TRANSCEIVERS

BACKGROUND

[0001] Within power amplifier low-noise amplifier (PALNA) applications the power handling capability of a transistor switch can be increased by stacking more devices in series in shunt operation or increasing the periphery in series operation. However both of these options either increase the losses or decrease the isolation of the switch network. Additionally, especially at millimeter-wave frequencies, series switch devices add loss to the signal path in on-state and suffer from capacitive feedthrough in the off state thus decreasing isolation. Therefore, shunt switches are typically utilized at millimeter- wave frequencies. However, current millimeter- wave switches suffer from poor linearity. Currently switch networks are limiting the linearity of millimeter- wave integrated (MMIC) PALNA systems.

SUMMARY OF THE INVENTION

[0002] Compared to transformer based switch presented in Finnish Patent Application 20185060, incorporated herein by reference, the differential transmission line based switch according to at least some embodiments of the present invention provides for a wider bandwidth while maintaining similar performance. Certain embodiments of the present invention provide for transmission lines with a reduced size by employing slow- wave design techniques.

[0003] The invention is defined by the features of the independent claims. Some specific embodiments are defined in the dependent claims.

[0004] According to a first aspect of the present invention, there is provided a differential transmission line based switch configured to be connected to a power amplifier (PA) and/or Low Noise Amplifier (LNA), said transmission line based switch comprising: a first input port conductively connected to: an input of a first transmission line of a first circuit and an input of a first transmission line of a second circuit; a second input port conductively connected to an input of a second transmission line of the first circuit; a first switch of the first circuit conductively connected at one end to an output of the first transmission line of the first circuit, the other end of the first switch of the first circuit being configured to be connected to a ground potential; a first switch of the second circuit conductively connected at one end to an output of the first transmission line of the second circuit, the other end of the first switch of the second circuit being configured to be connected to a ground potential; a second switch of the first circuit conductively connected at one end to an output of the transmission line of the first circuit, the other end of the second switch of the first circuit being configured to be connected to a ground potential; first and second output ports of the first circuit, the first output port being conductively connected to the output of the first transmission line of the first circuit, the second output port being conductively connected to the output of the second transmission line of the first circuit; and a first output port of the second circuit conductively connected to the output of the first transmission line of the second circuit.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] FIGURE 1 illustrates a transmission line based switch in accordance with at least some embodiments of the present invention;

[0006] FIGURE 2 illustrates a differential transmission line based switch according to certain embodiments of the present invention;

[0007] FIGURE 3 shows an embodiment of the present invention implementing a Monolithic Microwave Integrated Circuit (MMIC);

[000S] FIGURE 4 illustrates a transmission line based switch incorporating slow- wave transmission lines and common mode chokes according to at least some embodiments of the present invention; [0009] FIGURE 5 shows a transmission line based switch having common mode chokes which are implemented with transmission lines in accordance with certain embodiments of the present invention; and

[0010] FIGURE 6 illustrates the embodiments of FIGURE 5 wherein the transmission lines are now slow-wave transmission lines.

EMBODIMENTS

[0011] At least some embodiments of the present invention provide for a transmission line based switch having a much greater linearity than traditional transistor based switches. Especially in the case of PALNA applications. Transmission line based switches according to the present invention also provide for lower insertion losses and power consumption while largely maintaining bandwidth.

