal area network (PAN), such as an ultra-wideband (UWB) or a BLUETOOTH® network, for a local area network (LAN) or wireless local area network (WLAN), such as a network employing one of the IEEE 802.11x family of protocols (e.g., WI-FI®), and/or for a wide area network (WAN), such as any standards related to the Third Generation Partnership Project (3GPP), including, for example, a 3 rd  generation (3G) cellular network, universal mobile telecommunication system (UMTS), 4 th  generation (4G) cellular network, long term evolution (LTE®) cellular network, long term evolution license assisted access (LTE-LAA) cellular network, 5th generation (5G) cellular network, and/or New Radio (NR) cellular network, a satellite network, and so on. In particular, the network interface  26  may include, for example, one or more interfaces for using a Release-15 cellular communication standard of the 5G specifications that include the millimeter wave (mmWave) frequency range (e.g., 24.25-300 gigahertz (GHz)) and/or any other cellular communication standard release (e.g., Release-16, Release-17, any future releases) that define and/or enable frequency ranges used for wireless communication. The network interface  26  of the electronic device  10  may allow communication over the aforementioned networks (e.g., 5G, Wi-Fi, LTE-LAA, and so forth). 
     The network interface  26  may also include one or more interfaces for, for example, broadband fixed wireless access networks (e.g., WIMAX®), mobile broadband Wireless networks (mobile WIMAX®), asynchronous digital subscriber lines (e.g., ADSL, VDSL), digital video broadcasting-terrestrial (DVB-T®) network and its extension DVB Handheld (DVB-H®) network, ultra-wideband (UWB) network, alternating current (AC) power lines, and so forth. 
     As illustrated, the network interface  26  may include a transceiver  30 . In some embodiments, all or portions of the transceiver  30  may be disposed within the processor  12 . The transceiver  30  may support transmission and receipt of various wireless signals via one or more antennas, and thus may include a transmitter and a receiver. In particular, the transceiver may enable bidirectional communication over a single path while separating signals traveling in each direction from one another (e.g., via a duplexer, such as an electrical balanced duplexer, a double balanced duplexer, or any other suitable form of duplexer). For example, the transceiver  30  may enable frequency division duplexing (FDD), such that the transceiver  30  may isolate a transmitter of the electronic device  10  from a received signal of a first frequency band while isolating a receiver of the electronic device  10  from a transmission signal of a second frequency band (e.g., isolate the transmitter from the receiver, and vice versa). 
     The power source  29  of the electronic device  10  may include any suitable source of power, such as a rechargeable lithium polymer (Li-poly) battery and/or an alternating current (AC) power converter. In certain embodiments, the electronic device  10  may take the form of a computer, a portable electronic device, a wearable electronic device, or other type of electronic device. 
       FIG.  2    is a functional diagram of the electronic device  10  of  FIG.  1   , according to embodiments of the present disclosure. As illustrated, the processor  12 , the memory  14 , the transceiver  30 , a transmitter  52 , a receiver  54 , and/or antennas  55  (illustrated as  55 A- 55 N, collectively referred to as an antenna  55 ) may be communicatively coupled directly or indirectly (e.g., through or via another component, a communication bus, a network) to one another to transmit and/or receive data between one another. 
     The electronic device  10  may include the transmitter  52  and/or the receiver  54  that respectively enable transmission and reception of data between the electronic device  10  and an external device via, for example, a network (e.g., including base stations) or a direct connection. As illustrated, the transmitter  52  and the receiver  54  may be combined into the transceiver  30 . The electronic device  10  may also have one or more antennas  55 A- 55 N electrically coupled to the transceiver  30 . The antennas  55 A- 55 N may be configured in an omnidirectional or directional configuration, in a single-beam, dual-beam, or multi-beam arrangement, and so on. Each antenna  55  may be associated with a one or more beams and various configurations. In some embodiments, multiple antennas of the antennas  55 A- 55 N of an antenna group or module may be communicatively coupled a respective transceiver  30  and each emit radio frequency signals that may constructively and/or destructively combine to form a beam. The electronic device  10  may include multiple transmitters, multiple receivers, multiple transceivers, and/or multiple antennas as suitable for various communication standards. In some embodiments, the transmitter  52  and the receiver  54  may transmit and receive information via other wired or wireline systems or means. 
     As illustrated, the various components of the electronic device  10  may be coupled together by a bus system  56 . The bus system  56  may include a data bus, for example, as well as a power bus, a control signal bus, and a status signal bus, in addition to the data bus. The components of the electronic device  10  may be coupled together or accept or provide inputs to each other using some other mechanism. 
       FIG.  3    is a schematic diagram of the transmitter  52  (e.g., transmit circuitry), according to embodiments of the present disclosure. As illustrated, the transmitter  52  may receive outgoing data  60  in the form of a digital signal to be transmitted via the one or more antennas  55 . A digital-to-analog converter (DAC)  62  of the transmitter  52  may convert the digital signal to an analog signal, and a modulator  64  may combine the converted analog signal with a carrier signal to generate a radio wave. A first filter  68 A (e.g., filter circuitry and/or software) may remove then undesirable noise from the modulated signal. A power amplifier (PA)  66  receives signal the modulated signal from the modulator  64 . The power amplifier  66  may amplify the filtered signal to a suitable level to drive transmission of the signal via the one or more antennas  55 . A second filter  68 B may then remove undesirable noise from the amplified signal to generate transmitted data  70  to be transmitted via the one or more antennas  55 . The filters  68 A,  68 B (which may be collectively referred to as filter  68  herein) may include any suitable filters to remove the undesirable noise from the amplified signal, such as bandpass filters, bandstop filters, low pass filters, high pass filters, and/or decimation filters. Additionally, the transmitter  52  may include any suitable additional components not shown, or may not include certain of the illustrated components, such that the transmitter  52  may transmit the outgoing data  60  via the one or more antennas  55 . For example, the transmitter  52  may include a mixer and/or a digital up converter. As another example, the transmitter  52  may not include one or both of the filters  68  if the modulator  64  and/or the power amplifier  66  outputs a signal in or approximately in a desired frequency range or with reduced or minimal noise (such that filtering of the output signal may be unnecessary). 
       FIG.  4    is a schematic diagram of the receiver  54  (e.g., receive circuitry), according to embodiments of the present disclosure. As illustrated, the receiver  54  may receive received data  80  from the one or more antennas  55  in the form of an analog signal. A first filter  84 A (e.g., filter circuitry and/or software) may remove undesired noise from the analog signal, such as cross-channel interference. The filter  84 A may also remove additional signals received by the one or more antennas  55  which are at frequencies other than the desired signal. A low noise amplifier (LNA)  82  may amplify the filtered analog signal to a suitable level for the receiver  54  to process. Similar to the first filter  84 A, the second filter  84 B may remove undesired noise and/or additional signals received by the one or more antennas  55  which are at frequencies other than the desired signal from the amplified signal. The filters  84 A,  84 B (collectively referred to as the filter  84  herein) may include any suitable filters to remove the undesired noise or signals from the received signal, such as bandpass filters, bandstop filters, low pass filters, high pass filters, and/or decimation filters. A demodulator  86  may remove a radio frequency envelope and/or extract a demodulated signal from the filtered signal for processing. An analog-to-digital converter (ADC)  88  may receive the demodulated analog signal and convert the signal to a digital signal of incoming data  90  to be further processed by the electronic device  10 . Additionally, the receiver  54  may include any suitable additional components not shown, or may not include certain of the illustrated components, such that the receiver  54  may receive the received data  80  via the one or more antennas  55 . For example, the receiver  54  may include a mixer and/or a digital down converter. 
     Embodiments herein provide frequency-filtering circuitry (e.g., a filter) that rejects power of a wireless signal having an undesired frequency while causing a decreased power loss to a wireless signal having a desired frequency using distributed elements, rather than lumped elements (e.g., capacitors, inductors, resistors, and so on). That is, the filter may be made (e.g., solely) of circuit trace, a conducting track on a printed circuit board that connects components electrically and allows electric current to flow with little resistance. For example, the circuit trace may be made of copper, aluminum, or any other suitable conductive material. The filter rejects power of a wireless signal having an undesired frequency, while causing a decreased power loss to a wireless signal having a desired frequency. In some embodiments, the filter may be representative of the filter  68 A and/or the filter  68 B of the transmitter  52  and/or the filter  84 A and/or the filter  68 B of the receiver  54 . 
