Amplifier device and high frequency circuit

Abstract

The invention relates to an amplifier circuit for a high frequency signal, having a topology with multiple semiconductor switching elements connected in series. The semiconductor switching elements connected in series can be safely operated close to the optimum operating range by means of the circuit design according to the invention without exceeding the breakdown voltages of the semiconductor switching elements.

Description

[0001] Description

[0002] title

[0003] Technical area

[0004] The present invention relates to an amplifier device, in particular an amplifier device for amplifying high-frequency signals. The present invention further relates to a high-frequency circuit comprising such an amplifier device.

[0005] background

[0006] Numerous high-frequency devices, such as those used in mobile communications or radar systems, require circuit components to amplify high-frequency signals. If the breakdown voltage of the individual switching elements, i.e., transistors, is below the required supply voltage, amplifier circuits with a stacked arrangement of switching elements can be used.

[0007] For example, document EP 1673858 A2 describes a technique for electrically isolated switching elements in a stacked high-frequency amplifier.

[0008] Disclosure of the invention

[0009] The present invention provides an amplifier circuit, in particular an amplifier circuit for amplifying a high-frequency signal, as well as a high-frequency switching circuit, having the features of the independent patent claims. Further advantageous embodiments are the subject of the dependent patent claims.

[0010] Accordingly, there is provided: an amplifier device for a high-frequency signal with a voltage supply device, an amplifier circuit, and a common-mode regulator. The amplifier circuit comprises an input terminal, an output terminal, a first resistor pair, a second resistor pair, a first transistor, a second transistor, a third transistor, and a fourth transistor. The first transistor is arranged between a reference potential and a first node. The second transistor is arranged between the reference potential and a second node. The third transistor is arranged between the first node and a voltage supply terminal. The fourth transistor is arranged between the second node and the voltage supply terminal. Furthermore, a positive terminal of the input terminal is coupled to a control terminal of the first transistor.Analogously, a negative terminal of the input terminal is coupled to a control terminal of the second transistor. A positive terminal of the output terminal is provided between the third transistor and the power supply terminal, and a negative terminal of the output terminal is provided between the fourth transistor and the power supply terminal. The first resistor pair comprises a first resistor and a second resistor. The first resistor is arranged between the first node and a third node. The second resistor of the first resistor pair is arranged between the third node and the second node. The second resistor pair comprises a third resistor and a fourth resistor.The third resistor is arranged between the control terminal of the third transistor and a fourth node, and the fourth resistor is arranged between the fourth node and the control terminal of the fourth transistor. The voltage supply device is designed to provide a predetermined supply voltage at a voltage supply terminal of the amplifier circuit. The common-mode regulator is designed to provide a predetermined voltage at the fourth node using a potential at the third node of the amplifier circuit. Furthermore, the following is provided:

[0011] A high-frequency circuit with an amplifier device according to the invention. For example, the high-frequency circuit can be a high-frequency circuit of a radar system or a high-frequency component for a mobile radio system.

[0012] Advantages of the invention

[0013] The present invention is based on the finding that, due to the progressive scaling of modern semiconductor technologies, the breakdown voltages between the terminals of individual transistors can decrease. At the same time, the maximum current is also limited due to, for example, electromigration and thermal conditions. On the other hand, the requirements regarding the required power in the signals for the underlying systems remain at least unchanged.

[0014] For maximum output power, the individual components should be operated as close as possible to their breakdown voltage and current limits without exceeding these limits. However, conventional approaches are increasingly reaching their limits.

[0015] It is therefore an idea of ​​the present invention to create an improved concept for an efficiently operated amplifier circuit for high-frequency signals. To this end, the present invention provides a concept that allows the amplifier device to be operated with the highest possible electrical voltage without, however, leaving the safe operating range of the semiconductor switching elements in the amplifier device, i.e., without operating the semiconductor switching elements above their breakdown voltage.

[0016] For this purpose, a supply voltage regulator is provided, which provides a supply voltage across each stacked semiconductor switching element that is lower than the sum of the breakdown voltages of the switching elements in a stacked arrangement of semiconductor switching elements. Furthermore, a common-mode regulator is provided, which enables the common-mode voltage at the control input of the stacked transistor pair to be dynamically adjusted, thus ensuring safe operation close to the operating limits.

[0017] The circuit concept according to the invention thus makes it possible to realize an amplifier arrangement in a simple manner which, on the one hand, enables optimal amplification close to the operating limit, without, on the other hand, running the risk of exceeding the operating limits and thus leaving the range of a safe operating mode.

