Limiter for broadband high-frequency signals

Abstract

Limiter (2) for high-frequency signals, comprising an input (5) and an output (6) electrically connected to the input (5) via a line section (9), wherein a high-frequency signal is supplied to the limiter (2) at its input (5), wherein the limiter (2) has at least one limiting stage (8; 81, 82, 83, 84, 8 5, 86) which is electrically connected to the input (5), where the limiting level (8; 81, 82, 83, 84, 8 5, 86) a series circuit comprising a non-biased diode (10; 101, 102, 103, 104, 105, 106) and a Zener diode (11; 111, 112, 113, 114, 115, 116), which does not serve to bias the diode, so that the high-frequency signal is electrically connected to a reference ground via the one non-biased diode (10; 101, 102, 103, 104, 105, 106) and the Zener diode (11; 111, 112, 113, 114, 115, 116), characterized by that via at least one switch (413, 414) the at least one limiting stage (8; 81, 82, 83, 84, 8 5, 86) is detachably connected to the line section (9).

Description

[0001] The invention relates to a limiter for broadband high-frequency signals, as used in particular in radio devices.

[0002] Depending on the distance between the transmitter and receiver, the reception level of a high-frequency signal at the receiver's location can vary greatly in amplitude. For example, if two vehicles, each with a radio, are driving in close proximity to each other, the amplitude of the high-frequency signal transmitted by the first vehicle and received directly by the second vehicle, among other things, can be very high. To prevent damage to the radio's reception stage, limiters are used to restrict the high-frequency signal.

[0003] US 2010 / 0277839 A1 discloses a circuit that protects a connected circuit from an excessively high amplitude of a high-frequency signal. The circuit consists of a detection unit that detects a high-frequency signal with an excessively high level, and a switching unit consisting of PIN diodes (positive intrinsic negative diodes), which limit the high-frequency signal depending on the result determined by the detection unit. A disadvantage of US 2010 / 0277839 A1 is that the circuit design is complex and requires two different circuit stages: a detection unit and a switching unit. This active control loop is also very complex due to the control transistors used and the generation of the supply voltages for the detector diodes and the control transistors.

[0004] Document DE 601 27 495 T2 discloses an integrated RF transceiver. Document JP H06-48 342 U discloses an overvoltage absorbing circuit for protecting a power amplifier at the end of a radio device, which is connected to an antenna via an antenna matching unit, from overvoltages caused by lightning strikes or the like. Document US 6 377 434 B1 discloses a secondary protection device for protecting a circuit. Document JP 2006-031 508 A discloses a contactless communication device with an RFID antenna connected to an RFID circuit and a protection circuit. Document DE 20 2007 013 457 U1 discloses a diode arrangement on a circuit board. US 6 636 404 B1 discloses an integrated overcurrent and overvoltage device for use in protecting telecommunications circuits.

[0005] It is therefore the object of the present invention to provide a limiter for a high-frequency signal which reliably protects the circuit connected to it against high amplitudes of the high-frequency signal and is very simply constructed, and to provide a radio device with such a limiter.

[0006] The object is achieved with respect to the limiter for a high-frequency signal according to the invention by the features of claim 1 and with respect to the radio device by the features of claim 13. Advantageous developments of the limiter for a high-frequency signal according to the invention are specified in the respective subclaims.

[0007] The limiter for high-frequency signals according to the invention has an input and an output electrically connected to the input via a line section, wherein a high-frequency signal is fed to the limiter at its input. The limiter also has at least one limiting stage electrically connected to the input. The limiting stage consists of a series circuit with an unbiased diode and a Zener diode, which, unlike in US 2010 / 0277839 A1, does not serve to bias the diode, so that the high-frequency signal is electrically connected to a reference ground via the one unbiased diode and the Zener diode. In contrast to US 2010 / 0277839 A1, this is a purely passive circuit that continues to function even when the supply voltage is switched off. The at least one limiting stage is detachably connected to the line section via at least one switch.

