FRONT END MODULE AND WIRELESS DEVICE HAVING NO POST AMPLIFIER BANDPASS FILTER
20230223965 · 2023-07-13
Inventors
Cpc classification
International classification
Abstract
According to the present disclosure there is provided a front end module comprising a bandpass filter, an antenna port for connection to an antenna and forming a signal path with the bandpass filter, and one or more amplifiers. The one or more amplifiers are disposed between the bandpass filter and the antenna port in the signal path. A corresponding wireless device and wireless access point are also provided.
Claims
1. A front end module comprising: a bandpass filter; an antenna port for connection to an antenna and forming a signal path with the bandpass filter; and one or more amplifiers, the one or more amplifiers being disposed between the bandpass filter and the antenna port in the signal path.
2. The front end module of claim 1 wherein the one or more amplifiers comprises: a first amplifier disposed between the antenna port and the bandpass filter in the signal path; and a second amplifier disposed between the antenna port and the bandpass filter in the signal path, wherein the front end module further comprises one or more switches arranged such that the front end module can be configured in either a transmit path configuration by selecting the first amplifier or a receive path configuration by selecting the second amplifier.
3. The front end module of claim 2 wherein the one or more switches comprises: a first switch disposed between the antenna port and the one or more amplifiers in the signal path; and a second switch disposed between the bandpass filter and the one or more amplifiers in the signal path, the first switch and the second switch allowing the front end module to be configured in either the transmit path configuration by selecting the first amplifier or the receive path configuration by selecting the second amplifier.
4. The front end module of claim 2 wherein the first amplifier comprises a power amplifier.
5. The front end module of claim 2 wherein the second amplifier comprises a low noise amplifier.
6. The front end module of claim 1 wherein the bandpass filter is in a small signal side of the power amplifier in the front end module.
7. The front end module of claim 1 wherein the bandpass filter is configured for use with Wi-Fi signals.
8. The front end module of claim 1 wherein the bandpass filter is a 5 GHz bandpass filter or a 6 GHz bandpass filter.
9. A wireless device comprising: one more antennae; and one or more front end modules, each front end module having a bandpass filter, an antenna port connected to one of the one or more antennae and forming a signal path with the bandpass filter, and one or more amplifiers, the one or more amplifiers being disposed between the bandpass filter and the antenna in the signal path.
10. The wireless device of claim 9 wherein the one or more amplifiers of each of the one or more front end modules comprises: a first amplifier disposed between the antenna port and the bandpass filter of the front end module in the signal path; and a second amplifier disposed between the antenna port and the bandpass filter of the front end module in the signal path, wherein each of the one or more front end modules further comprises one or more switches arranged such that the front end module can be configured in either a transmit path configuration by selecting the first amplifier or a receive path configuration by selecting the second amplifier.
11. The wireless device of claim 10 wherein the one or more switches of each of the one or more front end modules comprises: a first switch disposed between the antenna port and the one or more amplifiers of the front end module in the signal path; and a second switch disposed between the bandpass filter and the one or more amplifiers of the front end module in the signal path, the first switch and the second switch allowing the front end module to be configured in either the transmit path configuration by selecting the first amplifier or the receive path configuration by selecting the second amplifier.
12. The wireless device of claim 10 wherein the first amplifier of each of the one or more front end modules comprises a power amplifier.
13. The wireless device of claim 10 wherein the second amplifier of each of the one or more front end modules comprises a low noise amplifier.
14. The wireless device of claim 9 wherein the one or more front end modules comprises one or more pairs of front end modules and wherein, for each pair of front end modules, the bandpass filter of one front end module passes a different frequency range to the bandpass filter of the other front end module, such that the passbands of the bandpass filters do not overlap.
15. The wireless device of claim 14 wherein, for each pair of front end modules, the bandpass filter of one front end module is a 5 GHz bandpass filter the bandpass filter of the other front end module is a 6 GHz bandpass filter.
16. The wireless device of claim 9 wherein the one or more front end modules comprises two or more pairs of front end modules and wherein the bandpass filters of one pair of front end modules are configured for use in a different geographical region to the bandpass filters of another pair of front end modules.