[0018] According to one embodiment, the common-mode regulator comprises a voltage divider. The common-mode regulator is designed to provide a predetermined voltage at the fourth node using a voltage difference between one node of this voltage divider and the third node of the first resistor pair in the amplifier circuit. In other words, the common-mode regulator adjusts the voltage level at the fourth node and thus the average voltage at the control terminals of the third and fourth transistors according to the voltage at the third node and thus the average voltages at the first and second nodes. In this way, a common-mode voltage can be set that enables safe operation close to the optimal operating point.

[0019] According to one embodiment, the common-mode regulator comprises a differential amplifier. A first input of the differential amplifier can be coupled to the node of the voltage divider. Furthermore, a second input of the differential amplifier can be coupled to the third node of the amplifier circuit. The output of the differential amplifier is coupled to the fourth node of the amplifier circuit. This allows for efficient control of the common-mode gain to be implemented in a simple manner.

[0020] According to one embodiment, the voltage supply device is designed to adjust the electrical voltage at the voltage supply terminal of the amplifier circuit. In particular, the supply voltage can be adjusted based on the breakdown voltages of the transistors in the amplifier circuit. The supply voltage can be adjusted such that the supply voltage is lower than the sum of the breakdown voltages in a path of the amplifier circuit between the reference potential and the voltage supply terminal. In this way, it can be ensured that the transistors are not operated above their breakdown voltage, thus always ensuring a safe operating mode.

[0021] According to one embodiment, the voltage supply device comprises an input interface. This input interface can be designed to receive a setpoint, in particular a setpoint for the electrical voltage at the voltage supply terminal of the amplifier circuit. The voltage supply device is designed to adjust the electrical voltage at the voltage supply terminal using the received setpoint. This makes it possible, for example, to adjust the maximum value of the supply voltage for the amplifier circuit. Furthermore, by lowering the setpoint, the amplifier device can also be easily deactivated, ensuring safe operation throughout the entire switching-on and switching-off process.

[0022] According to one embodiment, the amplifier device comprises a temperature sensor. The temperature sensor can be designed to provide a sensor signal corresponding to a temperature of the amplifier device. In this case, the voltage supply terminal can be designed to adjust the electrical voltage at the voltage supply terminal of the amplifier circuit using the sensor signal for the temperature. This makes it very easy to react to temperature fluctuations and associated changed properties in the amplifier device. This enables additional optimization of the operating behavior. According to one embodiment, several pairs each consisting of a third transistor and a fourth transistor are provided in the amplifier circuit. An individual common-mode regulator is provided for each pair of a third transistor and a fourth transistor.By connecting several such transistor pairs in series, the maximum possible operating voltage and thus the resulting output power of the signal can be further increased.

[0023] According to one embodiment, the device comprises a parameterizable current source circuit. This current source circuit is designed to provide a predetermined voltage or a predetermined voltage waveform at the control terminals of the first transistor and the second transistor of the amplifier circuit. In particular, this allows operating point voltage waveforms with suitable temporal dynamics to be provided at the control terminals of the first and second transistors in order to ensure the functionality of the common-mode control and thus a safe operating mode even in the event of current changes.

[0024] According to one embodiment, the transistors of the amplifier circuit are each field-effect transistors. Alternatively, the transistors can also be designed as bipolar transistors.

[0025] According to one embodiment, the amplifier device is implemented as an integrated circuit. In particular, the amplifier device can be integrated in a system-on-chip or a monolithic microwave integrated circuit (MMIC).

[0026] The above embodiments and developments can be combined with each other as desired, where appropriate. Further embodiments, developments, and implementations of the invention also include combinations of features of the invention not explicitly mentioned above or described below with respect to the exemplary embodiments. In particular, those skilled in the art will also add individual aspects as improvements or additions to the respective basic forms of the invention. Brief Description of the Drawings

[0027] Further features and advantages of the invention are explained below with reference to the figures.

[0028] Fig. 1 : a schematic representation of an amplifier device according to an embodiment; and

[0029] Fig. 2: a time course diagram to illustrate the

[0030] Functional principle of the amplifier device according to the invention.

[0031] Description of embodiments

[0032] Figure 1 shows a schematic representation of a circuit concept for an amplifier device 1 according to one embodiment. The basic structure of the amplifier device 1 can, in principle, be divided into several blocks. The amplifier device 1 comprises an amplifier circuit 10, which can be supplied with an electrical voltage by a voltage supply device 20. Furthermore, at least one common-mode regulator 30 is provided. Furthermore, the amplifier device 1 can comprise a current source circuit 40.