       FIG.  5    is diagram of a filter  100  (e.g., a low pass filter) according to embodiments of the present disclosure. The filter  100  may include a distributed-element filter in which capacitance, inductance, and/or resistance are not localized in discrete capacitors, inductors, and/or resistors, as they are in conventional filters or lumped-element models (where these elements are considered to be “lumped” together in one place. A lumped-element filter, while arguably simpler in concept, may become increasingly unreliable with increasing frequency, as may be evidenced by relatively high mmWave frequencies (e.g., 24.25 GHz and above). 
     As discussed above, the filter  100  may be made of (e.g., solely made of) circuit or signal trace. As such, the filter  100  may be printed on a layer of a printed circuit board (PCB) and conduct electrical signals. In particular, the filter  100  may be made of a flat, narrow part of copper foil that remains after etching the layer of the PCB. While described as made of copper, in additional or alternative embodiments, the filter  100  may be made of any other conductive material, such as aluminum. In some embodiments, the filter  100  may be made of 50Ω trace (such that a characteristic impedance of the trace is 50Ω), though the characteristic impedance may be any suitable impedance (e.g., greater than 0Ω, greater than 10Ω, greater than 50Ω, greater than 100Ω, and so on). 
     The filter  100  may include a first terminal  102  (e.g., an input terminal) and a second terminal  104  (e.g., an output terminal). While the first terminal  102  may couple to an electrical current source and the second terminal  104  may provide an output current, in alternative embodiments, this may be reversed. As illustrated, the terminals  102 ,  104  may have a length  105  (e.g., along an x- or length axis  106 ) and a width  107  (e.g., along a y- or width axis  108 ) that may be of any suitable dimensions that enable coupling to other circuitry (e.g., greater than 0 μm long and greater than 0 μm wide, greater than 10 μm long and greater than 10 μm wide, greater than 100 μm long and greater than 50 μm wide, greater than 200 μm long and greater than 100 μm wide, greater than 500 μm long and greater than 300 μm wide, and so on. For example, the length  105  of the terminals  102 ,  104  may be approximately 200 micrometers (μm) and the width  107  of the terminals  102 ,  104  may be approximately 62 μm. 
     The filter  100  may also include a main (e.g., series) branch or trace  110  coupling the first terminal  102  to the second terminal  104 . Varying dimensions of the main branch  110  may affect loss of a power of a signal passing through the filter  100  of a desired frequency (e.g., in-band loss) and rejection of a power of a signal to vary passing through the filter  100  of an undesired frequency (e.g., out-of-band rejection). In particular, increasing the length (e.g., along the x-axis  106 ) of the main branch  110  may increase the in-band loss, while increasing the out-of-band rejection, as discussed in further detail below. As illustrated, the main branch  110  may be approximately 755 μm long (e.g., along the x-axis  106 ) and approximately 42 μm wide (e.g., along the y-axis  108 ), though the main branch  110  may be of any suitable dimensions that enable effective in-band loss and out-of-band rejection performance and/or coupling to other circuitry (e.g., greater than 0 μm long and greater than 0 μm wide, greater than 10 μm long and greater than 10 μm wide, greater than 100 μm long and greater than 50 μm wide, greater than 200 μm long and greater than 100 μm wide, greater than 500 μm long and greater than 300 μm wide, and so on), as discussed in further detail below. 
     As illustrated, the filter  100  includes a first parallel branch or trace  112  coupled and parallel to, alongside, or coextensive with the main branch  110  via a first connecting trace  114 . As with the main branch  110 , varying dimensions of the first parallel branch  112  may affect in-band loss and out-of-band rejection. In particular, increasing the length (e.g., along the x-axis  106 ) of the first parallel branch  112  may increase the in-band loss, while increasing the out-of-band rejection, as discussed in further detail below. As illustrated, the first connecting trace  114  may couple to the main branch  110  at the first terminal  102 , and may be approximately orthogonal (e.g., 90°) to or intersect the main branch  110  and the first parallel branch  112 , though, in additional or alternative embodiments, the first connecting trace  114  may couple the main branch  110  to the first parallel branch  112  at any suitable angle (e.g., greater than 0°, greater than 30°, greater than 45°, greater than 60°, less than 120°, less than 135°, less than 150°, less than 180°, and so on). As such, the first parallel branch  112  may extend in a direction (e.g., a same direction as the main branch  110 ) from the first terminal  102  to the second terminal  104  (along the x-axis  106 ). The first connecting trace  114  may be approximately 72 μm long (e.g., along the y-axis  108 ) and approximately 42 μm wide (e.g., along the x-axis  106 ), though the first connecting trace  114  may be of any suitable dimensions that enable coupling the first parallel branch  112  to the main branch  110  (e.g., greater than 0 μm long and greater than 0 μm wide, greater than 10 μm long and greater than 10 μm wide, greater than 50 μm long and greater than 20 μm wide, greater than 100 μm long and greater than 50 μm wide, and so on). 
     As further illustrated, the first parallel branch  112  may have a length  115  (e.g., along the x-axis  106 ) and a width  116  (e.g., along the y-axis  108 ) that may be of any suitable dimensions that enable effective in-band loss and out-of-band rejection performance (e.g., greater than 0 μm long and greater than 0 μm wide, greater than 10 μm long and greater than 10 μm wide, greater than 100 μm long and greater than 50 μm wide, greater than 200 μm long and greater than 100 μm wide, greater than 500 μm long and greater than 300 μm wide, and so on). For example, the length  115  of the first parallel branch  112  may be approximately 968 μm, and the width  116  may be approximately 42 μm. As illustrated, the first parallel branch  112  is greater in length than the main branch  110 , and greater in length than a distance between the first terminal  102  and the second terminal  104 . Accordingly, while a first end of the first parallel branch  112  that couples to the first connecting trace  114  is aligned with the first terminal  102  (along the y-axis  108 ), a second end (or open stub) of the first parallel branch  112  may extend past the second terminal  104  (with respect to the y-axis  108 ). 
     Additionally, the filter  100  may include a second parallel branch or trace  117  coupled and parallel to, alongside, or coextensive with the main branch  110  via a second connecting trace  118 . In particular, the second connecting trace  118  may extend from the main branch  110  in an opposite direction (e.g., with respect to the y-axis  108  and/or with respect to the main branch  110 ) than the first connecting trace  114 . As with the main branch  110  and the first parallel branch  112 , varying dimensions of the second parallel branch  117  may affect in-band loss and out-of-band rejection. In particular, increasing the length (e.g., along the x-axis  106 ) of the second parallel branch  117  may increase the in-band loss, while increasing the out-of-band rejection, as discussed in further detail below. As illustrated, the second connecting trace  118  may couple to the main branch  110  at the second terminal  104 , and may be approximately orthogonal (e.g., 90°) to or intersect the main branch  110  and the second parallel branch  117 , though, in additional or alternative embodiments, the second connecting trace  118  may couple the main branch  110  to the second parallel branch  117  at any suitable angle (e.g., greater than 0°, greater than 30°, greater than 45°, greater than 60°, less than 120°, less than 135°, less than 150°, less than 180°, and so on). The second connecting trace  118  may be approximately 72 μm long (e.g., along the y-axis  108 ) and approximately 42 μm wide (e.g., along the x-axis  106 ), though the second connecting trace  118  may be of any suitable dimensions that enable coupling the second parallel branch  117  to the main branch  110  (e.g., greater than 0 μm long and greater than 0 μm wide, greater than 10 μm long and greater than 10 μm wide, greater than 50 μm long and greater than 20 μm wide, greater than 100 μm long and greater than 50 μm wide, and so on). As such, the second parallel branch  117  may extend in a direction from the second terminal  104  to the first terminal  102  (along the x-axis  106 ). 