[0008] It is particularly advantageous that the limiter stage consists of a series circuit consisting of a non-biased diode and a Zener diode, which does not serve to bias the diode, because proper function requires no additional voltage sources that would have to be decoupled from the high-frequency signal. The series connection between the diode and the Zener diode reduces the high capacitance of the Zener diode by the low capacitance of the diode, which allows insertion loss to be kept low in non-limiting operation. Furthermore, the use of the series connection results in a greater increase in limiting above the breakdown voltage than when using a Zener diode alone.

[0009] Furthermore, the limiter for high-frequency signals according to the invention is advantageous if the high-frequency signal is applied to an anode of a first diode in a positive limiting stage and if the cathode of the first diode is electrically connected to a cathode of a first Zener diode and if the anode of the first Zener diode is electrically connected to the reference ground, because in this way the positive limiting stage limits a positive half-wave of the high-frequency signal. An advantage also exists if the high-frequency signal is applied to a cathode of a second diode in a negative limiting stage and if an anode of the second diode is electrically connected to an anode of a second Zener diode and if a cathode of the second Zener diode is electrically connected to the reference ground, because in this way the negative limiting stage limits a negative half-wave of the high-frequency signal.The at least one limiting stage can therefore be designed as a positive limiting stage or as a negative limiting stage.

[0010] Furthermore, it is particularly advantageous if the limiter has at least two positive limiting stages that limit a positive half-wave of the high-frequency signal and / or if the limiter has at least two negative limiting stages that limit a negative half-wave of the high-frequency signal, and / or if the at least two positive limiting stages that limit the positive half-wave and / or if the at least two negative limiting stages that limit the negative half-wave are connected to different connection points of the line section. It is particularly advantageous here that the use of multiple parallel limiting stages allows for higher thermal power dissipation.

[0011] Furthermore, it is particularly advantageous if, in the limiter according to the invention, the distance between each connection point is a quarter or approximately a quarter of the wavelength of the high-frequency signal, or if the distance between each connection point is approximately zero wavelengths. This means that when the first limiting stage, which limits, for example, a positive half-wave of the high-frequency signal and thereby reduces the potential at a first connection point to the potential of the reference ground, then the potential at a connection point that is a quarter of the wavelength of the high-frequency signal away from the first connection point again assumes a maximum, so that the Zener diode within the second limiting stage also reliably fires and limits the high-frequency signal.Limiting in subsequent limiting stages should preferably begin at a lower amplitude than in the first limiting stage, when the limiting stages are spaced approximately one-quarter of the wavelength of the high-frequency signal. Even if the spacing does not correspond exactly to one-quarter of the wavelength, the amplitude of the high-frequency signal can still be above the breakdown voltage, so the spacing is selected such that it preferably corresponds to one-quarter of the wavelength, but is still large enough that the existing amplitude of the high-frequency signal leads to limitation by the subsequent, i.e., further, spaced-apart limiting stage.

[0012] Furthermore, there is an advantage in the limiter according to the invention if a first inductance is connected into the line section, the height of which is selected such that the junction capacitance of each diode and each Zener diode within each limiting stage is compensated for a first operating frequency.

[0013] Furthermore, the limiter according to the invention is advantageous if at least one additional inductance is connected in parallel or in series with the first inductance via at least one first switch, the height of which is selected such that the junction capacitance of each diode and each Zener diode within each limiting stage is compensated for a different operating frequency. This allows several additional inductances to be connected, so that the influence of the diodes and Zener diodes is compensated at different operating frequencies.

[0014] Furthermore, the limiter according to the invention has the advantage if at least one limiting stage is electrically and separably connected to a line section via at least one second switch. This allows several additional limiting stages to be connected. These further limiting stages, which can be electrically connected, can limit the high-frequency signal, for example, to an even lower amplitude. For this purpose, Zener diodes can be used in these limiting stages. These diodes have a lower breakdown voltage than the Zener diodes used in the limiting stages that are permanently connected to the line section. The switch can also be closed when the thermal load of the other limiting stages has been reached, or so that the existing inductances and junction capacitances are compensated for a different operating frequency. The switches are, for example,PIN diodes or mechanical switches that can be operated manually, for example.