[0012] FIGURE 1 illustrates a differential transmission line based switch 100 configured to be connected to a power amplifier (PA) 190 and/or Low Noise Amplifier (LNA) 191 in accordance with at least some embodiments of the present invention. As can be seen the differential transmission line based switch 100 comprises a first input port 131 conductively connected to: an input of a first transmission line 111 of a first circuit 101 and an input of a first transmission line 112 of a second circuit 102. A second input port 132 of the transmission line based switch 100 is conductively connected to an input of a second transmission line 113 of the first circuit 101. There is a first switch 121 of the first circuit 101 conductively connected at one end to an output of the first transmission line 111 of the first circuit 101, the other end of the first switch 121 of the first circuit 101 being configured to be connected to a ground potential. The transmission line based switch further comprises a first switch 122 of the second circuit 102 and second 123 switch of the first circuit 101. The first switch 122 of the second circuit 102 is conductively connected at one end to an output of the first transmission line 112 of the second circuit 102, the other end of the first switch 122 of the second circuit 102 being configured to be connected to a ground potential. The second switch 123 of the first circuit 101 conductively connected at one end to an output of the transmission line 113 of the first circuit 101, the other end of the second switch 123 of the first circuit 101 being configured to be connected to a ground potential. The transmission line based switch still further comprises first 135 and second 136 output ports of the first circuit 101 and a first output port 137 of the second circuit 102. The first output port 135 of the first circuit is conductively connected to the output of the first transmission line 111 of the first circuit, the second output port 136 of the first circuit 101 is conductively connected to the output of the second transmission line 113 of the first circuit 101. The first output port 137 of the second circuit 102 is conductively connected to the output of the first transmission line 112 of the second circuit 102.

[0013] As shown within figure 1, the first output port 137 of the second circuit 102 may act as an LNA path in a PALNA application wherein the LNA path of the transmission line based switched is single ended. In such applications whole switch 100 may be employed in a transceiver wherein the first circuit 101 could act as the transmitter portion and the second circuit 102 as the receiver portion.

[0014] Relative to transformer based switches of FI 20185060, the transmission line based switches of the present invention provide wider bandwidth with otherwise similar performance. While at least some transmission line based switches are larger in size than transformer based switches, certain embodiments of the present invention employ slow- wave transmission lines in order to reduce the size of the switch as will be discussed in further embodiments below.

[0015] FIGURE 2 shows a differential transmission lined based switch 200 according to certain embodiments of the present invention. In contrast to the embodiment of figure 1, the first 201 and second 202 circuits of the switch 200 of figure 2 each contain two transmission lines. The input ports 231, 232 lead to first and second transmission lines 211, 212 and 213, 214 of the first and second circuits 201, 202 respectively. The outputs of these transmission lines then lead to first and second output ports 235, 237 and 236, 238 of the first and second circuits 201, 202 respectively. Once again the circuits comprise switches 221, 222, 223, 224 configured to be connected between outputs of the transmission lines 211, 212, 213, 214 and a ground potential. The outputs of the transmission lines further lead to output ports 235, 236, 237, 238 forming outputs 230 and 234 of the first and second circuits respectively.

[0016] When contrasted with the switch 100 of figure 1, it can clearly be seen that the switch 200 of the embodiment within figure 2 further comprises a second transmission line 214 of the second circuit 202 connected at one end to the second input port 232 and at another end to a second output port 238 of the second circuit 202. The switch 200 also comprises a second switch 224 of the second circuit 202 conductively connected at one end to an output of the second transmission line 214 of the second circuit 202, the other end of the second switch 224 of the second circuit 202 being configured to be connected to a ground potential.

[0017] At least some embodiments of the present invention implement a MMIC as shown in FIGURE 3. Once again figure 3 comprises first and second circuits 301, 302 each having first and second transmission lines: 311 and 313 for the first circuit 301, and 312 and 314 for the second circuit 302. At the output of each of the transmission lines is an output port 335 - 338 and a switch 321 - 324 configured to be connected between the output of the transmission line and a ground potential. In contrast with previous embodiments, the switch 300 of figure 3 comprises three input ports 331 - 333. The first input port is connected to both the first transmission line of the first circuit 311 and the first transmission line of the second circuit 312. The second input port 332 is connected to the second transmission line of the first circuit 312 and the third input port is connected to the second transmission line of the second circuit 314.

[0018] As also illustrated within figure 3, the switch 300 may be employed in PALNA applications wherein the first circuit 301 acts as a PA circuit and the second circuit 302 acts as an LNA circuit. Shown within figure 3, at least some switches according to the present invention also comprise power amplifiers 390 and low noise amplifiers 391 connected to their respective circuits.