     As further illustrated, the second parallel branch  117  may be approximately 968 μm long (e.g., along the x-axis  106 ) and approximately 42 μm wide (e.g., along the y-axis  108 ), though the second parallel branch  117  may be of any suitable dimensions that enable effective in-band loss and out-of-band rejection performance (e.g., greater than 0 μm long and greater than 0 μm wide, greater than 10 μm long and greater than 10 μm wide, greater than 100 μm long and greater than 50 μm wide, greater than 200 μm long and greater than 100 μm wide, greater than 500 μm long and greater than 300 μm wide, and so on), as discussed in further detail below. As illustrated, the second parallel branch  117  is greater in length than the main branch  110 , and greater in length than a distance between the first terminal  102  and the second terminal  104 . Accordingly, while a first end of the second parallel branch  117  that couples to the second connecting trace  118  is aligned with the second terminal  104  (along the y-axis  108 ), a second end (or open stub) of the second parallel branch  117  may extend past the first terminal  102  (with respect to the y-axis  108 ). 
     The main branch  110  and the first and second parallel branches  112 ,  117  may act as lumped elements to enable the filter  100  to reject power of a wireless signal having an undesired frequency while causing a decreased power loss to a wireless signal having a desired frequency. In particular, discontinuities of in the circuit trace of the transmission line of the filter  100  may present reactive impedances to a wavefront travelling along the filter  100 , and these reactances may be configured to serve as approximations for lumped inductors, capacitors or resonators, to result in desired filtering.  FIG.  6    is a circuit diagram of a lumped-element approximation of the filter  100 , according to embodiments of the present disclosure. The illustrated circuit  130  approximates the main branch  110  as an inductor  132  providing a series inductance L 1 , the first parallel branch  112  as a first capacitor  134  providing a first parallel capacitance C 1  coupled to a first end or node  136  of the inductor  132 , and the second parallel branch  117  as a second capacitor  138  providing a second parallel capacitance C 2  coupled to a second end or node  140  of the inductor  132 . 
     In particular, the filter  100  may act as a low pass filter that rejects at least 5 decibels (dB) of power of a wireless signal having a frequency over 32 gigahertz (GHz), while causing a power loss of at most 1.1 dB to a wireless signal having a frequency lower than 29.5 GHz.  FIG.  7    is a plot showing power loss  150  of the filter  100  with varying frequency, according to embodiments of the present disclosure. As illustrated, for frequencies lower than 29.5 GHz, the filter  100  causes a power loss  150  (e.g., an in-band loss) of less than 1.1 dB. For example, at 24.25 GHz, the filter  100  causes a power loss  150  of 0.53 dB, and at 29.5 GHz, the filter  100  causes a power loss of 1.06 dB. At frequencies over 32 GHz, the filter  100  causes a power loss  150  (e.g., an out-of-band rejection) of greater than 5 dB. For example, at 32.30 GHz, the filter  100  causes a power loss  150  of 5.2 dB. The performance shown in the plot may be particularly suited for mmWave operation that may occur over a frequency range at less than or equal to 29.5 GHz (e.g., on the n257 band (26.5-29.5 GHz), the n258 band (24.25-27.5 GHz), the n261 band (27.5-28.35 GHz), and so on) and experience noise at 31 GHz or greater (e.g., at 32.3 GHz as may be caused by satellite and/or space communication). 
     As a distributed-element filter, the filter  100 , both in-band loss and out-of-band rejection may increase with increasing lengths (e.g., along the x-axis  106 ) of the main branch  110 , the first parallel branch  112 , and/or the second parallel branch  117 .  FIG.  8    is a table illustrating in-band loss  160  and out-of-band rejection  162  with varying main branch length  164 , according to embodiments of the present disclosure. As an illustrative example, the filter  100  of  FIG.  5   , which is approximated by the first row  166  of the table, has a main branch length  164  of 755 μm, has an in-band loss of 1.11 dB (e.g., at approximately 29.5 GHz) and an out-of-band rejection  162  of 5.46 dB (e.g., at approximately 32.3 GHz).  FIG.  9    is a table illustrating in-band loss  170  and out-of-band rejection  172  with varying parallel branch length  174 , according to embodiments of the present disclosure. The parallel branch length  174  may refer to lengths of both the first parallel branch  112  and the second parallel branch  117  (e.g., where the lengths are approximately equal). As an illustrative example, the filter  100  of  FIG.  5   , which is approximated by the last row  176  of the table, has a parallel branch length  174  of 968 μm, has an in-band loss of 1.11 dB (e.g., at approximately 29.5 GHz) and an out-of-band rejection  162  of 5.46 dB (e.g., at approximately 32.3 GHz). 
       FIG.  10    is a perspective diagram of a top view (e.g., along a z- or depth axis  182 ) of a layer  180  of a printed circuit board having multiple filters  100 , according to embodiments of the present disclosure. As illustrated, the layer  180  includes eight filters  100 , though the layer  180  may include more or less filters  100  (e.g., one or more filters  100 , two or more filters  100 , ten or more filters  100 , and so on) based on the components of the layer  180 . For example, the printed circuit board may include or be coupled to one or more transmitters  52 , one or more receivers  54 , and so on, each of which may include one or more of the filters (e.g.,  68 ,  84 ) in the form of the low pass filter  100  disposed on the layer  180 .  FIG.  11    is an angled view of the layer  180 , with a focus on the filter  100 , according to embodiments of the present disclosure, for better clarity. 
     Because the filters  100  are made of distributed elements rather than lumped elements, the layer  180  may be an intermediate or deeper layer of the printed circuit board (e.g., that is in-between two other layers of the printed circuit board). That is, the printed circuit board may include at least two surface layers (e.g., a top layer and a bottom layer), and the layer  180  may be in-between the at least two surface layers (e.g., with respect to the z- or depth axis  182 ). 
       FIG.  12    is a perspective diagram of a printed circuit board (PCB)  200  having multiple layers  202  (illustrated as  202 A-C), according to embodiments of the present disclosure. As illustrated, the PCB  200  may have three layers  202 , but it should be understood that the PCB  200  may have any suitable number of layers (e.g., one, greater than one, greater than three, greater than five, greater than seven, and so on). In particular, the PCB  200  includes a top (with respect to the z-axis  182 ) or first surface layer  202 A, a bottom (with respect to the z-axis  182 ) or second surface layer  202 B, and an intermediate (with respect to the surface layers  202 A,  202 B) or deeper layer  202 C. While the filter  100  may be disposed on either surface layer  202 A,  202 B, due to the lower z-dimension or “height” (e.g., along the z-axis  182 ) of the filter  100 , the filter  100  may additionally or alternatively be disposed on the intermediate or deeper layer  202 C. For example, the height of the filter  100  may be 15 μm, though the filter  100  may be any suitable height that enables conduction of electrical signals, such as under 5 μm, under 10 μm, under 20 μm, and so on. On the other hand, the heights (e.g., along the z-axis  182 ) of lumped elements, such as resistors, capacitors, and inductors, may be on the order of greater than 50 μm, greater than 100 μm, greater than 200 μm, greater than 500 μm, and so on. The distances  204  between the layers  202  may be less than the heights of the lumped elements, such as 20 μm or less, 50 μm or less, 70 μm or less, 100 μm or less, and so on. The distances  204  may be filled with pre-preg, a composite material made from “pre-impregnated” fibers and a partially cured polymer matrix, such as epoxy, phenolic resin, and/or thermoplastic mixed with liquid rubbers or resins. The pre-preg may serve as a dielectric between the layers  202 . As such, using the distributed-element filter  100  enables disposing the filter  100  in an intermediate or deeper layer (e.g.,  202 C) of the PCB  200 , instead of limiting disposition of the filter  100  on a surface layer (e.g.,  202 A,  202 B). 