[0015] Furthermore, it is particularly advantageous in the limiter according to the invention if each diode is a PIN diode, because the junction capacitances of a PIN diode are very low. It is also particularly advantageous if the diode and / or the Zener diode have a MELF (metal electrode face) design, because this allows them to be cooled particularly easily and has a high resistance to high temperatures. It is also advantageous if the limiter includes a printed circuit board on which the at least one limiting stage is arranged, because this significantly simplifies construction and allows production to be largely automated.

[0016] It is also particularly advantageous if the limiter according to the invention has a gap pad (gap covering) and if the gap pad is arranged hermetically on the at least one limiting stage for heat absorption. The resulting low heat transfer resistance allows for reliable heat dissipation from the individual limiting stages.

[0017] The limiter according to the invention can be installed within a radio device that is additionally connected to an antenna. The limiter operates even when the radio device is disconnected from the power supply. Such a radio device can be installed, for example, in a vehicle, but also in an aircraft or a ship.

[0018] Various embodiments of the invention are described below by way of example with reference to the drawings. Identical objects have the same reference numerals. The corresponding figures of the drawing show in detail: Fig. 1 is an overview diagram of part of a radio device having the limiter for broadband radio frequency signals according to the invention; Fig. 2A shows a limiter according to the invention, which has a limiting stage that limits a positive half-wave of the high-frequency signal; Fig. 2B shows a further limiter according to the invention, which has a limiting stage that limits a positive half-wave of the high-frequency signal; Fig. 3A shows a limiter according to the invention having two limiting stages that limit a positive half-wave and a negative half-wave of the high-frequency signal; Fig. 3B shows a limiter according to the invention, which has six limiting stages arranged in parallel, which limit a positive half-wave and a negative half-wave of the high-frequency signal; Fig. 4A shows a limiter according to the invention, which has six limiting stages arranged in parallel, which limit a positive half-wave and a negative half-wave of the high-frequency signal, and which additionally includes an inductance for compensation; Fig. 4B shows a further limiter according to the invention, which has six limiting stages arranged in parallel, which limit a positive half-wave and a negative half-wave of the high-frequency signal, and which additionally includes several inductances for compensation, which can be switched on and off via a switch; and Fig. 4C shows a further limiter according to the invention, which has six limiting stages arranged in parallel, which limit a positive half-wave and a negative half-wave of the high-frequency signal, of which at least two limiting stages can be switched on and off and which additionally includes several inductances for compensation, which can be switched on and off via a switch.

[0019] Fig. 1 shows an overview circuit diagram of part of a radio device 1 that has the limiter 2 according to the invention for broadband radio-frequency signals. An antenna 3 is connected to a limiter 2 via a bandpass filter 4. The antenna 3 can optionally also be connected directly to an input 5 of the limiter 2. An output 6 of the limiter 2 is preferably connected to a low-noise amplifier (LNA) 7. The limiter 2 serves to limit high amplitudes within the radio-frequency signal received by the antenna 3 to an amplitude that is harmless to the downstream electronics. This is particularly relevant when a transmitter is arranged close to a receiver. The limiter 2 according to the invention should preferably operate without an additional power supply, so that the electronics are protected from excessively high levels even when the radio device 1 is switched off.

[0020] Fig. Figure 2A shows a limiter 2 according to the invention, which includes a limiting stage 8. It can be clearly seen that the input 5 is electrically connected to the output 6 via a conductor 9. The conductor 9 can be a printed circuit board on which the limiter 2 according to the invention is mounted. However, the conductor 9 can also be a cable, a stranded wire, or a simple wire.

[0021] The limiter 2 according to the invention has at least one limiting stage 8. This at least one limiting stage 8 consists of a series circuit of exactly one diode 10 and exactly one Zener diode 11. The diode 10 is not biased. The Zener diode 11 also does not serve to bias the diode 10. The limiting stage 8 is connected, on the one hand, to the line section 9 and thus to the input 5 and the high-frequency signal. On the other hand, the limiting stage 8 is also connected to the reference ground.

[0022] As already explained, the limiting stage 8 consists of a series circuit consisting of a diode 10 and a Zener diode 11. The limiting stage 8 does not contain any other components. In particular, no other elements are connected in series within the series circuit or to the series circuit consisting of the diode 10 and the Zener diode 11. Likewise, no other elements are connected in parallel within the series circuit or to the series circuit, apart from further limiting stages 8, as will be explained in more detail later. The elements are, on the one hand, active components, in particular transistors, which are not connected in series with the limiting stage, but also passive components, such as capacitors, which are connected in parallel with the limiting stage.