[0033] The amplifier device 1 can be used, for example, to amplify a high-frequency signal. For example, the amplifier device 1 can be used for amplifying high-frequency signals in a radar system or a high-frequency component for a mobile radio system. Of course, an amplifier device 1 with the basic principle according to the invention can also be used for any other suitable applications. In particular, the amplifier device 1 can be implemented, for example, as a system-on-chip or in a monolithic microwave integrated circuit (MMIC).

[0034] The amplifier circuit 10 comprises an input terminal with a positive connection point Ip and a negative connection point In. An input-side high-frequency signal can be provided between these two connection points In and Ip. The amplified output signal is output at an output terminal between the positive connection point Op and the negative connection point On. For power supply, the power supply device 20 can provide an operating voltage at a power supply terminal 19.

[0035] The amplifier device 10 comprises a first pair of transistors T1p, T1n, and at least one further pair of transistors T2p, T2n. A first transistor T1p of the first pair of transistors is arranged between a reference potential and a first node K1p. In parallel, a second transistor T1n of the first pair of transistors is arranged between the reference potential and a second node K1n.

[0036] A first transistor T2p of the second pair of transistors is arranged between the first node K1p and the voltage supply terminal 19. An inductor L2p can be provided between the transistor T2p and the voltage supply terminal 19. The positive output terminal Op is connected to the connection point between the transistor T2p and the inductor L2p. Similarly, a second transistor T2n of the second pair of transistors is arranged between the second node K1n and the voltage supply terminal 19. Here, too, an inductor L2n can be provided between the transistor T2n and the voltage supply terminal 19.

[0037] Accordingly, the negative terminal On of the output terminal is connected to the connection point between the transistor T2n and the inductance L2n.

[0038] The amplifier device 10 further comprises a first resistor pair, wherein a first resistor R1p of the resistor pair is provided between the first node K1p and a third node K3, and a second resistor R1n of the resistor pair is provided between the third node K3 and the second node K1n. Furthermore, a second resistor pair is provided between the control terminals of the transistors T2p, T2n of the second pair of transistors. Here, a resistor is provided between the control terminal of the first transistor T2p of the second pair of transistors and a fourth node K4. Another resistor is provided between the control terminal of the second transistor T2n and the fourth node.

[0039] The arrangement of the two pairs of resistors and the second pair of transistors T2p, T2n forms an amplifier stage 11. If necessary, several such amplifier stages 11 can be provided in series. In this case, a separate common-mode regulator 20 is provided for each amplifier stage 11.

[0040] The common-mode regulator 30 can provide a common-mode voltage at the fourth node K4. This common-mode voltage can be adjusted, in particular, using the potential at the third node K3. For this purpose, a differential amplifier 33 can be provided, for example, in the common-mode regulator 30. A (positive) input terminal of the differential amplifier 33 can be coupled to a node of a voltage divider comprising the resistors 31 and 32 in the common-mode regulator 30. This voltage divider can be arranged between the voltage supply terminal 19 of the amplifier circuit 10 and the reference potential. Another (negative) input terminal of the differential amplifier 33 can be electrically coupled to the third node K3 of the first resistor pair in the amplifier circuit 10.The output terminal of the differential amplifier 33 can be electrically coupled to the fourth node K4 of the second resistor pair between the two control terminals of the transistors T2p, T2n of the second pair of transistors.

[0041] The voltage supply device 20 can provide an electrical operating voltage V_reg at the voltage supply terminal 19 of the amplifier circuit 10. This operating voltage V_reg can be controlled such that it is always below a predetermined threshold value. This threshold value can be selected such that the maximum operating voltage V_reg is always less than the sum of the breakdown voltages of the transistors T1 p, T2 p or T1 n, T2 n in a path between the reference potential and the voltage supply terminal 19. For this purpose, for example, a transistor 21 can be provided between the positive supply voltage VDD and the voltage supply terminal 19. This transistor 21 can be controlled at its control terminal such that the desired voltage regulation can be achieved. For example, a suitable driver circuit 22 can be provided for this purpose.

[0042] In particular, an input interface 29 can be provided in the voltage supply device 20. For example, a setpoint value V_des for the (maximum) operating voltage of the amplifier circuit 10 can be provided at this input interface 29. In this case, the voltage regulation of the voltage supply device 20 can be carried out using this setpoint value V_des.

[0043] If necessary, a sensor value T from a temperature sensor 2 can also be provided to the voltage supply device 20. Such a temperature sensor 2 can, for example, be positioned at a suitable position on the amplifier device 1. In this case, the voltage supply device 20 can also regulate the operating voltage V_reg using this sensor value T from the temperature sensor 2. This can, for example, compensate for variations, drifts, or the like due to temperature fluctuations.

