Patent Description:
In general, higher frequency bands have more bandwidth available for wireless communications and as the demand for wireless communications increases, it has become desirable to exploit millimeter-waves for such communications. Consequently, current standardization efforts in the field of wireless communications consider the use of millimeter-waves. For example, 3rd Generation Partnership Project, 3GPP, develops <NUM> technology, which may be referred to as New Radio, NR, radio access technology as well, and considers the use of millimeter-wave frequency bands at least for <NUM>/NR.

However, the use of millimeter-waves for communication also brings additional challenges because a millimeter-wave signal typically experiences higher losses compared to a lower frequency signal. There is therefore a need to provide an apparatus which efficiently amplifies a power of a signal for an antenna. Similar enhancements may also be employed in other cellular networks and in several other wireless communication networks as well, such as, for example, in Wireless Local Area Networks, WLANs. <CIT> discloses an RF power amplifier feeding a symmetric antenna.

According to some aspects, there is provided the subject-matter of the independent claim <NUM>. Some embodiments are defined in the dependent claims.

According to claim <NUM>, there is provided an apparatus for an antenna, comprising, a first power amplifier and a second power amplifier and a common ground between the first power amplifier and the second power amplifier, wherein a Radio Frequency, RF, output of the first power amplifier is coupled to the common ground and a RF output of the second power amplifier is coupled to the common ground.

According to an aspect of the present invention, the first and the second power amplifiers may be coupled to the common ground.

According to claim <NUM>, the RF output of the first power amplifier may be shifted <NUM> degrees compared to the RF output of the second power amplifier.

According to an aspect of the present invention, return current may flow in the common ground.

According to claim <NUM>, the RF output of the first power amplifier and the RF output of the second power amplifier is configured to form a balanced feed for the antenna.

According to an aspect of the present invention, the apparatus may be coupled to, or comprise, a dipole antenna.

According to an aspect of the present invention, the apparatus may be coupled to, or comprise, a patch antenna.

According to an aspect of the present invention, the apparatus may be coupled to, or comprise, a multi-layer planar antenna.

According to an aspect of the present invention, the first and the second power amplifiers may be two-way power amplifiers.

According to an aspect of the present invention, the first and the second power amplifiers may be integrated in a Monolithic Microwave Integrated Circuit, MMIC.

A wireless network node may comprise the apparatus according to any of the aspects of the present invention. Moreover, the wireless network node may be a base station configured to operate in accordance with a 3rd Generation Partnership Project, 3GPP, standard. In some embodiments, the 3GPP standard may be a <NUM> standard.

A wireless terminal may comprise the apparatus according to any of the aspects of the present invention as well.

Embodiments of the present invention relate to a power amplifier for an antenna. More specifically, embodiments of the present invention provide an efficient power amplifier which can be used to reduce losses when amplifying a Radio Frequency, RF, signal. In some embodiments, the power amplifier may comprise a first and a second power amplifier, and a common ground between the first power amplifier and the second power amplifier, thereby generating a balanced feed while enabling less loss. Thus, the common ground may be common for the first power amplifier and the second power amplifier, i.e., the first power amplifier and the second power amplifier may be coupled to the common ground.

Embodiments of the present invention may be used, e.g., for amplifying millimeter-wave signals. Demand for additional frequency spectrum is constantly increasing and hence it is desirable to use higher, millimetre-wave frequencies for wireless communications. Especially on high frequencies losses may be an issue but in general embodiments of the present invention may be used for amplifying any signal, regardless of the frequency.

Millimeter-wave frequencies are considered, e.g., in the context of <NUM>, i.e., New Radio, NR, networks and for future cellular networks as well. Embodiments of the invention are not limited to cellular networks though, and can be exploited in any system that uses a power amplifier. Millimetre-wave frequencies can be used for all kinds of transmissions between wireless devices, including radio access and backhaul connections.

For instance, a wireless communication network may comprise one or more wireless terminals, base stations, relay nodes and/or core network elements. A wireless terminal may be connected to a base station and/or relay node via air interface. Then, wireless communications may be performed over the air interface using a Radio Access Technology, RAT. In case of cellular networks, the RAT may be for example Long Term Evolution, LTE, New Radio, NR, or MulteFire. In case of non-cellular networks, the RAT may be for example Wireless Local Area Network, WLAN.

Using NR as an example of a cellular RAT, a base station may be referred to as gNB and a wireless terminal may be referred to as a User Equipment, UE. In case of WLAN, a base station may be referred to as an access point. Generally speaking, a base station, a relay node and an access point may be referred to as wireless network nodes. In any case, embodiments are not restricted to any particular wireless technology. Instead, embodiments may be exploited in any wireless communication network, wherein a power amplifier is used for an antenna.

Concerning power amplifiers, <FIG> illustrates a fully differential antenna in accordance with at least some embodiments of the present invention. The fully differential antenna of <FIG> may comprise a RF input <NUM> and a power amplifier <NUM> coupled to the RF input <NUM>. In <FIG>, a fully differential current flow is denoted by <NUM>. Moreover, the fully differential antenna of <FIG> may also comprise an antenna <NUM>, such as a dipole antenna.

For instance, a fully differential power amplifier may be used for a fully differential antenna of <FIG>. In such a case, power may be combined within the fully differential antenna. Thus, on-chip, or Printed Circuit Board, PCB, power combining (or dividing) may be avoided, thereby achieving less loss. Nevertheless, differential output may be difficult to achieve especially if more power is required from the fully differential power amplifier.

Considering power amplifier designs, power is typically combined on-chip and the output is single-ended. However, power combining introduces losses. Another solution is to use a differential design, with a differential output, to drive a differential antenna, such as, for example, a dipole antenna. Such a solution may be used to avoid on-chip (or off-chip) power combining by combining power within the antenna, which reduces losses. Nevertheless, it is challenging, if not even impossible, to achieve a fully differential output with such a solution, especially if more power is required from the power amplifier.