[0023] Limiting stage 8 can limit both a positive half-wave of the high-frequency signal and a negative half-wave of the high-frequency signal. If limiting stage 8 limits a positive half-wave, it will be referred to as a positive limiting stage 8. If limiting stage limits a negative half-wave, it will be referred to as a negative limiting stage. If only one limiting stage is referred to, it can be one that limits either a positive half-wave or a negative half-wave.

[0024] In the embodiment from Fig. 2A shows a limiting stage 8 that can limit the positive half-wave of the high-frequency signal. In this case, the high-frequency signal, which is present at the line section 9, is supplied via the input 5 of the limiter 2 according to the invention. The limiting stage 8 is also connected to the line section 9 via a connection point 12. The connection point 12 can be a simple branch of the conductor track on the circuit board, or a wire or stranded wire can be attached to the line section 9 by means of a soldered or welded connection.

[0025] The first diode 10 and the first Zener diode 11 are arranged such that the high-frequency signal is applied to an anode of exactly one first diode 10 of the at least one positive limiting stage 8. A cathode of the first diode 10 is electrically connected to a cathode of the first Zener diode 11. An anode of the first Zener diode 11 is electrically connected to the reference ground.

[0026] The first Zener diode 11 ensures that the high-frequency signal is not limited by the limiter 2 according to the invention at an amplitude of approximately 0.7 volts for silicon diodes. The first diode 10 and the first Zener diode 11 are selected such that the limiter 2 cuts off an amplitude of the high-frequency signal at approximately 7-8 volts. This provides protection against excessively high incoming high-frequency power, as well as overvoltages. A truncated sine wave takes on a trapezoidal shape. The first Zener diode 11 has the advantage that the output power of the high-frequency signal, as well as the stray loss, conforms to the specified specifications because its characteristic curve bends sharply at its specified voltage. An additional first diode 10 increases the attenuation factor.

[0027] The limiter 2 according to the invention only directly absorbs a portion of the truncated half-wave as energy. Rather, the majority is reflected back at the transition point to the reference ground and radiated via the antenna 3. Approximately 90% of the energy is reflected, and only approximately 10% is absorbed.

[0028] Fig. Figure 2B shows a further limiter 2 according to the invention, which has a limiting stage 8 that limits a positive half-wave of the high-frequency signal. In contrast to the limiter of Fig. 2A is the first diode 10 in Fig. 2B is a PIN diode 10. The junction capacitance of such a PIN diode 10 is significantly lower than the junction capacitance of a conventional diode.

[0029] Fig. 3A shows a limiter 2 according to the invention, which has two limiting stages 81, 82 which limit a positive half-wave and a negative half-wave of the high-frequency signal.

[0030] A positive limiting stage 81 limits a positive half-wave of the high-frequency signal. As already explained, this consists of a series circuit of exactly one first diode 101 and exactly one first Zener diode 111. The first diode 101 is preferably a first PIN diode 101.

[0031] The negative limiting stage 82 limits a negative half-wave of the high-frequency signal. The negative limiting stage 82 is connected to the line section 9 via the connection point 12. The high-frequency signal is thus applied to a cathode of a second diode 102 of the negative limiting stage 82 for the negative half-wave. An anode of the second diode 102 is electrically connected to an anode of a second Zener diode 112. A cathode of the second Zener diode 112 of the at least one negative limiting stage 82 for the negative half-wave is electrically connected to the reference ground. The second diode 102 is also preferably a second PIN diode 102. Both diodes 102 and 112 preferably have a MELF design. The negative limiting stage 82 for the negative half-wave of the high-frequency signal also absorbs only a portion of the energy of the negative half-wave.Most of the energy is also reflected by the reference ground and radiated via antenna 3.

