Radio frequency power amplifier and standing wave protection circuit thereof

Abstract

The utility model discloses a radio frequency power amplifier and a standing wave protection circuit thereof, the radio frequency power amplifier comprises a power amplification circuit and a coupler which are sequentially connected between a radio frequency input end and a radio frequency output end, and the coupler outputs reflection power of the radio frequency power amplifier. The standing wave protection circuit comprises an attenuation circuit, wherein the input end of the attenuation circuit is connected with the output end of the reflection power; the input end of the detection amplification circuit is connected with the output end of the attenuation circuit through a first capacitor; the input end of the output power control circuit is connected with the output end of the detection amplification circuit, the output end of the output power control circuit is connected with the bias end of the power amplification circuit, and the output power control circuit is used for controlling the power amplification circuit to adjust the output power when the reflection power is larger than or equal to a set threshold value. Therefore, the radio frequency power amplifier can be prevented from being burnt down when the standing wave generated by the load is abnormal, and certain power output is kept.

Description

Technical Field

[0001] This utility model relates to the field of radio frequency technology, and in particular to a radio frequency power amplifier and its standing wave protection circuit. Background Technology

[0002] With the rapid development of modern communication technology, radio frequency power amplifiers are constantly evolving towards miniaturization and lower cost. This evolutionary trend brings higher power density, but at the same time, it also places more stringent requirements on overall efficiency and thermal design.

[0003] In existing technologies, circulators or isolators are generally used to control the output impedance of RF power amplifiers. However, circulators and isolators are typically expensive, occupy a large installation area, and have limited bandwidth, making them unsuitable for high-frequency and broadband communication requirements. Furthermore, these devices are relatively heavy, hindering the miniaturization and lightweight design of RF power amplifiers. However, without an isolator or circulator at the output of the RF power amplifier, an open circuit, short circuit, or deterioration of the standing wave ratio at the output could potentially burn out the amplifier.

[0004] Therefore, a new radio frequency power amplifier and its standing wave protection circuit are needed to solve the above problems. Utility Model Content

[0005] In view of the above problems, the purpose of this utility model is to provide an RF power amplifier and its standing wave protection circuit, so as to prevent the RF power amplifier from being burned out when the standing wave generated by the load is abnormal, and to maintain a certain power output.

[0006] According to one aspect of this utility model, a standing wave protection circuit for an RF power amplifier is provided. The RF power amplifier includes a power amplifier circuit and a coupler connected sequentially between an RF input terminal and an RF output terminal. The coupler outputs the reflected power of the RF power amplifier. The standing wave protection circuit includes an attenuation circuit, the input terminal of which is connected to the output terminal of the reflected power; a detector amplifier circuit, the input terminal of which is connected to the output terminal of the attenuation circuit via a first capacitor; and an output power control circuit, the input terminal of which is connected to the output terminal of the detector amplifier circuit, and the output terminal of which is connected to the bias terminal of the power amplifier circuit. The control circuit is used to adjust the output power of the power amplifier circuit when the reflected power is greater than or equal to a set threshold.

[0007] Optionally, the output power amplifier circuit includes a voltage divider circuit connected between the power supply terminal and the ground terminal, the voltage divider circuit having a voltage divider node; a threshold detection circuit, the input terminal of which is connected to the output terminal of the detector amplifier circuit, used to detect whether the reflected power is greater than or equal to the set threshold; and a pull-down circuit connected between the bias terminal and the ground terminal of the power amplifier circuit, the control terminal of which is connected to the output terminal of the threshold detection circuit and to the voltage divider node, used to pull down the voltage of the bias terminal of the power amplifier circuit by lowering the voltage of the voltage divider node when the threshold detection circuit detects that the reflected power is greater than or equal to the set threshold.

[0008] Optionally, the voltage divider circuit includes a first resistor and a second resistor connected sequentially between the voltage terminal and the ground terminal, and the common node of the first resistor and the second resistor is the voltage divider node; the pull-down circuit includes a third resistor, a fourth resistor, and a transistor connected sequentially between the bias terminal and the ground terminal of the power amplifier circuit, the common node of the third resistor and the fourth resistor is connected to the voltage divider node, and the base of the transistor is connected to the output terminal of the threshold detection circuit.

[0009] Optionally, the threshold detection circuit has a first input terminal, a second input terminal, a first output terminal, and a second output terminal. Its second input terminal is connected to the output terminal of the detector amplifier circuit, its first output terminal is connected to the base of the transistor, and its first input terminal is connected to its second output terminal.