[0044] The current source circuit 40 can be coupled to a fifth node K5 between the control terminals of the two transistors T1p, T1n of the first pair of transistors. For this purpose, for example, a first inductance L1p can be provided between the control terminal of the first transistor T1p and the node K5, and a second inductance can be provided between the node K5 and the control terminal of the second transistor T1n. The electrical voltage provided at the fifth node K5 can thus control the electrical current through the two transistors T1p, T1n of the first pair of transistors. A possible configuration in the form of a current mirror circuit is illustrated by way of example in the schematic circuit concept according to block 40 in Figure 1. The driver circuit 41 controls a first transistor 43 of the current source circuit 40.This creates a potential at the junction point between the first transistor 43 and the second transistor 44, which is transferred to the fifth node K5 of the amplifier circuit 10. This allows the electrical current through the two transistors T1 p, T1 n of the first pair of transistors to be adjusted.

[0045] Furthermore, a component 42 for generating voltage ramps can be provided, for example, on the input side of the current source circuit 40. In this way, the current regulation can be controlled on the output side in the form of minimum current, maximum current, and defined ramp steepnesses. Such a slow change in the current when switching the amplifier circuit 10 on and off in the form of defined current ramps enables the common-mode regulator 30 to follow the current changes and thus the voltage changes within the amplifier circuit 10 quickly enough without leaving the safe operating range of the transistors T1p, T1n, T2p, T2n.

[0046] Furthermore, it is also important for common-mode control that a small minimum current continues to flow in standby mode. After an activation time (time t2 in Figure 2 described below), the current oscillates slowly, ramp-like, between the two states.

[0047] Figure 2 shows a schematic representation of a time course diagram to illustrate the functional principle of the amplifier device 1 according to the invention, as previously described in connection with Figure 1.

[0048] The first line I represents an activation signal. Below this, line II represents a digital control variable for a setpoint V_des for the voltage supply device 20. The third line III represents the activation signal for the common-mode regulator 30. The fourth line IV represents the control signals for the current source circuit 40.

[0049] Below, the fifth line (V) shows the voltage waveform V_reg of the operating voltage at the power supply terminal 19. The sixth line (VI) illustrates the voltage waveform at the fourth node K4 between the control terminals of the transistors T2p, T2n of the second pair of transistors. Finally, the seventh and final line (VII) illustrates the electrical current at the power supply terminal 19.

[0050] At time t1, the amplifier device 1 is activated by the activation signal shown in line I. As can be seen in line V, the electrical voltage V_reg at the voltage supply terminal 19 then rises to a first, low value according to the setpoint V_des. This first voltage value according to the setpoint V_des is below the breakdown voltage of the individual transistors in the amplifier circuit 10. In this way, it can be ensured that safe operation is always guaranteed, even when the common-mode regulator 20 is deactivated. After the common-mode regulator 20 is activated at time t2 according to the signal in line III, a voltage is also present at the control terminals of the transistors T2p, T2n of the second pair of transistors (cf. line VI), which leads to an initially low current flow according to line VII.

[0051] Subsequently, at time t3, the setpoint V_des for the operating voltage is increased, whereupon this operating voltage V_reg rises at the voltage supply terminal 19. Due to the feedback in the common-mode regulator 20, the electrical voltage at the fourth node K4 between the control terminals of the two transistors T2p, T2n of the second pair of transistors also increases.

[0052] After a stable operating state has been established, the current source circuit 40 can increase the potential at the control terminals of transistors T1 p, T1 n of the first pair of transistors at time t4, so that the electric current through these transistors T1 p, T1 n and thus in the entire amplifier circuit 10, in particular also at the voltage sensor 19, also increases. If this phase ends, for example, at time t5, the electric current decreases again accordingly.

[0053] Thus, for example, the amplifier device 1 can be activated by the current source circuit 40, as occurs, for example, at times t4, or deactivated, as occurs, for example, at times t5. In the intermediate phases, the amplifier device 1 is in a kind of standby mode, with the control by the common-mode regulator 30 still being in a stable state.

[0054] For complete deactivation, for example, the setpoint V_des for the supply voltage V_reg can first be lowered at time t6 and then the common-mode regulators can also be deactivated at time t7.

[0055] In summary, the present invention relates to an amplifier circuit for a high-frequency signal with a topology of several series-connected semiconductor switching elements. With the circuit concept according to the invention, the series-connected semiconductor switching elements can be reliably operated close to the optimal operating range without exceeding the breakdown voltages of the semiconductor switching elements.