[0032] Fig. Figure 3B shows a limiter 2 according to the invention, which has six limiting stages 81, 82, 83, 84, 85, 86 arranged in parallel, which limit a positive half-wave and a negative half-wave of the high-frequency signal. In the embodiment of Fig. 3B, the positive limiting stages 81, 83, and 85 limit the positive half-wave of the high-frequency signal, whereas the negative limiting stages 82, 84, and 86 limit the negative half-wave of the high-frequency signal. For the design of the limiting stages 81 to 86, please refer to the preceding drawings.

[0033] It can be clearly seen that the limiter 2 according to the invention has at least two positive limiting stages 81, 83, 85, in this case even three, which limit a positive half-wave of the high-frequency signal. It is also clearly evident that the limiter 2 according to the invention also has at least two negative limiting stages 82, 84, 86, in this case even three, which limit a negative half-wave of the high-frequency signal. It is obvious that the limiter 2 according to the invention has for each half-wave (positive, negative) of the high-frequency signal not just one, or two, or three, or four, or five, but n limiting stages (81, 82 to 8 n ), where n is an integer.

[0034] It is also clearly visible that the at least two positive limiting stages 81, 83 and 85, in this case three, which limit the positive half-wave and / or that the at least two negative limiting stages 82, 84 and 86, in this case three, which limit the negative half-wave, are connected to different connection points 121, 122, 123 of the line section 9. In the embodiment of Fig. 3B, the limiting stages 81, 82 are connected to the connection point 121 of the line section 9. The limiting stages 83 and 84 are connected to the connection point 122 of the line section 9. Furthermore, the limiting stages 83 and 86 are connected to the connection point 123.

[0035] It is clearly visible that the individual connection points 121, 122, and 123 are spaced apart by a length Δs. Connection point 122 is separated from connection point 121 and connection point 123 by a distance Δs. The distance Δs between each connection point 121, 122, and 123 is preferably one-quarter of the wavelength of the high-frequency signal. If the limiting stage 81 limits a positive half-wave of the high-frequency signal, the voltage at connection point 121 is pulled down to the reference ground potential.

[0036] At a distance of λ / 4, a maximum in the amplitude of the high-frequency signal is again found. This allows the limiting stage 83 or 84 to act as a limiting element. However, if the frequency is low, the required distance between each junction point 121 to 123 cannot be maintained, so that at the next junction point 122, 123, a maximum in the amplitude of the high-frequency signal may not necessarily occur again, but the amplitude is still above a threshold value at which the Zener diode 111 to 116 fires.

[0037] The separation between the individual junctions 121, 122, and 123 can also be approximately zero wavelengths. This is possible, for example, for low frequencies. In this case, approximately 50% of the energy is reflected by the limiting stages 81, 83, 85 or 82, 84, 86, approximately 30% is absorbed, and approximately 20% is transmitted.

[0038] It is also clearly visible that a positive limiting stage 81, 83, 85 is preferably connected to each junction point 121 to 123, which limits a positive half-wave of the high-frequency signal, and that a negative limiting stage 82, 84, 86 is also connected to each junction point 121 to 123, which limits a negative half-wave of the high-frequency signal. However, each limiting stage 81 to 86 can also be connected to a separate, i.e., dedicated junction point 121 to 123. In total, there can therefore be as many junction points as there are limiting stages 81 to 86.

[0039] To ensure that when a Zener diode 111 to 116 breaks down, the Zener diode 111 to 116 of the adjacent limiting stage 81 to 86 also breaks down, it is recommended to arrange the Zener diodes 111 to 116 and / or the diodes 101 to 106 as close to each other as possible. In the example from Fig. 3B, the first Zener diodes 111, 113, and 115 and / or the first diodes 101, 103, and 105 should be arranged as close to one another as possible. Likewise, the second Zener diodes 112, 114, and 116 and / or the second diodes 102, 104, and 106 should also be arranged close to one another. "Arranged close to one another" here means that the thermal power dissipation in a diode 101 to 106 and / or a Zener diode 111 to 116 heats the neighboring diode(s) 101 to 106 and / or Zener diode(s) 111 to 116 to such an extent that they also trigger.