     Advantageously, disposing the filter  100  on an intermediate or deeper layer (e.g.,  202 C) of the PCB  200  may decrease path loss in wireless signals sent and/or received from the electronic device  10 . That is, the transceiver  30  (or other components of the transceiver  30 ) and/or the antennas  55  may be disposed on a surface layer (e.g.,  202 A,  202 B) of the PCB  200 , as these components typically have greater heights (e.g., along the z-axis  182 ). However, because the transceiver  30  and the antennas  55  may have different impedance characteristics, a wireless signals sent and/or received via the transceiver  30  and the antennas  55  may undergo impedance transformation, which may be performed by circuitry disposed on an intermediate or deeper layer (e.g.,  202 C). Thus, for lumped-element filters disposed on a surface layer (e.g.,  202 A) of the PCB  200 , the wireless signal may travel from the surface layer (e.g., from the transceiver  30  or the antennas  55 ) to an intermediate layer (e.g.,  202 C) (for impedance transformation) and to another surface layer (e.g.,  202 A) or back to the same surface layer (e.g.,  202 A) of the PCB  200  (e.g., to the antennas  55  or the transceiver  30 ) in order to be sent or received, causing some path loss to the wireless signal. For the distributed-element filter  100  disposed on an intermediate layer, the path loss may be decreased due to having to travel only between one surface layer and the intermediate layer for transmission or reception. 
     Moreover, the width (e.g., along the y-axis  108 ) of the filter  100  may be compact and space-efficient for placement in certain circuit board designs.  FIG.  13    is a diagram illustrating the filter  100  disposed in a routing channel  210  of the layer  180  (e.g., an intermediate layer  202 C) of the PCB  200 , according to embodiments of the present disclosure. The routing channel  210  may provide a channel in the layer  180  for circuit trace or other suitable conductors to be etched, disposed, and/or laminated onto. As illustrated, the filter  100  is disposed in the routing channel  210 , and coupled to a first component  212 A (via the first terminal  102 ) and a second component  212 B (via the second terminal  104 ). As shown in  FIG.  5   , each of the main branch  110 , the first parallel branch  112 , and the second parallel branch  117  may have a width (e.g., along the y-axis  108 ) of 42 μm. Moreover, each of the branches  110 ,  112 ,  117  are separated by a gap  214  of 40 μm. Additionally, the routing channel  210  is bordered (e.g., along a first edge  216  and a second edge  218 ) by electrical grounds  220 . To enable a buffer between the filter  100  (e.g., to enable effective operation of the filter  100  and/or to ensure that the filter  100  does not experience a ground fault or a short circuit), there is a gap  222  of 40 μm from the first parallel branch  112  to the ground  220 , and a gap  224  of 40 μm from the second parallel branch  117  to the ground  220 . Accordingly, the total width (e.g., along the y-axis  108 ) of the filter  100 , from the first parallel branch  112  to the second parallel branch  117 , is approximately 206 μm, and a distance  226  between the first parallel branch  112  and the second parallel branch  117  (e.g., along the y-axis  108 ) being approximately 122 μm. With the gaps  222 ,  224  that buffer the filter  100  from the ground  220 , the width is approximately 286 μm. That is, the filter  100  may conveniently fit into a routing channel  210  having a width of at least 286 μm. It should be understood that the various widths of the main branch  110 , the first parallel branch  112 , the second parallel branch  117 , the gaps  214 ,  222 ,  224 , and the routing channel  210  are used as examples, and any other suitable widths are contemplated (e.g., 1 μm or greater, 5 μm or greater, 10 μm or greater, 20 μm or greater, 40 μm or greater, 50 μm or greater, 100 μm or greater, 200 μm or greater, 300 μm or greater, and so on). 
       FIG.  14    is a diagram of a band stop filter  240 , according to embodiments of the present disclosure. As with the filter  100  of  FIG.  5   , the band stop filter  240  may include a distributed-element filter rather than a lumped-element filter. The filter  240  may include a first terminal  242  (e.g., an input terminal) and a second terminal  244  (e.g., an output terminal). While the first terminal  242  may couple to an electrical current source and the second terminal  244  may provide an output current, in alternative embodiments, this may be reversed. As with the filter  100  of  FIG.  5   , the terminals may be approximately 200 μm long (e.g., along an x- or length axis  106 ) and approximately 72 μm wide (e.g., along a y- or width axis  108 ), though the terminals  242 ,  244  may be of any suitable dimensions that enable coupling to other circuitry. 
     The filter  240  may also include a main (e.g., series) branch or trace  246  coupling the first terminal  242  to the second terminal  244 . Varying dimensions of the main branch  246  may affect loss of a power of a signal passing through the filter  240  of a desired frequency (e.g., out-of-band loss) and rejection of a power of a signal to vary passing through the filter  240  of an undesired frequency (e.g., in-band rejection). In particular, increasing the length (e.g., along the x-axis  106 ) of the main branch  246  may increase the out-of-band loss, while increasing the in-band rejection, as discussed in further detail below. The main branch  246  may be approximately 1.1 millimeters (mm) long or less (e.g., along the x-axis  106 ), and approximately 42 μm wide (e.g., along the y-axis  108 ), though the main branch  246  may be of any suitable dimensions that enable effective out-of-band loss and in-band rejection performance and/or coupling to other circuitry (e.g., greater than 0 μm long and greater than 0 μm wide, greater than 10 μm long and greater than 10 μm wide, greater than 100 μm long and greater than 50 μm wide, greater than 200 μm long and greater than 100 μm wide, greater than 500 μm long and greater than 300 μm wide, and so on), as discussed in further detail below. 
     As illustrated, the filter  240  includes a first circle trace  248  coupled to the main branch  246  via a first connecting trace  250 . As with the main branch  246 , varying dimensions of the first circle trace  248  may affect out-of-band loss and in-band rejection. In particular, increasing the radius of the first circle trace  248  may increase the out-of-band loss, while increasing the in-band rejection, as discussed in further detail below. As illustrated, the first connecting trace  250  may couple to the main branch  246  at the first terminal  242 , and may be approximately orthogonal (e.g., 90°) to or intersect the main branch  246 , though, in additional or alternative embodiments, the first connecting trace  250  may couple the main branch  246  to the first circle trace  248  at any suitable angle. In some embodiments, the first connecting trace  250  may have similar dimension as the first connecting trace  114  of the filter  100  of  FIG.  5   . As further illustrated, the first circle trace  248  may have a diameter of less than approximately 0.27 mm, though the first circle trace  248  may be of any suitable dimensions that enable effective out-of-band loss and in-band rejection performance (e.g., greater than 0 μm in diameter, greater than 10 μm in diameter, greater than 50 μm in diameter, greater than 100 μm in diameter, greater than 200 μm in diameter, greater than 500 μm in diameter, and so on), as discussed in further detail below. 
     Additionally, the filter  240  may include a second circle trace  252  coupled to the main branch  246  via a second connecting trace  254 . As with the main branch  246 , varying dimensions of the second circle trace  252  may affect out-of-band loss and in-band rejection. In particular, increasing the radius of the second circle trace  252  may increase the out-of-band loss, while increasing the in-band rejection. As illustrated, the second connecting trace  254  may couple to the main branch  246  at the second terminal  104 , and may be approximately orthogonal (e.g., 90°) to or intersect the main branch  246 , though, in additional or alternative embodiments, the second connecting trace  254  may couple the main branch  246  to the second circle trace  252  at any suitable angle. In some embodiments, the second connecting trace  254  may have similar dimensions as the first connecting trace  250 , and the second circle trace  252  may have similar dimensions as the first circle trace  248 . 
     Moreover, the first circle trace  248  may be disposed on a lower layer of a printed circuit board, and be coupled to a first trace rod  256  that extends from the first circle trace  248  upward (e.g., along the z-axis  182 ) to a higher layer of the printed circuit board. On the higher layer, the first trace rod  256  may be coupled to a first stub  258  via a third connecting trace  260 . As illustrated, the first stub  258  may extend from the third connecting trace  260  in a direction from the first terminal  242  to the second terminal  244  along the x-axis  106 . As with the first circle trace  248 , varying dimensions of the first stub  258  may affect out-of-band loss and in-band rejection. In particular, increasing a length of the first stub  258  may increase the out-of-band loss, while increasing the in-band rejection, as discussed in further detail below. As illustrated, the third connecting trace  260  may be approximately orthogonal (e.g., 90°) to or intersect the main branch  246  and the first stub  258 , though, in additional or alternative embodiments, the third connecting trace  260  may couple the main branch  246  to the first stub  258  via the first trace rod  256  at any suitable angle. In some embodiments, the third connecting trace  260  may have similar dimensions as the first connecting trace  250 . As further illustrated, the first stub  258  may have a length (along the x-axis  106 ) of less than approximately 0.27 mm, though the first stub  258  may be of any suitable dimensions that enable effective out-of-band loss and in-band rejection performance (e.g., greater than 0 μm, greater than 10 μm, greater than 50 μm, greater than 100 μm, greater than 200 μm, greater than 500 μm, and so on), as discussed in further detail below. 