Claims

Claims 1. An amplifier device (1) for a high-frequency signal, comprising: a voltage supply device (20); an amplifier circuit (10); and a common-mode regulator (30), wherein the amplifier circuit (10) comprises an input terminal, an output terminal, a first resistor pair, a second resistor pair, a first transistor (T1 p), a second transistor (T1 n), a third transistor (T2 p), and a fourth transistor (T2 n), wherein the first transistor (T1 p) is arranged between a reference potential and a first node (K1 p), the second transistor (T1 n) is arranged between the reference potential and a second node (K1 n), the third transistor (T2 p) is arranged between the first node (K1 p) and a voltage supply terminal (19), and the fourth transistor (T2 n) is arranged between the second node (K1 n) and the voltage supply terminal (19).wherein a positive terminal (Ip) of the input terminal is coupled to a control terminal of the first transistor (T1 p), and a negative terminal (In) of the input terminal is coupled to a control terminal of the second transistor (T1 n), wherein a positive terminal (Op) of the output terminal is arranged between the third transistor (T2 p) and the voltage supply terminal (19), and a negative terminal (On) of the output terminal is arranged between the fourth transistor (T2 n) and the voltage supply terminal (19), wherein the first resistor pair comprises a first resistor (R1 p) arranged between the first node (K1 p) and a third node (K3), and a second resistor (R1 n) arranged between the third node (K3) and the second node (K1 n), wherein the second resistor pair comprises a third resistor (R2 p) arranged between the control terminal of the third transistor (T2 p) and a fourth node (K4), and a fourth resistor (R2 n) arranged between the fourth node (K4) and the control terminal of the fourth transistor (T2 n); wherein the voltage supply device (20) is designed to provide a predetermined supply voltage (V_reg) at a voltage supply terminal (19) of the amplifier circuit (10);wherein the common mode regulator (30) is designed to provide a predetermined voltage at the fourth node (K4) using a potential at the third node (K3) of the amplifier circuit (10); 2. Amplifier device (1) according to claim 1, wherein the common-mode regulator (30) comprises a voltage divider, and the common-mode regulator (30) is designed to provide a predetermined voltage at the fourth node (K4) using a voltage difference between a node of the voltage divider and the third node (K3) of the first resistor pair in the amplifier circuit (10).

3. Amplifier device (1) according to claim 2, wherein the common-mode regulator (30) comprises a differential amplifier (33), and wherein a first input of the differential amplifier (33) is coupled to the node of the voltage divider, and a second input of the differential amplifier (33) is coupled to the third node (K3) of the amplifier circuit (10), and wherein the output of the differential amplifier (33) is coupled to the fourth node (K4) of the amplifier circuit (10).

4. Amplifier device (1) according to one of claims 1 to 3, wherein the voltage supply device (20) is designed to adjust the electrical voltage (V_reg) at the voltage supply terminal (19) of the amplifier circuit (10) based on the breakdown voltages of the transistors (T1 p, T2 p, T1 n, T2 n) in the amplifier circuit (10).

5. Amplifier device (1) according to one of claims 1 to 4, wherein the voltage supply device (20) comprises an input interface (29) which is designed to receive a setpoint value (V_des) for the electrical voltage at the voltage supply terminal (19) of the amplifier circuit (10), and wherein the voltage supply device (20) is designed to adjust the electrical voltage at the voltage supply terminal (19) using the received setpoint value (V_des).

6. Amplifier device (1) according to one of claims 1 to 5, a temperature sensor (2) which is designed to provide a sensor signal corresponding to a temperature of the amplifier device (1), wherein the voltage supply device (20) is designed to adjust the electrical voltage at the voltage supply terminal (19) of the amplifier circuit (10) using the sensor signal for the temperature.

7. Amplifier device (1) according to one of claims 1 to 6, wherein a plurality of pairs each comprising a third transistor (T2p) and a fourth transistor (T2n) are provided in the amplifier circuit (10), and wherein an individual common-mode regulator (30) is provided for each pair of a third transistor (T2p) and a fourth transistor (T2n).

8. Amplifier device (1) according to one of claims 1 to 7, comprising a current source circuit (40) which is designed to provide a predetermined voltage or a predetermined voltage curve at the control terminals of the first transistor (T1 p) and the second transistor (T1 n) of the amplifier circuit (10).

9. Amplifier device (1) according to one of claims 1 to 8, wherein the amplifier device (1) is integrated in an integrated circuit, in particular in a system-on-chip or a monolithic integrated microwave circuit 10. High-frequency circuit comprising an amplifier device according to one of claims 1 to 9.

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