[0010] Optionally, the attenuation circuit includes a fifth resistor, with its first end connected to the output terminal of the reflected power and its second end connected to the first capacitor; a sixth resistor connected between the first end of the fifth resistor and the ground terminal; and a seventh resistor connected between the second end of the fifth resistor and the ground terminal.

[0011] Optionally, the detection amplification circuit includes a detector, the input pin of which is connected to the output terminal of the attenuation circuit via the first capacitor; and an amplification circuit, the input terminal of which is connected to the output pin of the detector, and the output terminal of which is connected to the input terminal of the output power control circuit.

[0012] Optionally, the amplification circuit includes an operational amplifier, an eighth resistor, and a ninth resistor. The non-inverting input of the operational amplifier is connected to the output pin of the detector, the output of the operational amplifier is connected to the ground terminal via the eighth and ninth resistors, and the inverting input of the operational amplifier is connected to the common node of the eighth and ninth resistors.

[0013] Optionally, the detector amplification circuit further includes a first filter circuit connected between the output pin of the detector and the input terminal of the amplification circuit; and a second filter circuit connected between the power supply terminal and the power supply pin of the detector.

[0014] Optionally, the first filter circuit includes a tenth resistor and a second capacitor. The first end of the tenth resistor is connected to the output pin of the detector, and the second end of the tenth resistor is connected to the input pin of the amplifier circuit. The second capacitor is connected between the second end of the tenth resistor and the ground terminal. The second filter circuit includes an inductor connected between the power supply terminal and the power supply pin of the detector, a third capacitor connected between the power supply terminal and the ground terminal, and a fourth capacitor connected between the power supply terminal and the ground terminal.

[0015] According to another aspect of the present invention, a radio frequency power amplifier is provided, comprising a power amplification circuit including a pre-drive amplifier, a drive amplifier, and a final stage amplifier sequentially connected between a radio frequency input terminal and a radio frequency output terminal; a coupler disposed between the power amplifier and the radio frequency output terminal, wherein a load is connected between a first output terminal and a ground terminal, the first output terminal outputs positive power, and the second output terminal outputs reflected power; and a standing wave protection circuit as described above, wherein the standing wave protection circuit is connected between the second output terminal of the coupler and the bias terminal of the pre-drive amplifier.

[0016] The present invention provides an RF power amplifier and its standing wave protection circuit, comprising an attenuation circuit, the input of which is connected to the output of the reflected power; a detector amplification circuit, the input of which is connected to the output of the attenuation circuit via a first capacitor; and an output power control circuit, the input of which is connected to the output of the detector amplification circuit, and the output of which is connected to the bias terminal of the power amplifier circuit. This control circuit adjusts the output power of the power amplifier circuit when the reflected power is greater than or equal to a set threshold, thereby preventing the RF power amplifier from burning out when abnormal standing waves are generated by the load, and maintaining a certain power output. Attached Figure Description

[0017] The above and other objects, features and advantages of the present invention will become clearer from the following description of embodiments of the present invention with reference to the accompanying drawings, in which:

[0018] Figure 1 A schematic diagram of the structure of a radio frequency power amplifier according to an embodiment of the present invention is shown;

[0019] Figure 2 A circuit diagram of a radio frequency power amplifier according to an embodiment of the present invention is shown. Detailed Implementation

[0020] Various embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. In the various drawings, the same elements or modules are indicated by the same or similar reference numerals. For clarity, the various parts in the drawings are not drawn to scale.

[0021] It should be understood that, in the following description, "circuit" may include single or combined hardware circuits, programmable circuits, state machine circuits, and / or elements capable of storing instructions executed by the programmable circuit. When an element or circuit is said to be "connected" to another element or "connected" between two nodes, it may be directly coupled or connected to the other element, or there may be intermediate elements; the connection between elements may be physical, logical, or a combination thereof. Conversely, when an element is said to be "directly coupled to" or "directly connected" to another element, it means that there are no intermediate elements between them.

[0022] Furthermore, certain terms are used in this patent specification and claims to refer to specific components. Those skilled in the art will understand that hardware manufacturers may use different names to refer to the same component. This patent specification and claims do not distinguish components based on differences in name, but rather on differences in function.

[0023] Furthermore, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0024] Figure 1 A schematic diagram of the structure of a radio frequency power amplifier according to an embodiment of the present invention is shown.