     Moreover, the second circle trace  252  may be disposed on the lower layer of a printed circuit board, and be coupled to a second trace rod  262  that extends from the second circle trace  252  upward (e.g., along the z-axis  182 ) to the higher layer of the printed circuit board. On the higher layer, the second trace rod  262  may be coupled to a second stub  264  via a fourth connecting trace  266 . As illustrated, the second stub  264  may extend from the fourth connecting trace  266  in a direction from the second terminal  244  to first terminal  242  along the x-axis  106 . As with the second circle trace  252 , varying dimensions of the second stub  264  may affect out-of-band loss and in-band rejection. In particular, increasing a length of the second stub  264  may increase the out-of-band loss, while increasing the in-band rejection, as discussed in further detail below. As illustrated, the fourth connecting trace  266  may be approximately orthogonal (e.g., 90°) to or intersect the main branch  246  and the second stub  264 , though, in additional or alternative embodiments, the fourth connecting trace  266  may couple the main branch  246  to the second stub  264  via the second trace rod  262  at any suitable angle. In some embodiments, the fourth connecting trace  266  may have similar dimensions as the second connecting trace  254 . As further illustrated, the second stub  264  may have a length (along the x-axis  106 ) of less than a width  261  of an accommodating space  263  of approximately 0.27 mm, though the second stub  264  may be of any suitable dimensions that enable effective out-of-band loss and in-band rejection performance, as discussed in further detail below. 
     Additionally, an edge  265  of a channel  267  in which the main branch  246  is disposed may be a distance  268  of approximately 0.51 mm away from an edge  269  of the accommodating space  263  (along the y-axis  108 ), though the distance  268  may be of any suitable dimensions that enable effective out-of-band loss and in-band rejection performance (e.g., greater than 0.1 mm, greater than 0.25 mm, greater than 0.5 mm, greater than 1 mm, greater than 2 mm, greater than 5 mm, and so on). 
     While the first and second stubs  258 ,  264  may be disposed on a higher layer than the main branch  246 , there may be layers between the first and second stubs  258 ,  264  and the main branch  246 . For example,  FIGS.  15 A-F  illustrated distribution of the filter  240  among multiple layers of a printed circuit board. In particular,  FIG.  15 A  is a diagram of a top view of a first layer (Layer  1 )  270  of the printed circuit board having the filter  240 , according to embodiments of the present disclosure. The first layer  270  may be a top layer (with respect to the z-axis  182 ) of the printed circuit board, and may include vias  272  that couple circuitry of the first layer  270  to other layers. As illustrated, the first layer  270  may not include any components of the filter  240 . 
       FIG.  15 B  is a diagram of a top view of a second layer (Layer  2 )  280  of the printed circuit board having the filter  240 , according to embodiments of the present disclosure. The second layer  280  may be disposed below the first layer  270  (with respect to the z-axis  182 ). As illustrated, the second layer  280  may include the first stub  258  and the third connecting trace  260  that couples the first stub  258  to the first trace rod  256 . Similarly, the second layer  280  may also include the second stub  264  and the fourth connecting trace  266  that couples the second stub  264  to the second trace rod  262 . 
       FIG.  15 C  is a diagram of a top view of a third layer (Layer  3 )  290  of the printed circuit board having the filter  240 , according to embodiments of the present disclosure. The third layer  290  may be disposed below the second layer  280  (with respect to the z-axis  182 ). As illustrated, the third layer  290  may not include any components of the filter  240 , but may include a first hole  292  for the first trace rod  256  to pass through and a second hole  294  for the second trace rod  262  to pass through. 
       FIG.  15 D  is a diagram of a top view of a fourth layer (Layer  4 )  300  of the printed circuit board having the filter  240 , according to embodiments of the present disclosure. The fourth layer  300  may be disposed below the third layer  290  (with respect to the z-axis  182 ). As illustrated, the fourth layer  300  may include the main branch  246  coupled to the first circle trace  248  via the first connecting trace  250 , and coupled to the second circle trace  252  via the second connecting trace  254 . The fourth layer  300  may also include the first trace rod  256  coupled to the first circle trace  248 , and the second trace rod  262  coupled to the second circle trace  252 . 
       FIG.  15 E  is a diagram of a top view of a fifth layer (Layer  5 )  310  of the printed circuit board having the filter  240 , according to embodiments of the present disclosure. The fifth layer  310  may be disposed below the fourth layer  300  and be the bottom of the printed circuit board (with respect to the z-axis  182 ). As illustrated, the fifth layer  310  may not include any components of the filter  240 . 
       FIG.  15 F  is a diagram of a side view of the printed circuit board (PCB)  320  having the filter  240 , according to embodiments of the present disclosure. As illustrated and described above, the PCB  320  includes the first layer  270 , the second layer  280 , the third layer  290 , the fourth layer  300 , and the fifth layer  310 , though in additional or alternatively embodiments, the PCB  320  may include any suitable number (e.g., more or less) layers, such as three layers, four layer, more than five layers, and so on. Pre-preg may be disposed between the layers and serve as a dielectric. As further illustrated, the first trace rod  256  and the second trace rod  262  extend from the fourth layer  300  to the second layer  280 . Because the filter  240  may be disposed on intermediate or deeper layers (e.g., the second layer  280  and the fourth layer  300 ) of a printed circuit board (e.g.,  320 ), path loss may be decreased in wireless signals sent and/or received from the electronic device  10 , as discussed with respect to  FIG.  12    above. 
     The main branch  246 , the first and second circle traces  248 ,  252 , and the first and second stubs  258 ,  264  may act as lumped elements to enable the filter  240  to reject power of a wireless signal having an undesired frequency while causing a decreased power loss to a wireless signal having a desired frequency. In particular, the main branch  246  may act as the inductor L 1  ( 132 ), the first circle trace  248  and the first stub  258  as the first capacitor C 1  ( 134 ) coupled to a first end or node  136  of the inductor  132 , and the second circle trace  252  and the second stub  264  as the second capacitor C 2  ( 138 ) coupled to a second end or node  140  of the inductor  132 , as shown in the circuit diagram of the lumped-element approximation of  FIG.  6   . 
     In particular, the filter  240  may act as a band stop filter that rejects at least 3.5 dB of power of a wireless signal having a frequency of at least 36.4 GHz, while causing a power loss of at most 0.33 dB to a wireless signal having a frequency lower than 29.5 GHz.  FIG.  16    is a plot showing power loss  328  of the filter  240  with varying frequency, according to embodiments of the present disclosure. As illustrated, for frequencies lower than 29.5 GHz, the filter  240  causes a power loss  328  (e.g., an out-of-band loss) of at most 0.33 dB. For example, at 26.25 GHz, the filter  240  causes a power loss  328  of 0.18 dB, and at 29.5 GHz, the filter  240  causes a power loss  328  of 0.32 dB. At frequencies of at least 36.4 GHz, the filter  240  causes a power loss  328  (e.g., an in-band rejection) of greater than 3.5 dB. For example, at 36.4 GHz, the filter  240  causes a power loss  328  of 3.6 dB. The performance shown in the plot may be particularly suited for mmWave operation that may occur over a frequency range at less than or equal to 29.5 GHz and experience noise at 31 GHz or greater (e.g., at 32.3 GHz as may be caused by satellite and/or space communication). 
       FIG.  17    is a diagram of a band stop filter  330 , according to embodiments of the present disclosure. As with the filter  100  of  FIG.  5   , the band stop filter  330  may include a distributed-element filter rather than a lumped-element filter. The filter  330  may include a first terminal  332  (e.g., an input terminal) and a second terminal  334  (e.g., an output terminal). While the first terminal  332  may couple to an electrical current source and the second terminal  334  may provide an output current, in alternative embodiments, this may be reversed. 