Embodiments of the present invention therefore provide a power amplifier with a balanced output, i.e., a balanced feed to an antenna. Said balanced output may be exploited to achieve less loss. Moreover, balanced output may be easy to implement compared to other solutions. In general, balanced current flow may refer to a situation, wherein return current flows in common ground.

For example, some embodiments of the present invention may be exploited to improve an output power of millimeter-wave transmitters by using a balanced Monolithic Microwave Integrated Circuit, MMIC, a power amplifier and a planar antenna power combiner. Consequently, less loss may be achieved compared to a single-ended power amplifier and a patch, or a dipole antenna, configuration. Also, in accordance with at least some embodiments of the present invention, less loss compared to a fully differential power amplifier and antenna configuration may be achieved.

<FIG> illustrates an exemplary apparatus in accordance with at least some embodiments of the present invention. The apparatus <NUM> may be a power amplifier for an antenna, e.g., for a balanced dipole antenna. In some embodiments, an antenna may comprise the apparatus. Moreover, in some embodiments, a wireless terminal, a wireless network node or a relay node may comprise the apparatus <NUM>, and possibly the antenna as well.

The apparatus <NUM> of <FIG> may comprise a Radio Frequency, RF, input <NUM>, a first power amplifier <NUM> coupled to the RF input <NUM> and a second power amplifier <NUM> coupled to the RF input <NUM>. Moreover, in the apparatus <NUM>, a common ground <NUM> may be coupled to the first power amplifier <NUM> and the common ground <NUM> may also be coupled to the second power amplifier <NUM>.

As shown in <FIG>, the apparatus <NUM> may also comprise a RF output <NUM> of the first power amplifier <NUM> and a RF output <NUM> of the second power amplifier <NUM>. In some embodiments, the RF outputs <NUM> and <NUM> may be coupled to the common ground <NUM>. Thus, return current may flow in the common ground <NUM> in accordance with at least some embodiments. Alternatively, or in addition, the RF output <NUM> the first power amplifier <NUM> may be shifted <NUM> degrees compared to the RF output <NUM> of the second power amplifier <NUM>. In some embodiments, the shifting may take place at an input of the first power amplifier <NUM> or at an input of the second power amplifier <NUM>.

In some embodiments, the RF output <NUM> of the first power amplifier <NUM> and the RF output <NUM> of the second power amplifier <NUM> may form a balanced feed for an antenna. That is to say, the RF output <NUM> of the first power amplifier <NUM> and the RF output <NUM> of the second power amplifier <NUM> may be combined and fed to an antenna. The exemplary power amplifier may be coupled to the antenna via the RF output <NUM> of the first power amplifier <NUM> and the RF output <NUM> of the second power amplifier <NUM>. In some embodiments, the antenna may be a balanced dipole antenna, a patch antenna or a multi-layer planar antenna.

In some embodiments, the first power amplifier <NUM> and the second power amplifier <NUM> may be two-way power amplifiers. Alternatively, or in addition, the first power amplifier and the second power amplifier may be integrated in a MMIC.

<FIG> illustrates a balanced current flow in accordance with at least some embodiments of the present invention. In <FIG>, a common ground is denoted by <NUM>. The common ground <NUM> may correspond to the common ground <NUM> of <FIG>. Also, in <FIG> a feeding current flow is denoted by <NUM> and a return current flow is denoted by <NUM>.

In some embodiments, the apparatus <NUM> may be utilized for generating a balanced feed, e.g., for a multilayer planar antenna. For instance, in case of a balanced patch, different sides of the balanced patch may be excited using two apertures in the common ground plane <NUM>, <NUM>. Moreover, there may be a phase difference of <NUM> degrees between excitations, i.e., the apertures, and the common ground plane <NUM>, <NUM> between the excitations, thereby creating the balanced feed for an antenna. Alternatively, said balanced feed may be integrated to a dipole antenna. For example, whole E-band (<NUM> - <NUM>) may be covered with a balanced dipole antenna.

A balanced feed may be a supplementary feed mechanism to a single feed. When comparing the balanced feed to a single feed, the balanced feed enables smaller coupling apertures in the common ground. Consequently, back-radiation may be reduced. In general, the common ground may refer to a common ground plane in accordance with embodiments of the present invention.

While the forgoing examples are illustrative of the principles of the present invention in one or more particular applications, it will be apparent to those of ordinary skill in the art that numerous modifications in form, usage and details of implementation can be made without the exercise of inventive faculty.

At least some embodiments of the present invention find industrial application in wireless communication systems. Examples of wireless communication networks comprise <NUM>/NR and WLAN networks. For example, an apparatus in accordance with at least some embodiments of the present invention suits particularly well for wireless communication networks operating at millimetre-wave frequencies.

Claim 1:
An apparatus (<NUM>) for an antenna, comprising:
a first power amplifier (<NUM>) and a second power amplifier (<NUM>) connectable to the antenna; and
a common ground (<NUM>) between the first power amplifier (<NUM>) and the second power amplifier (<NUM>), wherein a Radio Frequency, RF, output of the first power amplifier (<NUM>) is coupled to the common ground (<NUM>) and an RF output of the second power amplifier (<NUM>) is coupled to the common ground (<NUM>), wherein the RF output of the first power amplifier (<NUM>) and the RF output of the second power amplifier (<NUM>) are configured to be coupled to the antenna and to form a balanced feed for the antenna, and the RF output of the first power amplifier (<NUM>) is shifted <NUM> degrees compared to the RF output of the second power amplifier (<NUM>).