[0025] See Figure 1 The radio frequency power amplifier 100 provided in this embodiment includes a radio frequency input terminal RF_IN, a power amplification circuit 110, a coupler 120, a radio frequency output terminal RF_OUT, and a standing wave protection circuit 130. The power amplification circuit 110 includes a multi-stage amplifier connected in series. For example, the radio frequency power amplifier 100 can be a gallium nitride (GaN) radio frequency power amplifier, a silicon germanium (SiGe) radio frequency power amplifier, etc. The radio frequency input terminal RF_IN is connected to a radio frequency transmitter, and the radio frequency output terminal RF_OUT is connected to an antenna.

[0026] The input terminal of power amplifier circuit 110 is connected to the RF input terminal RF_IN, and the output terminal of power amplifier circuit 110 is connected to the RF output terminal RF_OUT. Coupler 120 is disposed between the output terminal of power amplifier circuit 110 and the RF output terminal RF_OUT. Power amplifier circuit 110 is used to amplify the power of the RF input signal. Coupler 120 is used to split the output power of power amplifier circuit 110 into two paths. That is, coupler 120 samples the output power of power amplifier circuit 110 and outputs positive power from its first output terminal and reflected power from its second output terminal. A load R1 is connected between the first output terminal of coupler 120 and the ground terminal.

[0027] The standing wave protection circuit 130 includes an attenuation circuit 131, a detection and amplification circuit 132, and an output power control circuit 133. The input terminal of the attenuation circuit 131 is connected to the second output terminal of the coupler 120, the output terminal of the attenuation circuit 131 is connected to the input terminal of the detection and amplification circuit 132, the output terminal of the detection and amplification circuit 132 is connected to the input terminal of the output power control circuit 133, and the output terminal of the output power control circuit 133 is connected to the bias terminal of the power amplifier circuit 110.

[0028] Attenuation circuit 131 attenuates the received reflected power to a level suitable for connection to detector amplifier circuit 132. For example, attenuation circuit 131 attenuates the reflected power to 10 dB. Detector amplifier circuit 132 amplifies the attenuated reflected power to obtain a detected amplified signal. Output power control circuit 133 adjusts the output power of power amplifier circuit 110 when the reflected power is greater than or equal to a set threshold. Specifically, output power control circuit 133 can either turn off power amplifier circuit 110 or simply reduce the output power of power amplifier circuit 110.

[0029] Figure 2 A circuit diagram of a radio frequency power amplifier according to an embodiment of the present invention is shown.

[0030] See Figure 2 The power amplifier circuit 110 includes a pre-drive amplifier 111, a drive amplifier 112, and a final stage amplifier 113, which are sequentially connected between the RF input terminal RF_IN and the RF output terminal RF_OUT. For example, the pre-drive amplifier 111 includes a power amplifier transistor, the gate of which is connected as the bias terminal of the power amplifier circuit 110 to the output terminal of the standing wave protection circuit 130.

[0031] The attenuation circuit 131 includes resistors R2-R4, which form a π-type attenuator. It is understood that the attenuation circuit 131 is not limited to a π-type attenuator; it can also be any existing attenuator such as a bridge T attenuator or a PIN diode attenuator. The first end of resistor R2 is connected to the second output terminal of coupler 120, resistor R3 is connected between the first end of resistor R2 and ground, and resistor R4 is connected between the second end of resistor R2 and ground. Furthermore, a capacitor C1, which is a DC blocking capacitor, is connected between the attenuation circuit 131 and the detection and amplification circuit 132.

[0032] The detection and amplification circuit 132 includes a detector 132a and an amplifier circuit 132d. The input pin RFIN of detector 132a is connected to the output terminal of attenuation circuit 131 (the second end of resistor R2) via capacitor C1. The output pin DCOUT of detector 132a is connected to the input terminal of amplifier circuit 132d. Detector 132a is used to detect the reflected power after attenuation by attenuation circuit 131 to obtain a detected signal. Amplification circuit 132d is used to amplify the detected signal to obtain an amplified detected signal. The amplification factor of amplifier circuit 132d can be set as needed. For example, detector 132a uses a GPQ6040.

[0033] Furthermore, a filter circuit 132b is connected between the output pin DCOUT of detector 132a and the input terminal of amplifier circuit 132d. A filter circuit 132c is also connected between the power supply pin VDD of detector 132a and the power supply terminal VCC. The power supply terminal VCC provides, for example, a 5V power supply voltage.