     The filter  330  may also include a main (e.g., series) branch trace  336  coupling the first terminal  332  to the second terminal  334 . Varying dimensions of the main branch  336  may affect loss of a power of a signal passing through the filter  330  of a desired frequency (e.g., out-of-band loss) and rejection of a power of a signal to vary passing through the filter  330  of an undesired frequency (e.g., in-band rejection). In particular, increasing the length (e.g., along the x-axis  106 ) of the main branch  336  may increase the out-of-band loss, while increasing the in-band rejection, as discussed in further detail below. The main branch  336  may be approximately 1.1 mm long or less (e.g., 0.3 mm along the x-axis  106 ), and approximately 42 μm wide (e.g., along the y-axis  108 ), though the main branch  336  may be of any suitable dimensions that enable effective out-of-band loss and in-band rejection performance and/or coupling to other circuitry (e.g., greater than 0 μm long and greater than 0 μm wide, greater than 10 μm long and greater than 10 μm wide, greater than 100 μm long and greater than 50 μm wide, greater than 200 μm long and greater than 100 μm wide, greater than 500 μm long and greater than 300 μm wide, and so on), as discussed in further detail below. 
     As illustrated, the filter  330  includes a first parallel branch  338  coupled to and alongside or coextending with the main branch  336  via a first connecting trace  340 , and a second parallel branch  342  coupled to and alongside or coextending with the first parallel branch  338  via a second connecting trace  344 . As with the main branch  336 , varying dimensions of the first parallel branch  338  and/or the second parallel branch  342  may affect out-of-band loss and in-band rejection. In particular, increasing the length of the first parallel branch  338  and/or the second parallel branch  342  (e.g., along the x-axis  106 ) may increase the out-of-band loss, while increasing the in-band rejection, as discussed in further detail below. As illustrated, the first connecting trace  340  may couple to the main branch  336  at the first terminal  332 , and may be approximately orthogonal (e.g., 90°) to or intersect the main branch  336 , though, in additional or alternative embodiments, the first connecting trace  340  may couple the main branch  336  to the first parallel branch  338  at any suitable angle. Similarly, the second connecting trace  344  may couple to the first parallel branch  338  to the second parallel branch  342  at an approximately orthogonal angle (e.g., 90°), though, in additional or alternative embodiments, the second connecting trace  344  may couple the first parallel branch  338  to the second parallel branch  342  at any suitable angle. As illustrated, the second parallel branch  342  is coupled to an electrical ground  346 , providing a low impedance pathway for higher frequency signals (e.g., between 36.4 and 41.2 GHz), thus acting as a shunt. 
     In some embodiments, the first connecting trace  340  and/or the second connecting trace  344  may have similar dimensions as the first and/or second connecting trace  114 ,  118  of the filter  100  of  FIG.  5   . In particular, the first connecting trace  340  and the second connecting trace  344  may, together, have a total length (e.g., along the x-axis  106 ) of less than 6 mm (e.g., approximately 4 m), though any suitable total length is contemplated (e.g., 6 mm or greater, 10 mm or greater, 12 mm or greater, and so on). Moreover, the first connecting trace  340  may be greater in length (e.g., along the x-axis  106 ) than the second connecting trace  344 , though, in additional or alternative embodiments, their lengths may be approximately equal, or the length of the second connecting trace  344  may be greater than the length of the first connecting trace  340 . For example, the length of the first connecting trace  340  may be approximately 2.5 mm, and the length of the second connecting trace  344  may be approximately 1.5 mm. 
     As further illustrated, the first parallel branch  338  and/or the second parallel branch  342  may have similar dimensions as the first and/or second parallel branches  112 ,  117  of the filter  100  of  FIG.  5   . In particular, the first parallel branch  338  and the second parallel branch  342  may each have a length (e.g., along the x-axis  106 ) of less than 1.1 mm, though any suitable total length is contemplated (e.g., 1 mm or greater, 2 mm or greater, 5 mm or greater, 10 mm or greater, and so on). Moreover, the first parallel branch  338  may be shorter in length (e.g., along the x-axis  106 ) than the second parallel branch  342 , though, in additional or alternative embodiments, their lengths may be approximately equal, or the length of the second parallel branch  342  may be less than the length of the first parallel branch  338 . For example, the length of the first parallel branch  338  may be approximately 0.8 mm, and the length of the second parallel branch  342  may be approximately 1 mm. Additionally, the filter  330  may fit within a width  347  (e.g., along the y-axis  108 ) of 0.6 mm, though any suitable width is contemplated (e.g., 0.1 mm or greater, 0.3 mm or greater, 1 mm or greater, 5 mm or greater, and so on). 
     The main branch  336  and the first and second parallel branches  338 ,  342  may act as lumped elements to enable the filter  330  to reject power of a wireless signal having an undesired frequency while causing a decreased power loss to a wireless signal having a desired frequency.  FIG.  18    is a circuit diagram of a lumped-element approximation of the filter  330 , according to embodiments of the present disclosure. The illustrated circuit  360  approximates the main branch  336  as a series inductor  362  providing a series inductance L 1  and the first and second parallel branches  338 ,  342  as a shunt inductor  364  providing a shunt inductance L 2  coupled to a first end or node  366  of the series inductor  362 . The shunt inductor  364  is coupled to an electrical ground  368 , providing a low impedance pathway for higher frequency signals (e.g., between 36.4 and 41.2 GHz), thus acting as a shunt. 
     In particular, the filter  330  may act as a band stop filter that rejects at least 5.4 dB of power of a wireless signal having a frequency between 36.4 and 41.2 gigahertz, while causing a power loss of at most 0.34 dB to a wireless signal having a frequency lower than 29.5 GHz.  FIG.  19    is a plot showing power loss  380  of the filter  330  with varying frequency, according to embodiments of the present disclosure. As illustrated, for frequencies lower than 29.5 GHz, the filter  330  causes a power loss  380  (e.g., an out-of-band loss) of at most 0.34 dB. For example, at 26.5 GHz, the filter  330  causes a power loss  380  of 0.19 dB, and at 29.5 GHz, the filter  330  causes a power loss of 0.33 dB. At frequencies of between 36.4 and 41.2 GHz, the filter  330  causes a power loss  380  (e.g., an in-band rejection) of greater than 5.4 dB. For example, at 36.4 GHz, the filter  330  causes a power loss  380  of 5.9 dB, and at 41.3 GHz, the filter  330  causes a power loss  380  of 5.4 dB. The performance shown in the plot may be particularly suited for mmWave operation that may occur over a frequency range at less than or equal to 29.5 GHz and experience noise at 31 GHz or greater (e.g., at 32.3 GHz as may be caused by satellite and/or space communication). Because the filter  330  is made of distributed elements rather than lumped elements, the filter  330  may be disposed on an intermediate or deeper layer of a printed circuit board, such as the layer  202 C of the PCB  200  shown in  FIG.  12   , which may decrease path loss in wireless signals sent and/or received from the electronic device  10 , as discussed with respect to  FIG.  12    above. 
       FIG.  20    is a diagram of a band stop filter  390  with open shunt elements, according to embodiments of the present disclosure. As with the filter  100  of  FIG.  5   , the band stop filter  390  may include a distributed-element filter rather than a lumped-element filter. The filter  390  may include a first terminal  392  (e.g., an input terminal) and a second terminal  394  (e.g., an output terminal). While the first terminal  392  may couple to an electrical current source and the second terminal  394  may provide an output current, in alternative embodiments, this may be reversed. 
     The filter  390  may also include a main (e.g., series) branch trace  396  coupling the first terminal  392  to the second terminal  394 . Varying dimensions of the main branch  396  may affect loss of a power of a signal passing through the filter  390  of a desired frequency (e.g., out-of-band loss) and rejection of a power of a signal to vary passing through the filter  390  of an undesired frequency (e.g., in-band rejection). In particular, increasing the length (e.g., along the x-axis  106 ) of the main branch  396  may increase the out-of-band loss, while increasing the in-band rejection, as discussed in further detail below. As illustrated, the main branch  396  may be less than 1.1 mm long (e.g., along the x-axis  106 ), such as 1 mm, and approximately 42 μm wide (e.g., along the y-axis  108 ), though the main branch  396  may be of any suitable dimensions that enable effective out-of-band loss and in-band rejection performance and/or coupling to other circuitry (e.g., greater than 0 μm long and greater than 0 μm wide, greater than 10 μm long and greater than 10 μm wide, greater than 100 μm long and greater than 50 μm wide, greater than 200 μm long and greater than 100 μm wide, greater than 500 μm long and greater than 300 μm wide, and so on), as discussed in further detail below. 