17. The wireless device of claim 16 further comprising a region detector configured to detect a geographical region in which the wireless device is located and to automatically configure the wireless device for that geographical region by selecting a pair of front end modules configured for use in the detected geographical region for use in a transmit path configuration of the wireless device and a receive path configuration of the wireless device.
18. The wireless device of claim 9 wherein the one or more antennae comprises two or more antennae, at least two of the two or more antennae being different types of antenna or having different polarizations.
19. The wireless device of claim 9 wherein the one or more antennae comprises two or more antennae, at least two of the two or more antennae having least 20 dB of isolation between them.
20. The wireless device of claim 9 wherein the wireless device is a wireless mobile device or a wireless access point.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0061] Various aspects of at least one embodiment are discussed below with reference to the accompanying figures, which are not intended to be drawn to scale. The figures are included to provide illustration and a further understanding of the various aspects and embodiments, and are incorporated in and constitute a part of this specification, but are not intended as a definition of the limits of the invention. In the figures, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral. For purposes of clarity, not every component may be labeled in every figure. In the figures:
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DETAILED DESCRIPTION
[0073] Aspects and embodiments described herein are directed to a front end module, wireless device and wireless access point having no post amplifier bandpass filter, providing a more flexible and efficient device for transmitting and receiving wireless signals.
[0074] It is to be appreciated that embodiments of the methods and apparatuses discussed herein are not limited in application to the details of construction and the arrangement of components set forth in the following description or illustrated in the accompanying drawings. The methods and apparatuses are capable of implementation in other embodiments and of being practiced or of being carried out in various ways. Examples of specific implementations are provided herein for illustrative purposes only and are not intended to be limiting. Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use herein of “including,” “comprising,” “having,” “containing,” “involving,” and variations thereof is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. References to “or” may be construed as inclusive so that any terms described using “or” may indicate any of a single, more than one, and all of the described terms.
[0075]
[0076] When incorporated into an electronic device, the front end module 100 typically will be connected to a transceiver as part of a transmit path, a receive path, or both. The front end module 100 illustrated can be incorporated as part of both the transmit path and the receive path by virtue of amplifiers 103a, 103b and switch 107. Amplifiers 103a, 103b include a power amplifier 103a for use in the transmit path and a low noise amplifier 103b for use in the receive path, whilst switch 107 allows either to be connected into a signal path incorporating the bandpass filter 105 and the antenna 101. In
[0077] The bandpass filter 105, in this case a 5 GHz bandpass filter, only passes signals within its passband. That is, signals that are outside the passband of the bandpass filter 105 (out of band or 00B signals) are attenuated, typically by 50-60 dB, such that they are filtered out and are not passed down the signal path. One situation in which this is useful is when two or more antennae are used in proximity to each other, either on the same device or on another nearby device, to filter out unwanted incoming signals in a different band and to prevent transmitted signals from one antenna blocking the nearby antenna.
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[0080] However, bandpass filters, such as bandpass filters 105, 105′, typically have losses of around 3 dB. As this loss is after the power amplifier 103a, 103a′ in the transmit path this means that transmit power is reduced, reducing the effective range of the transmitter. Alternatively, more power is required to get an equivalent range when compared to a transmitter without a bandpass filter 105, 105′. Furthermore, placing a bandpass filter 105, 105′ after a power amplifier 103a, 103a′ can also degrade the performance of the power amplifier because of a poor match between the power amplifier 103a, 103a′ and the impedance of the bandpass filter 105, 105′ across the passband. It is difficult to design a wideband filter that has the desired impedance for operation with the power amplifier 103a, 103a′, typically 50Ω, across the entire passband. If the bandpass filter 105, 105′ presents a poor match to the power amplifier 103a, 103a′, the linearity of the amplifier can be degraded. With respect to the bandpass filter 105, 105′ in the receive path, because these are prior to the low noise amplifier 103b, 103b′, these bandpass filters 105, 105′ degrade the noise figure, reducing the range at which a receiver can successfully receive a signal.
[0081] Some or all of these problems, however, can be overcome by changing the placement of the bandpass filter.