[0019] FIGURE 4 shows a transmission line based switch 400 according to certain embodiments of the present invention incorporating slow-wave transmission lines and common mode chokes. Once again the switch 400 comprises first and second circuits 401, 402 each having first and second transmission lines: 411 and 413 for the first circuit 401, and 412 and 414 for the second circuit 402. However, as illustrated, within at least some embodiments of switches according to the present invention, the transmission lines are slow- wave transmission lines. As illustrated in figure 4 there are two slow- wave structures, a first circuit slow- wave structure 451 containing the first 411 and second 413 transmission lines of the first circuit 401 and a second circuit slow- wave structure 452 containing the first 412 and second 414 transmission lines of the second circuit 402.

[0020] At the output of each of the transmission lines of the switch within figure 4 is an output port 435 - 438 and a switch 421 - 424 configured to be connected between the output of the transmission line and a ground potential. Once again the switch 400 comprises three input ports 431 - 433. Also illustrated within figure 4 is an RF input pad 480 employed by at least some embodiments of the present invention.

[0021] As also illustrated within figure 4, at least some switches according to the present invention employ Radio Frequency (RF) choke inductors 442, 443 conductively connected at one end to an input port, 432 and 433 in this illustration. The other end of the RF choke inductors 442 and 443 being configured to be connected to a ground potential. The implementation of RF choke inductors improves differential operation and common mode rejection of the switch 400.

[0022] Shown in FIGURE 5, at least some switches 500 according to the present invention employ common mode chokes 561, 562. These common mode chokes may take the form of transmission lines as in figure 5. At least some embodiments employ common mode choke inductors. These common mode chokes improve differential operation of the switch.

[0023] Similar to previous embodiments, figure 5 shows a transmission line based switch 500 comprising first and second circuits 501, 502 each having first and second transmission lines: 511 and 513 for the first circuit 501, and 512 and 514 for the second circuit 502. At the output of each of the transmission lines 511 - 514 is an output port 535 - 538 and a switch 521 - 524, each switch being configured to be connected between the output of the transmission line and a ground potential. The switch 500 further comprises three input ports 531 - 533, once again implemented within an RF pad 580.

[0024] At least some embodiments of the present invention further comprise at least one common mode choke transmission line 561 connected at one end to one of the input ports, 532 or 533 in the illustration, the other end of the common mode choke transmission line 561 being configured to be connected to a ground potential.

[0025] Certain embodiments, such as the one illustrated within figure 5, further comprise two common mode chokes 561, 562. At least one common mode choke transmission line of the first circuit 561 conductively connected at one end to the second input port 532, the other end of the common mode choke transmission line of the first circuit 561 being configured to be connected to a ground potential and at least one common mode choke transmission line of the second circuit 562 conductively connected at one end to the third input port 533, the other end of the common mode choke inductor of the second circuit 562 being configured to be connected to a ground potential.

[0026] FIGURE 6 illustrates an embodiment of the present invention similar to that shown in figure 5 only the embodiment of figure 6 employs slow-wave structures. Once again a transmission line based switch 600 is shown comprising first and second circuits 601, 602 each having first and second transmission lines: 611 and 613 for the first circuit 601, and 612 and 614 for the second circuit 602. At the output of each of the transmission lines 611 - 614 is an output port 635 - 638 and a switch 621 - 624, each switch being configured to be connected between the output of its respective transmission line and a ground potential. The switch 600 further comprises three input ports 631 - 633 implemented within an RF pad 680. Common mode choke transmission lines 661, 662 are also included in each circuit.

[0027] In contrast to figure 5, as in at least some embodiments of the present invention, the common mode chokes and transmission lines of the switch 600 of figure 6 are comprised in slow- wave structures 651, 652. As illustrated the common mode choke 661 and transmission lines 611, 613 of the first circuit 601 are comprised in a first slow- wave structure 651 and the common mode choke 662 and transmission lines 612, 614 of the second circuit 602 are comprised in a second slow-wave structure.