     As illustrated, the filter  390  includes a first parallel branch or trace  398  coupled and parallel to, alongside, or coextensive with the main branch  396  via a first connecting trace  400 . As with the main branch  396 , varying dimensions of the first parallel branch  398  may affect out-of-band loss and in-band rejection. In particular, increasing the length (e.g., along the x-axis  106 ) of the first parallel branch  398  may increase the out-of-band loss, while increasing the in-band rejection, as discussed in further detail below. As illustrated, the first connecting trace  400  may couple to the main branch  396  at the first terminal  392 , and may be approximately orthogonal (e.g., 90°) to or intersect the main branch  396  and the first parallel branch  398 , though, in additional or alternative embodiments, the first connecting trace  400  may couple the main branch  396  to the first parallel branch  398  at any suitable angle (e.g., greater than 0°, greater than 30°, greater than 45°, greater than 60°, less than 120°, less than 135°, less than 150°, less than 180°, and so on). As such, the first parallel branch  398  may extend in a direction (e.g., a same direction as the main branch  396 ) from the first terminal  392  to the second terminal  394  (along the x-axis  106 ). The first connecting trace  400  may be less than or equal to approximately 0.3 mm long (e.g., along the y-axis  108 ) and approximately 42 μm wide (e.g., along the x-axis  106 ), though the first connecting trace  400  may be of any suitable dimensions that enable coupling the first parallel branch  398  to the main branch  396  (e.g., greater than 0 μm long and greater than 0 μm wide, greater than 10 μm long and greater than 10 μm wide, greater than 50 μm long and greater than 20 μm wide, greater than 100 μm long and greater than 50 μm wide, and so on). 
     As further illustrated, the first parallel branch  398  may have a length less than that of the main branch  396  (e.g., along the x-axis  106 ), such as 0.7 mm, and be approximately 42 μm wide (e.g., along the y-axis  108 ), though the first parallel branch  398  may be of any suitable dimensions that enable effective out-of-band loss and in-band rejection performance (e.g., greater than 0 μm long and greater than 0 μm wide, greater than 10 μm long and greater than 10 μm wide, greater than 100 μm long and greater than 50 μm wide, greater than 200 μm long and greater than 100 μm wide, greater than 500 μm long and greater than 300 μm wide, and so on), as discussed in further detail below. That is, the first parallel branch  398  may have a length less than a distance between the first terminal  392  and the second terminal  394 . Accordingly, while a first end of the first parallel branch  398  that couples to the first connecting trace  400  is aligned with the first terminal  392  (along the y-axis  108 ), a second end (or open stub) of the first parallel branch  398  may extend past the second terminal  394  (with respect to the y-axis  108 ). 
     Additionally, the filter  390  may include a second parallel branch or trace  402  coupled and parallel to, alongside, or coextensive with the main branch  396  via a second connecting trace  404 . In particular, the second connecting trace  404  may extend from the main branch  396  in an opposite direction (e.g., with respect to the y-axis  108  and/or the main branch  396 ) than the first connecting trace  400 . As with the main branch  396  and the first parallel branch  398 , varying dimensions of the second parallel branch  402  may affect out-of-band loss and in-band rejection. In particular, increasing the length (e.g., along the x-axis  106 ) of the second parallel branch  402  may increase the in-band loss, while increasing the in-band rejection, as discussed in further detail below. As illustrated, the second connecting trace  404  may couple to the main branch  396  at the second terminal  104 , and may be approximately orthogonal (e.g., 90°) to or intersect the main branch  396  and the second parallel branch  402 , though, in additional or alternative embodiments, the second connecting trace  404  may couple the main branch  396  to the second parallel branch  402  at any suitable angle (e.g., greater than 0°, greater than 30°, greater than 45°, greater than 60°, less than 120°, less than 135°, less than 150°, less than 180°, and so on). 
     The second connecting trace  404  may have similar dimensions as the first connecting trace  400 , and may extend in a direction from the second terminal  394  to the first terminal  392  (along the x-axis  106 ). The second parallel branch  402  may also have similar dimensions as the first parallel branch  398 , and thus may have a length less than that of the main branch  396 . That is, the second parallel branch  402  may have a length less than a distance between the first terminal  392  and the second terminal  394 . Accordingly, while a first end of the second parallel branch  402  that couples to the second connecting trace  404  is aligned with the second terminal  394  (along the y-axis  108 ), a second end (or open stub) of the second parallel branch  402  may extend past the first terminal  392  (with respect to the y-axis  108 ). Additionally, the filter  390  may fit within a width  405  (e.g., along the y-axis  108 ) of 0.7 mm, though any suitable width is contemplated (e.g., 0.1 mm or greater, 0.3 mm or greater, 0.5 mm or greater, 1 mm or greater, 5 mm or greater, and so on). 
     The main branch  396  and the first and second parallel branches  398 ,  402  may act as lumped elements to enable the filter  390  to reject power of a wireless signal having an undesired frequency while causing a decreased power loss to a wireless signal having a desired frequency. In particular, the main branch  396  may act as the inductor L 1  ( 132 ), the first parallel branch  398  as the first capacitor C 1  ( 134 ) coupled to a first end or node  136  of the inductor  132 , and the second parallel branch  402  as the second capacitor C 2  ( 138 ) coupled to a second end or node  140  of the inductor  132 , as shown in the circuit diagram of the lumped-element approximation of  FIG.  6   . Moreover, the first parallel branch  398  and the second parallel branch  402  may acts as open shunt elements, providing low impedance pathways for higher frequency signals (e.g., between 36.4 and 50 GHz). 
     The filter  390  may act as a band stop filter that rejects at least 5.3 dB of power of a wireless signal having a frequency between 36.4 and 50 GHz, while causing a power loss of at most 0.28 dB to a wireless signal having a frequency lower than 29.5 GHz.  FIG.  21    is a plot showing power loss  410  of the filter  390  with varying frequency, according to embodiments of the present disclosure. As illustrated, for frequencies lower than 29.5 GHz, the filter  390  causes a power loss  410  (e.g., an out-of-band loss) of at most 0.28 dB. For example, at 26.5 GHz, the filter  390  causes a power loss  410  of 0.19 dB, and at 29.5 GHz, the filter  100  causes a power loss of 0.28 dB. At frequencies between 36.4 and 50 GHz, the filter  390  causes a power loss  410  (e.g., an in-band rejection) of at least 5.3 dB. For example, at 36.4 GHz, the filter  390  causes a power loss  410  of 5.4 dB. The performance shown in the plot may be particularly suited for mmWave operation that may occur over a frequency range at less than or equal to 29.5 GHz (e.g., on the n257 band (26.5-29.5 GHz), the n258 band (24.25-27.5 GHz), the n261 band (27.5-28.35 GHz), and so on) and experience noise at 31 GHz or greater (e.g., at 32.3 GHz as may be caused by satellite and/or space communication). Because the filter  390  is made of distributed elements rather than lumped elements, the filter  390  may be disposed on an intermediate or deeper layer of a printed circuit board, such as the layer  202 C of the PCB  200  shown in  FIG.  12   , which may decrease path loss in wireless signals sent and/or received from the electronic device  10 , as discussed with respect to  FIG.  12    above. 
     Other dimensional characteristics of the filters described herein may affect filtering performance. For example, a distance between the main branch  396  and each parallel branch  398 ,  402  may affect out-of-band loss and in-band rejection.  FIG.  22    is a diagram of a band stop filter  420  with open shunt elements, according to embodiments of the present disclosure. The filter  420  may be similar, have similar components, and have similar dimensions to the band stop filter  390  of  FIG.  20   . Additionally, the first parallel branch  398  and the second parallel branch  402  of the filter  420  may be spaced from an electrical ground  422  (e.g., of a layer of a circuit board on which the filter  420  is disposed) by a buffer or ground gap  423  having a distance (e.g., along the y-axis  108 ) of approximately 0.12 mm (though any suitable distance  423  is contemplated). Moreover, while the second parallel branch  402  is shorter in length (along the x-axis  106 ) than the main branch  396 , the first parallel branch  398  may be approximately greater to or equal in length (along the x-axis  106 ) to the main branch  396 . That is, while a first end of the first parallel branch  398  that couples to the first connecting trace  400  is aligned with the first terminal  392  (along the y-axis  108 ) and a second end (or open stub) of the first parallel branch  398  is aligned with or may extend past the second terminal  394  (with respect to the y-axis  108 ), a first end of the second parallel branch  402  that couples to the second connecting trace  404  is aligned with the second terminal  394  (along the y-axis  108 ) and a second end (or open stub) of the second parallel branch  402  may not reach the first terminal  392  (with respect to the y-axis  108 ). 