[0082] Similarly to the front end modules of access point 200 illustrated in
[0083] With regards to the transmit path configuration that front end module 400′ is shown in, placing the bandpass filter 405′ before the power amplifier 403a′ reduces the losses in the signal path after the power amplifier 403a′ (i.e., it reduces the losses in the signal that is going to be transmitted from the antenna 401′). Furthermore, by placing the bandpass filter 405′ in the signal path prior to the amplification, smaller bandpass filters can be used that are less lossy, and the bandpass filters themselves will degrade less due to the smaller signals being handled. The bandpass filter 405′ reduces the amount of noise prior to amplification, and so still helps prevent the transmission of out of band noise. Front end module 400 is shown in the receive configuration. On the receive side, placing the bandpass filter 405 after the low noise amplifier 403b reduces losses in the signal path before the low noise amplifier 403b, reducing the effect of noise on the small, received signal. The bandpass filter 405 protects the filters on a system on a chip to which the front end module 400 is connected (e.g., a transceiver module) from out of band signals amplified by the low noise amplifier 403b. Preferably, the bandpass filters 405, 405′ have non-overlapping passbands to aid simultaneous transmission and receiving by being able to fully filter out signals in the band of the other.
[0084] Nevertheless, it will be appreciated that by removing the bandpass filter after the power amplifier 403a, 403a′, out of band noise generated by the power amplifier 403a, 403a′ is no longer attenuated by the filter 405, 405′. Any out of band noise that couples from the transmitter in one band (e.g., from 401′) to the receiver in the other band (e.g., to 401) will degrade the receiver's performance. By removing the bandpass filter from in front of the low noise amplifier 403b, 403b′, the low noise amplifier 403b, 403b′ will be subjected to large out of band blockers signals. The transmit signal from one band (e.g., from 401′) will couple to the low noise amplifier input and can degrade the linearity of the low noise amplifier. These potential issues can be addressed with a number of measures.
[0085] The transmit power of the power amplifier can be reduced, without reducing its saturated output power, moving it further away from its saturated output power. By doing this, the out of band noise produced by the power amplifier is significantly reduced. Operating at a lower transmit power will reduce the transmit range, but this can at least partially be compensated for by the reduction in post power amplification losses due to the removal of the post power amplifier bandpass filter.
[0086] The antenna isolation can be improved. With careful antenna design, antenna isolation of 40 dB or more can be achieved. This improves both transmit path out of band noise (since less out of band power is coupled into the victim receiver) and receive path saturation (since less transmit power is coupled to the receiver). Antennae can be isolated using a number of measures, such as by increasing their physical spacing, using different polarizations for different antennae, using different types of antennae, or any other techniques known in the art.
[0087] The linearity of the receivers can be improved by increasing the low noise amplifier's input third order intercept point (IIP3). Providing a large, more linear region of operation for the receive path low noise amplifiers helps to counteract the fact that they are amplifier out of band signals received prior to the out of band signals being filtered out by the bandpass filter on the receive path.
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[0089] The simulations were performed with the following parameters and assumptions: [0090] The access point has 40 dB antenna isolation between the 5 and 6 GHz chains; [0091] The power amplifier has a saturation power, P.sub.sat, of 30 dBm; [0092] The access point uses 4 transmit streams; [0093] The transmit signal is 160 MHz in the 6 GHz channel on channel 15 (6,025 MHz) and the receive signal is 20 MHz in the 5 GHz channel 177 (5,885 MHz); [0094] Post power amplifier losses are 1 dB with the bandpass filter between system on a chip and the front end module (i.e., no post amplifier bandpass filter), and 4 dB with the bandpass filter placed between the amplifiers and the antenna; [0095] The bandpass filter is a bulk acoustic wave (BAW) filter having 30 dB rejection at 50 MHz offset and 3 dB loss; [0096] The access point low noise amplifier has IIP3=+8 dBm; and [0097] The mobile station transmits data to the access point at a power of 16 dBm with an error vector magnitude (EVM) of −50 dB.