[0040] By arranging several positive limiting stages 81, 83 and 83, as well as negative limiting stages 82, 84 and 86 of the same type in parallel, a higher power loss can be absorbed. The arrangement of Fig. 3B, for example, can easily continuously reflect power of up to 10 watts. Up to 90% is reflected and a maximum of 2 watts is absorbed. However, these values can be adjusted by selecting other Zener diodes (111 to 116) and / or other PIN diodes (101 to 106).

[0041] The limiter 2 according to the invention also has a gap pad (not shown), which is arranged as airtight as possible on the at least one limiting stage 8, preferably on all limiting stages 81 to 86, for heat dissipation. The gap pad is preferably attached to the limiting stages 81 to 86 with an adhesive.

[0042] Fig. 4A shows a limiter 2 according to the invention, which has six limiting stages 81 to 86 arranged in parallel, which limit a positive half-wave and a negative half-wave of the high-frequency signal, and which additionally includes a first inductance 40 for compensation. The first inductance 40 is connected to the input 5 on the one hand and to the line section 9 on the other. It can also be said that the first inductance 40 is connected into the line section 9. The first inductance 40 can also be connected to the output 6 on the one hand and to the line section 9 on the other. The height of the first inductance 40 is preferably selected such that the junction capacitance of each diode 101 to 106 and each Zener diode 111 to 116 within each limiting stage 81 to 86 is compensated for a first operating frequency.In the event that the high-frequency signal is a broadband signal, the height of the first inductance 40 is preferably selected such that the depletion layer capacitances are compensated for the center frequency of the high-frequency signal. The first inductance 40 is preferably also soldered to the limiter 2 according to the invention, which is designed as a circuit board. The first inductance 40 can also be formed by routing the conductor track on the circuit board. A meandering conductor track structure increases the inductance of the conductor track.

[0043] Fig. 4B shows a further limiter 2 according to the invention, which has six limiting stages 81 to 86 arranged in parallel, which limit a positive half-wave and a negative half-wave of the high-frequency signal, and which additionally has several inductors 40 n for compensation, which can be switched on and off via a switch 41. In the embodiment of the Fig. 4B, the first inductance 401 is connected to the input 5 of the limiter 2 according to the invention and to the line section 9. Parallel to this first inductance 401, n further inductances 40 n, with n ≥ 1 and integer, can be switched on or off. The further n inductances can be switched on or off individually or together with a switch 41 to the first inductance 401. The switch 41 is operated, for example, by a control unit 42. The switch 41 can be constructed, for example, using a PIN diode. It is also possible for the switch 41 to be a manual switch that is manually set by a user. In this case, the limiter 2 according to the invention can also compensate the junction capacitances of all limiter stages 81 to 86 for a different operating frequency, even if all voltage sources in the radio device 1 are switched off. By switching on one or some or all of the additional inductances 40 n the junction capacitances of the limiter stages 81 to 86 can be compensated for additional or other operating frequencies.

[0044] Fig. 4C shows a further limiter 2 according to the invention, which has six limiting stages 81 to 86 arranged in parallel, which limit a positive half-wave and a negative half-wave of the high-frequency signal, wherein at least two limiting stages 85, 86 can be switched on and off and wherein the limiter 2 according to the invention additionally has several inductors 40 n for compensation, which can be switched on and off via switches 411, 412, 413, 414. It can be clearly seen that the limiter 2 according to the invention comprises a first inductance 401 and at least one further inductance 40 n which in the embodiment of Fig. 4C can be connected in series. At least one further inductance 40 n It involves one or more individual inductors. The at least one additional inductor 40 ncan be connected in series to the first inductance 401 via the two switches 411 and 412. In the event that the inductance 40 n consists of a large number of individual inductances, one of these inductances or several of these inductances or all of these inductances 40 can be switched on via the switches 411 and 412. n be connected in series to the first inductance 401.

[0045] It is obvious that the other inductances 40 n not only be connected in series to the first inductance 401, but at the same time also in parallel to the first inductance 401, as shown in Fig. 4B has already been explained.