[0034] Filter circuit 132b includes capacitor C4 and resistor R5, which together form an RC filter. Amplifier circuit 132d includes operational amplifier COMP, resistors R6 and R7. Filter circuit 132c includes inductor L, capacitor C2, and capacitor C3. The first end of resistor R5 is connected to the output pin DCOUT of detector 132a, and capacitor C4 is connected between the second end of resistor R5 and ground. The non-inverting input of operational amplifier COMP is connected to the second end of resistor R5, the output of operational amplifier COMP is connected to ground via resistors R6 and R7, and the inverting input of operational amplifier COMP is connected to the midpoint between resistors R6 and R7. Inductor L is connected between power supply terminal VCC and power supply pin VDD of detector 132a, capacitor C2 is connected between power supply terminal VCC and ground, and capacitor C3 is connected between power supply terminal VCC and ground. Capacitors C2 and C3 are filter capacitors.

[0035] The output power control circuit 133 includes a threshold detection circuit 133a, a voltage divider circuit, and a pull-down circuit. The voltage divider circuit is connected between the power supply terminal VCC and the ground terminal, and has a voltage divider node. The pull-down circuit is connected between the bias terminal and the ground terminal of the power amplifier circuit 110. The input terminal of the threshold detection circuit 133a is connected to the output terminal of the detector amplifier circuit 132, i.e., the output terminal of the operational amplifier COMP, and the output terminal of the threshold detection circuit 133a is connected to the control terminal of the pull-down circuit. The threshold detection circuit 133a is used to flip its output level to a high level when the reflected power represented by the detector amplifier signal is greater than or equal to a set threshold, so as to control the pull-down circuit to conduct, so that the pull-down circuit pulls down the voltage of the bias terminal of the power amplifier circuit 110 by lowering the voltage of the voltage divider node, thereby reducing the output power of the power amplifier circuit 110.

[0036] The threshold detection circuit 133a is implemented, for example, by using a dual-channel inverting Schmitt trigger. Taking 74LVC2G14GW as an example, its second input terminal 2A is connected to the output terminal of the detection amplifier circuit 132 as the input terminal of the threshold detection circuit 133a. Its first output terminal 1Y is connected to the control terminal of the pull-down circuit as the output terminal of the threshold detection circuit 133a. Its second output terminal 2Y is connected to its first input terminal 1A. Its power supply terminal VDD is connected to the power supply terminal VCC (not shown in the figure), and its ground terminal GND is grounded (not shown in the figure).

[0037] The voltage divider circuit includes resistors R10 and R8 connected sequentially between the power supply terminal VCC and the ground terminal, with the common node of resistors R10 and R8 serving as the voltage divider node. The pull-down circuit includes resistors R11 and R9 connected sequentially between the bias terminal and the ground terminal of the power amplifier circuit 110, and a transistor Q1. The base of transistor Q1 is connected to the output terminal of the threshold detection circuit 133a. When the output signal of the threshold detection circuit 133a flips to a high level, transistor Q1 conducts, pulling down the voltage at the voltage divider node, thereby pulling down the bias terminal voltage of the pre-drive amplifier. The output power of the power amplifier circuit 100 when transistor Q1 is conducting can be set by adjusting the values ​​of resistors R8-R10.

[0038] The radio frequency power amplifier and its standing wave protection circuit provided in this embodiment of the invention can reduce the output power of the radio frequency power amplifier when the standing wave generated by the load is abnormal. Thus, the radio frequency power amplifier can be protected from being burned out even when there is no isolator or circulator at the output of the radio frequency power amplifier. It can also maintain a certain power output to reduce the impact on communication.

[0039] The embodiments of this utility model described above are examples of specific examples, and do not exhaustively describe all details, nor do they limit the utility model to only specific embodiments. Obviously, many modifications and variations can be made based on the above description. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of this utility model, thereby enabling those skilled in the art to make good use of this utility model and its modifications. The scope of protection of this utility model should be determined by the scope defined by the claims of this utility model and their equivalents.