[0098] The different figures,
[0099] Looking first at
[0100] At 15 dBm transmit power, the transmit range is 4.1 m and the receive range is 5.4 m. As the transmit power is increased, the MCS13 receive range decreases due to increased out of band noise from the transmit path power amplifier that is incorporated into the transmission from the transmission antenna and is received at the receiving antenna and which degrades the linearity of the receiver low noise amplifier. With the parameters and assumptions described above, MCS13 cannot be received for transmit powers exceeding 20 dBm due to excessive out of band noise. The transmit range increases as power increases until 19 dBm, at which point the power amplifier linearity starts to degrade. By 21 dBm, the power amplifier's EVM is no longer able to support MCS13 operation.
[0101] The bottom chart shows transmit power rate vs range when the bandpass filter is placed after the power amplifier. The transmit range is 4.1 m at 15 dBm. Beyond 16 dBm, the transmit range degrades quickly because the power amplifier's linearity has degraded due to the additional post power amplifier losses of the bandpass filter. The receive range remains constant at 5.6 m, regardless of transmit power. This is expected since the bandpass filter will reject all noise from the receive path (before the received signal is processed or amplified at all), making the receiver independent of transmit power (as all received transmit signal is rejected). Note that the receive range of 5.6 m for this solution (for all transmit powers) is comparable to the range seen when the filter is placed between the system on a chip and the front end module (top graph). This occurs because the noise figure is improved by moving the filter to be placed after the low noise amplifier, and this compensates for the degradation due to the out of band noise.
[0102] As can be seen by comparing the top and bottom graphs of
[0103] Turning to
[0104] A front end module having the bandpass filter on the small signal side of the power amplifier rather than after the power amplifier can be implemented in a number of different ways, depending upon various considerations such as manufacturing ease, existing module designs, flexibility of module design, and the like.
[0105] Front end modules 900, 900′ differ, however, in that front end module 900′ comprises a single integrated front end module sub-unit 905 whereas front end module 900 comprises a bandpass filter front end module sub-unit 901 and an amplifier front end module sub-unit 903. Making a front end module 900′ comprising a single integrated front end module sub-unit 905, having the bandpass filter 405 and the amplifiers 403 therein, may mean that the front end module 900′ can be made more efficient and compact. However, separate front end modules 900′ would then be utilized for operation in different bands, for example, at 5 GHz and at 6 GHz, potentially increasing manufacturing costs and reducing the flexibility of the front end module 900′. On the other hand, having a front end module 900 with a separate bandpass filter front end module sub-unit 901 and amplifier front end module sub-unit 903 allows the flexibility of the front end module 900 to be increased. This is because the band in which the front end module 900 is configured to operate can easily be changed by switching the bandpass filter front end module sub-unit 901 to one with a bandpass filter having a different passband, without needing to change the amplifier front end module sub-unit 903. Similarly, manufacturing may be simplified as the same amplifier front end module sub-unit 903 may be used across front end modules 900 having different passbands. However, the front end module 900 may be less compact and less efficient by having a separate bandpass filter front end module sub-unit 901 and amplifier front end module sub-unit 903.
[0106] While the front end modules of
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[0108] In the dual band architecture of
[0109] Two such identical front end modules 1000 can be incorporated into a wireless device to allow for simultaneous transmission and receiving in the two bands covered by the bandpass filters 1005a, 1005b. In this case, it is preferable that the bandpass filters 1005a, 1005b have non-overlapping passbands.
[0110] Whilst
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[0112] As shown in
[0113] Aspects and embodiments of front end modules as described herein may be incorporated into the wireless device 1100 of
[0114] It will be appreciated that the front end modules described herein, and, for example, used in wireless device 1100, can be arranged in a number of ways for different applications. For example, four 5 GHz front end modules and four 6 GHz front end modules (i.e., four pairs of front end modules 400, 400′ illustrated in
[0115] The front end modules described herein may be configured to operate with different types of wireless communication, including but not limited to Wi-Fi (including Wi-Fi 7), LTE, 4G, 5G, and 6G.
[0116] Having described above several aspects of at least one embodiment, it is to be appreciated various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be part of this disclosure and are intended to be within the scope of the present disclosure. Accordingly, the foregoing description and drawings are by way of example only, and the scope of the invention should be determined from proper construction of the appended claims, and their equivalents.