[0028] As previously mentioned, at least some embodiments of the present invention employ slow-wave structures in place of transmission lines. In certain embodiments each transmission line is comprised in one slow wave structure, that is, all transmission lines are replaced with a single slow-wave structure. By employing slow-wave structures the overall footprint or area of the switch may be reduced.

[0029] Certain embodiments of the present invention employ quarter wavelength transmission lines.

[0030] At least some embodiments of the present invention provide for greater than 23 dB of isolation between the PA and LNA ports. Certain embodiments provide for less than 1.5 dB of insertion losses. When the PA path is on. When the LNA path is on insertion losses are less than 2.1 dB and isolation between ports is greater than 19 dB.

[0031] Within at least some embodiments of the present invention the switches are implemented as bipolar junction transistors (BJT); however a variety of different switch implementations may be employed depending on the application. For example, switches in at least some embodiments are implemented using transistors, diodes or MEMS (Micro Electro Mechanical Systems). Embodiments employing transistor switches may employ BJTs or field-effect transistors (FET), including metal-oxide-semiconductor field-effect transistors (MOSFET), metal-semiconductor field-effect transistors (MESFET) and high- electron-mobility transistors (HEMT).

[0032]

[0033] It is to be understood that the embodiments of the invention disclosed are not limited to the particular structures, process steps, or materials disclosed herein, but are extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting.

[0034] Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases“in one embodiment” or“in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment.

[0035] As used herein, a plurality of items, structural elements, compositional elements, and/or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary. In addition, various embodiments and example of the present invention may be referred to herein along with alternatives for the various components thereof. It is understood that such embodiments, examples, and alternatives are not to be construed as de facto equivalents of one another, but are to be considered as separate and autonomous representations of the present invention.

[0036] Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided, such as examples of lengths, widths, shapes, etc., to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention.

[0037] 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, and without departing from the principles and concepts of the invention. Accordingly, it is not intended that the invention be limited, except as by the claims set forth below.

[0038] The verbs“to comprise” and“to include” are used in this document as open limitations that neither exclude nor require the existence of also un-recited features. The features recited in depending claims are mutually freely combinable unless otherwise explicitly stated. Furthermore, it is to be understood that the use of "a" or "an", i.e. a singular form, throughout this document does not exclude a plurality.

ACRONYMS LIST

AC Alternating Current

BJT Bipolar Junction Transistor

FET Field-Effect Transistor

HEMT High-E lectron-Mobility T ransistor

LNA Low Noise Amplifier

MEMS Micro Electro Mechanical Systems

MESFET Metal-Semiconductor Field-Effect Transistor

MMIC MilliMeter-wave Integrated Circuit

MOSFET Metal-Oxide-Semiconductor Field-Effect Transistor

PA Power Amplifier

RF Radio Frequency

REFERENCE SIGNS LIST transmission line based switch

first circuit

second circuit

- 113 transmission lines

- 123 switches

, 132 input ports

- 137 output ports

power amplifier

low noise amplifier transmission line based switch

first circuit

second circuit

- 214 transmission lines

- 224 switches

first circuit output

, 232 input ports

second circuit output

- 238 output ports transmission line based switch

first circuit

second circuit

- 314 transmission lines

- 324 switches

- 333 input ports

- 338 output ports

power amplifier

low noise amplifier transmission line based switch

first circuit second circuit

-414 transmission lines

-424 switches

-433 input ports

-438 output ports

, 443 RF choke inductor

,452 slow-wave structure

RF pad transmission line based switch first circuit

second circuit

-514 transmission lines

-524 switches

-533 input ports

-538 output ports

, 562 common mode choke

RF pad transmission line based switch first circuit

second circuit

-614 transmission lines

-624 switches

-633 input ports

-638 output ports

, 652 slow-wave structure

, 662 common mode choke

RF pad