[0046] Furthermore, in the limiter 2 according to the invention, Fig.4C, at least one limiting stage 85, 86 each, which serves to limit the positive and negative half-waves, can be added to or removed from the high-frequency signal line section 9. For example, the positive limiting stage 85 can be electrically connected to or disconnected from the line section 9 by means of the switch 413. The same applies to the negative limiting stage 86, which can be electrically connected to or disconnected from the line section 9 via the switch 414. It is also possible for further limiting stages 81 to 86 or up to 8 ncan be connected to line section 9 by means of a switch. All switches 411 to 414 can be constructed, for example, using PIN diodes and controlled by control unit 42. Switches 411 to 414 can also consist of manual switching bridges that are set by a user. This allows the junction capacitances of the individual limiting stages 81 to 86 to be permanently compensated for a variety of operating frequencies, even without a power supply.

[0047] Incidentally, it would also be possible to integrate a suitable compensation inductance directly within each limiting stage. However, in this case, adjustment for different operating frequencies would no longer be possible.

[0048] The limiter 2 according to the invention functions seamlessly in a temperature range from -40°C to +85°C. The limiter 2 according to the invention is preferably constructed using a printed circuit board. In addition to the aforementioned gap pad, recesses can be provided in the printed circuit board directly below the diodes 101 to 106 and / or directly below the Zener diodes 111 to 116, into which a copper inlay is pressed, further reducing the thermal resistance.

[0049] The limiter 2 according to the invention shown here is preferably integrated directly into a chip. This reduces space requirements and improves heat dissipation. The power distribution can be better distributed among the individual elements.

[0050] Furthermore, all positive limiting stages 81, 83, 85, which limit the positive half-waves of the high-frequency signal, are preferably constructed identically. The same applies to all negative limiting stages 82, 84, 86, which limit the negative half-wave of the high-frequency signal. However, it is also possible for individual limiting stages 81 to 86 to have different diodes 101 to 106 and / or different Zener diodes 111 to 116, which, for example, have different breakdown voltages and / or can absorb different energies.

[0051] The limiting stages can also be constructed such that the positions of diodes 101 to 106 and Zener diodes 111 to 116 are reversed. In this case, Zener diodes 111 to 116 are electrically connected to line section 9 via connection points 121 to 123, whereas diodes 101 to 106 are electrically connected to the reference ground. Within the scope of the invention, all and / or described and / or illustrated features can be combined with one another as desired.