     Further, a distance  425  between a distal edge  424  of the main trace  396  and a proximal edge  426  of each parallel branch  398 ,  402  (with respect to the y-axis  108 ) may be approximately 0.12 mm (though any suitable distance  425  is contemplated). In some embodiments, the main branch  396  may be less than a length  397  of an accommodating space  399  of 1.1 mm long (e.g., along the x-axis  106 ), such as 1 mm, and approximately 42 μm wide (e.g., along the y-axis  108 ), though the main branch  396  may be of any suitable dimensions that enable effective out-of-band loss and in-band rejection performance and/or coupling to other circuitry (e.g., greater than 0 μm long and greater than 0 μm wide, greater than 10 μm long and greater than 10 μm wide, greater than 100 μm long and greater than 50 μm wide, greater than 200 μm long and greater than 100 μm wide, greater than 500 μm long and greater than 300 μm wide, and so on), as discussed in further detail below. Additionally, the filter  420  may fit within a width  427  (e.g., along the y-axis  108 ) of 0.56 mm, though any suitable width is contemplated (e.g., 0.1 mm or greater, 0.3 mm or greater, 0.5 mm or greater, 1 mm or greater, 5 mm or greater, and so on). 
     As this distance (e.g., a distance between the main trace  396  and each parallel branch  398 ,  402 ) increases, the greater the out-of-band loss and in-band rejection.  FIG.  23    is a plot showing power loss  440  of the filter  420  with varying frequency, according to embodiments of the present disclosure. In particular, the power loss  440  corresponds to the distance between the main trace  396  and each parallel branch  398 ,  402  being 0.12 mm. As illustrated, with the distance being 0.12 mm, the filter  420  may cause a power loss  440  (e.g., an out-of-band loss) of 0.2 dB at 26.5 GHz, a power loss (e.g., an out-of-band loss)  440  of 0.25 dB at 30 GHz, and a power loss  440  (e.g., an in-band rejection) of 3.3 dB at 36.5 GHz. 
     Additionally, the power loss  442 ,  444 ,  446 , and  448  correspond to the distance being 0.14 mm, 0.16 mm, 0.18 mm, and 0.2 mm, respectively. Accordingly, the greater the distance between the main trace  396  and each parallel branch  398 ,  402 , the greater the power loss (e.g., the greater the out-of-band loss and in-band rejection), and vice versa. It should be understood that this relationship may be applied to any of the filters described above, such as the filter  100  of  FIG.  5   , the filter  390  of  FIG.  20   , and so on. However, increasing the distance between the main trace  396  and each parallel branch  398 ,  402  may result in increasing a width of a routing channel (e.g., the routing channel  210  of  FIG.  13   ) of a layer of a printed circuit board, which may take up more space in the electronic device  10 . 
     Another dimensional characteristic that may affect filtering performance is the ground gap between a filter and an electrical ground of a layer of a printed circuit board on which the filter is disposed (e.g., bordering a routing channel).  FIG.  24    is a diagram of a band stop filter  460  with open shunt elements, according to embodiments of the present disclosure. The filter  460  may be similar, have similar components, and have similar dimensions to the band stop filter  420  of  FIG.  22   . Additionally, a distance  425  between the distal edge  424  of the main trace  396  and a proximal edge  426  of each parallel branch  398 ,  402  (with respect to the y-axis  108 ) may be approximately 0.12 mm (though any suitable distance  425  is contemplated). In some embodiments, the main branch  396  may be less than a length  397  of an accommodating space  399  of 1.1 mm long (e.g., along the x-axis  106 ), such as 1 mm, and approximately 42 μm wide (e.g., along the y-axis  108 ), though the main branch  396  may be of any suitable dimensions that enable effective out-of-band loss and in-band rejection performance and/or coupling to other circuitry (e.g., greater than 0 μm long and greater than 0 μm wide, greater than 10 μm long and greater than 10 μm wide, greater than 100 μm long and greater than 50 μm wide, greater than 200 μm long and greater than 100 μm wide, greater than 500 μm long and greater than 300 μm wide, and so on), as discussed in further detail below. Additionally, the filter  460  may fit within a width  461  (e.g., along the y-axis  108 ) of 0.41 mm, though any suitable width is contemplated (e.g., 0.1 mm or greater, 0.3 mm or greater, 0.5 mm or greater, 1 mm or greater, 5 mm or greater, and so on). 
     Moreover, as illustrated, the first parallel branch  398  and the second parallel branch  402  of the filter  460  may be spaced from the electrical ground  422  by a buffer or ground gap  423  having a distance (e.g., along the y-axis  108 ) of approximately 0.04 mm. As the distance of the ground gap  423  increases, the less the out-of-band loss and in-band rejection.  FIG.  25    is a plot showing power loss  470  of the filter  460  with varying frequency, according to embodiments of the present disclosure. In particular, the power loss  470  corresponds to the distance of the ground gap  423  being 0.04 mm. As illustrated, with the distance of the ground gap  423  being 0.04 mm, the filter  460  may cause a power loss  470  (e.g., an out-of-band loss) of 0.22 dB at 26.5 GHz, a power loss (e.g., an out-of-band loss)  470  of 0.28 dB at 30 GHz, and a power loss  470  (e.g., an in-band rejection) of 4.3 dB at 36.5 GHz. Additionally, the power loss  472 ,  474 , and  476  correspond to the distance of the ground gap  423  being 0.06 mm, 0.08 mm, and 0.12 mm, respectively. Accordingly, the greater the distance of the ground gap  423 , the less the power loss (e.g., the less the out-of-band loss and in-band rejection), and vice versa. It should be understood that this relationship may be applied to any of the filters described above, such as the filter  100  of  FIG.  5   , the filter  390  of  FIG.  20   , and so on. 
     The specific embodiments described above have been shown by way of example, and it should be understood that these embodiments may be susceptible to various modifications and alternative forms. It should be further understood that the claims are not intended to be limited to the particular forms disclosed, but rather to cover all modifications, equivalents, and alternatives falling within the spirit and scope of this disclosure. 
     The techniques presented and claimed herein are referenced and applied to material objects and concrete examples of a practical nature that demonstrably improve the present technical field and, as such, are not abstract, intangible or purely theoretical. Further, if any claims appended to the end of this specification contain one or more elements designated as “means for [perform]ing [a function] . . . ” or “step for [perform]ing [a function] . . . ,” it is intended that such elements are to be interpreted under 35 U.S.C. 112(f). However, for any claims containing elements designated in any other manner, it is intended that such elements are not to be interpreted under 35 U.S.C. 112(f). 
     It is well understood that the use of personally identifiable information should follow privacy policies and practices that are generally recognized as meeting or exceeding industry or governmental requirements for maintaining the privacy of users. In particular, personally identifiable information data should be managed and handled so as to minimize risks of unintentional or unauthorized access or use, and the nature of authorized use should be clearly indicated to users.

Metadata:
Filing Date: 20210825
Publication Date: 20240611
Grant Date: 20240611
Priority Date: 20210825
Inventors: MU, Xiaofang
ZHANG, BO
ZHU, MINGJUAN
Pham, Chi V.
CETINONERI, Berke
OGILVIE, TIMOTHY B.
Assignee: APPLE INC
CPC Classifications: [{"code": "H04B1/0057", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B1/52", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B2001/0408", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04B1/0057", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B1/52", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B2001/0408", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04B1/0483", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04B1/0483", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04B1/0483", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04B1/0057", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B1/52", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B2001/0408", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 85286685