Claims

1. A standing wave protection circuit for a radio frequency (RF) power amplifier, the RF power amplifier comprising a power amplifier circuit and a coupler sequentially connected between an RF input terminal and an RF output terminal, the coupler outputting the reflected power of the RF power amplifier, characterized in that, The standing wave protection circuit includes: The attenuation circuit has its input terminal connected to the output terminal of the reflected power. The input terminal of the detector amplifier circuit is connected to the output terminal of the attenuation circuit via a first capacitor. An output power control circuit, with its input terminal connected to the output terminal of the detector amplifier circuit and its output terminal connected to the bias terminal of the power amplifier circuit, is used to control the power amplifier circuit to adjust its output power when the reflected power is greater than or equal to a set threshold.

2. The standing wave protection circuit according to claim 1, characterized in that, The output power amplifier circuit includes: A voltage divider circuit is connected between the power supply terminal and the ground terminal, and the voltage divider circuit has a voltage divider node; A threshold detection circuit, with its input terminal connected to the output terminal of the detector amplifier circuit, is used to detect whether the reflected power is greater than or equal to the set threshold. A pull-down circuit is connected between the bias terminal and the ground terminal of the power amplifier circuit. The control terminal is connected to the output terminal of the threshold detection circuit and to the voltage divider node. When the threshold detection circuit detects that the reflected power is greater than or equal to a set threshold, the voltage of the bias terminal of the power amplifier circuit is pulled down by lowering the voltage of the voltage divider node.

3. The standing wave protection circuit according to claim 2, characterized in that, The voltage divider circuit includes a first resistor and a second resistor connected sequentially between the voltage terminal and the ground terminal, and the common node of the first resistor and the second resistor is the voltage divider node; The pull-down circuit includes a third resistor, a fourth resistor, and a transistor connected sequentially between the bias terminal and the ground terminal of the power amplifier circuit. The common node of the third resistor and the fourth resistor is connected to the voltage divider node, and the base of the transistor is connected to the output terminal of the threshold detection circuit.

4. The standing wave protection circuit according to claim 3, characterized in that, The threshold detection circuit has a first input terminal, a second input terminal, a first output terminal, and a second output terminal. Its second input terminal is connected to the output terminal of the detector amplifier circuit, its first output terminal is connected to the base of the transistor, and its first input terminal is connected to its second output terminal.

5. The standing wave protection circuit according to claim 1, characterized in that, The attenuation circuit includes: The fifth resistor has its first end connected to the output terminal of the reflected power and its second end connected to the first capacitor. The sixth resistor is connected between the first end of the fifth resistor and the ground terminal; The seventh resistor is connected between the second end of the fifth resistor and the ground terminal.

6. The standing wave protection circuit according to claim 1, characterized in that, The detector amplification circuit includes: The detector's input pin is connected to the output of the attenuation circuit via the first capacitor; An amplifier circuit, with its input terminal connected to the output pin of the detector and its output terminal connected to the input terminal of the output power control circuit.

7. The standing wave protection circuit according to claim 6, characterized in that, The amplifier circuit includes an operational amplifier, an eighth resistor, and a ninth resistor. The non-inverting input of the operational amplifier is connected to the output pin of the detector. The output of the operational amplifier is connected to the ground terminal via the eighth and ninth resistors. The inverting input of the operational amplifier is connected to the common node of the eighth and ninth resistors.

8. The standing wave protection circuit according to claim 6, characterized in that, The detector amplification circuit also includes: The first filter circuit is connected between the output pin of the detector and the input terminal of the amplifier circuit. The second filter circuit is connected between the power supply terminal and the power supply pin of the detector.

9. The standing wave protection circuit according to claim 8, characterized in that, The first filter circuit includes a tenth resistor and a second capacitor. The first end of the tenth resistor is connected to the output pin of the detector, the second end of the tenth resistor is connected to the input terminal of the amplifier circuit, and the second capacitor is connected between the second end of the tenth resistor and the ground terminal. The second filter circuit includes an inductor connected between the power supply terminal and the power supply pin of the detector, a third capacitor connected between the power supply terminal and the ground terminal, and a fourth capacitor connected between the power supply terminal and the ground terminal.

10. A radio frequency power amplifier, characterized in that, include: The power amplifier circuit includes a pre-drive amplifier, a drive amplifier, and a final stage amplifier connected sequentially between the RF input terminal and the RF output terminal. A coupler is disposed between the power amplifier and the radio frequency output terminal. A load is connected between its first output terminal and the ground terminal. Its first output terminal outputs positive power, and its second output terminal outputs reflected power. as well as The standing wave protection circuit as described in any one of claims 1-9, wherein the standing wave protection circuit is connected between the second output terminal of the coupler and the bias terminal of the pre-drive amplifier.

Images