Claims

[1] Limiter (2) for high-frequency signals, comprising an input (5) and an output (6) electrically connected to the input (5) via a line section (9), wherein a high-frequency signal is supplied to the limiter (2) at its input (5), wherein the limiter (2) has at least one limiting stage (8; 81, 82, 83, 84, 8 5, 86) which is electrically connected to the input (5), where the limiting level (8; 81, 82, 83, 84, 8 5, 86) a series circuit comprising a non-biased diode (10; 101, 102, 103, 104, 105, 106) and a Zener diode (11; 111, 112, 113, 114, 115, 116), which does not serve to bias the diode, so that the high-frequency signal is electrically connected to a reference ground via the one non-biased diode (10; 101, 102, 103, 104, 105, 106) and the Zener diode (11; 111, 112, 113, 114, 115, 116), characterized by , that via at least one switch (413, 414) the at least one limiting stage (8; 81, 82, 83, 84, 8 5, 86) is detachably connected to the line section (9). [2] Limiter according to claim 1, characterized by , that the high-frequency signal is applied to an anode of a first diode (10; 101, 103, 105) in a positive limiting stage (8; 81, 83, 85) and that a cathode of the first diode (10; 101, 103, 105) is electrically connected to a cathode of a first Zener diode (11; 111, 113, 115) and that an anode of the first Zener diode (11; 111, 113, 115) is electrically connected to the reference ground, whereby the positive limiting stage (8;81, 83, 85) limits a positive half-wave of the high-frequency signal, and / or that the high-frequency signal is applied to a cathode of a second diode (102, 104, 106) in a negative limiting stage (82, 84, 86) and that an anode of the second diode (102, 104, 106) is electrically connected to an anode of a second Zener diode (112, 114, 116) and that a cathode of the second Zener diode (112, 114, 116) is electrically connected to the reference ground, whereby the negative limiting stage (82, 84, 86) limits a negative half-wave of the high-frequency signal.; [3] Limiter according to claim 2, characterized by , that the limiter (2) has at least two positive limiting stages (8; 81, 83, 85) which limit a positive half-wave of the high-frequency signal and / or that the limiter (2) has at least two negative limiting stages (82, 84, 86) which limit a negative half-wave of the high-frequency signal and / or that the at least two positive limiting stages (8; 81, 83, 85) which limit the positive half-wave and / or that the at least two negative limiting stages (82, 84, 86) which limit the negative half-wave are connected to different connection points (12; 121, 122, 123) of the line section (9). [4] Limiter according to claim 3, characterized by , that the at least two positive limiting stages (8; 81, 83, 85) which limit a positive half-wave of the high-frequency signal are of the same construction and / or that the at least two negative limiting stages (82, 84, 86) which limit a negative half-wave of the high-frequency signal are of the same construction. [5] Limiter according to claim 3 or 4, characterized by , that the distance (Δs) between each connection point (12; 121, 122, 123) is approximately one quarter of the wavelength of the high-frequency signal or that the distance (Δs) between each connection point (12; 121, 122, 123) is approximately zero wavelengths of the radio frequency signal. [6] Limiter according to one of claims 3 to 5, characterized by , that at each connection point (12; 121, 122, 123) a positive limiting stage (8; 81, 83, 85) is connected, which limits a positive half-wave of the high-frequency signal, and that at each connection point (12; 121, 122, 123) a negative limiting stage (82, 84, 86) is further connected, which limits a negative half-wave of the high-frequency signal. [7] Limiter according to one of claims 3 to 6, characterized byin that a first inductance (40; 401) is connected into the line section (9), the height of which inductance is selected such that the junction capacitance of each diode (10; 101, 102, 103, 104, 105, 106) and each Zener diode (11; 111, 112, 113, 114, 115, 116) within each limiting stage (8; 81, 82, 83, 84, 85, 86) is compensated for a first operating frequency. [8] Limiter according to claim 7, characterized by that at least one additional inductance (40 n ) is connected in parallel or in series to the first inductance (40; 401), the height of which is selected such that the junction capacitance of each diode (10; 101, 102, 103, 104, 105, 106) and each Zener diode (11; 111, 112, 113, 114, 115, 116) within each limiting stage (8; 81, 82, 83, 84, 85, 86) is compensated for a different operating frequency. [9] Limiter according to one of the preceding claims, characterized by , that each diode (10; 101, 102, 103, 104, 105, 106) is a PIN diode and / or that the diode (10; 101, 102, 103, 104, 105, 106) and / or the Zener diode (11; 111, 112, 113, 114, 115, 116) have a MELF design and / or that the limiter (2) includes a printed circuit board on which the at least one limiting stage (8; 81, 82, 83, 84, 85, 86) is arranged. [10] Limiter according to one of the preceding claims, characterized by that within the limitation level (8; 81, 82, 83, 84, 8 5, 86) and / or to the limiting level (8; 81, 82, 83, 84, 8 5, 86) no additional elements are connected in series with the diode (10; 101, 102, 103, 104, 105, 106) and the Zener diode (11; 111, 112, 113, 114, 115, 116) and / or that within the limiting stage (8; 81, 82, 83, 84, 8 5, 86) and / or to the limiting level (8; 81, 82, 83, 84, 8 5,86) with the exception of further limiting stages (8; 81, 82, 83, 84, 85, 86) no additional elements are connected in parallel to the diode (10; 101, 102, 103, 104, 105, 106) and the Zener diode (11; 111, 112, 113, 114, 115, 116). [11] Limiter according to claim 10, characterized by that the elements are active components, in particular transistors, and / or passive components, in particular capacitors. [12] Limiter according to one of the preceding claims, characterized by that the limiter (2) has a gap pad and that the gap pad is arranged airtight on the at least one limiting stage (8; 81, 82, 83, 84, 85, 86) for heat dissipation. [13] Radio device (1) for mobile communication comprising an antenna (3) and a limiter (2) according to one of the preceding claims, characterized by , that the antenna (3) is connected to the input (5) of the limiter (2) or that the antenna (3) is connected to the input (5) of the limiter (2) via a bandpass filter (4).

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