High-efficiency bidirectional amplifier

Abstract

The high-efficiency bidirectional amplifier comprises a first switch module, a power amplifier, a second switch module and a low-noise amplifier, the second switch module comprises a first radio frequency switch tube and a second radio frequency switch tube, and a source electrode of the first radio frequency switch tube is connected with a matching capacitor in series to be grounded. The state of the first radio frequency switch tube is controlled by a control voltage accessed by a grid electrode of the first radio frequency switch tube, and the first radio frequency switch tube is used for being controlled by the control voltage to be equivalent to an off-state capacitor when the bidirectional amplifier works in an emission mode, and cooperating with an output matching network of the power amplifier; and matching the target matching impedance of the output matching network to 50 ohms. The first radio frequency switch tube is regarded as a part of an output matching network of the power amplifier, the matching network is realized by using the off-state capacitance of the first radio frequency switch tube, and the original matching network is omitted, so that the insertion loss of the output matching network is reduced, and the efficiency of the power amplifier is improved.

Description

Technical Field

[0001] This utility model relates to the field of amplifier technology, specifically to a high-efficiency bidirectional amplifier. Background Technology

[0002] A bidirectional amplifier is an integrated radio frequency (RF) module that combines transmit and receive functions. It typically includes a series of RF circuits for handling signal transmission, reception, switching, amplification, and filtering. Transmission primarily utilizes a power amplifier to efficiently amplify the signal, ensuring it is within the target frequency band and has sufficient power output. Reception mainly uses a low-noise amplifier to improve the received signal strength while minimizing noise generation, ensuring the reception of even weak signals. In practice, transmission and reception are usually time-division multiplexing, requiring an RF switch to switch between them. This ensures that the transmitted signal does not directly enter the receiving channel to avoid damaging the low-noise amplifier. Existing bidirectional amplifiers often match the inputs of the RF switch and the power amplifier to 50 ohms before cascading. This design method results in relatively high insertion loss for the overall bidirectional amplifier, hindering high efficiency. Utility Model Content

[0003] The purpose of this invention is to provide a high-efficiency bidirectional amplifier that treats the first RF switch as part of the power amplifier output matching network and utilizes the off-state capacitor of the first RF switch to realize the matching network, thereby simplifying the original matching network, reducing the insertion loss of the output matching network, and improving the efficiency of the power amplifier.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following solution:

[0005] A high-efficiency bidirectional amplifier includes a first switching module, a power amplifier, a second switching module, and a low-noise amplifier. The second switching module includes a first radio frequency (RF) switch connected in parallel with the output of the power amplifier and a second RF switch connected in parallel with the input of the low-noise amplifier. The source of the first RF switch is connected in series with a matching capacitor and grounded. The state of the first RF switch is controlled by a control voltage connected to its gate. When the bidirectional amplifier is operating in transmit mode, the first RF switch is equivalent to an off-state capacitor under the control voltage, working in conjunction with the output matching network of the power amplifier to match the target matching impedance of the output matching network to 50 ohms.

[0006] In a specific implementation, the power amplifier includes a cascaded pre-amplifier PA, a final stage PA_FET, and an output matching network, as well as a drain bias circuit connected to the drain of the final stage PA_FET.

[0007] In some specific implementations, the output matching network includes a first matching microstrip line MLIN1, a second matching microstrip line MLIN2, and a DC blocking capacitor Cdc connected in series. One end of the first matching microstrip line MLIN1 is connected to the drain of the final stage PA_FET. The drain bias circuit is connected in parallel between the first matching microstrip line MLIN1 and the second matching microstrip line MLIN2. One end of the DC blocking capacitor Cdc is connected to the input terminal of the first RF switch.

[0008] In a specific implementation, the drain bias circuit includes a series RF choke and a drain power supply. One end of the RF choke is connected in parallel between the first matching microstrip line MLIN1 and the second matching microstrip line MLIN2, and the other end is connected to the drain power supply.

[0009] In a specific implementation, the second switching module further includes a third matching microstrip line MLIN3 and a fourth matching microstrip line MLIN4. The two ends of the third matching microstrip line MLIN3 are connected to one end of the DC blocking capacitor Cdc and one end of the fourth matching microstrip line MLIN4, respectively. The other end of the fourth matching microstrip line MLIN4 is connected to the input terminal of the low noise amplifier. The drain of the second RF switch is connected in parallel between the low noise amplifier and the fourth matching microstrip line MLIN4.

[0010] In a specific implementation scheme, the input terminal of the first switch module is connected to the signal transmission input / reception output terminal, and the output terminal of the second switch module is connected to the signal transmission output / reception input terminal through a capacitor.

[0011] In the specific implementation plan, the first switching module adopts an RF single-pole double-throw switch.

[0012] The beneficial effects of this utility model are:

[0013] This invention connects a matching capacitor in series with the source of the first RF switch. When the bidirectional amplifier is in transmit mode, the first RF switch is in the off state. The first RF switch is equivalent to an off-state capacitor connected in series with the switch matching capacitor, replacing the existing output matching capacitor C1 in the power amplifier module output matching network. This makes the target matching impedance of the output matching network non-50 ohms. The off-state capacitor of the first RF switch participates in the matching. The switching section and the power amplifier section are designed in a coordinated manner, reducing the loss of the bidirectional amplifier output matching network to improve the efficiency in the transmit state, and making the circuit more compact and reducing the chip area. Attached Figure Description

[0014] Figure 1 A schematic diagram of the matching output of an existing conventional bidirectional amplifier;

[0015] Figure 2 A schematic diagram of the bidirectional amplifier structure provided in this embodiment of the utility model;

[0016] Figure 3 The equivalent circuit diagram of the first switching transistor of the bidirectional amplifier when it is operating in transmit mode, as provided in the embodiment of this utility model. Detailed Implementation

[0017] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the implementation of the present invention is not limited thereto.

[0018] In the description of this utility model, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "longitudinal", "lateral", "horizontal", "inner", "outer", "front", "rear", "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the utility model product is in use. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0019] In the description of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set up," "have," "install," "connect," and "connect" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0020] Existing, such as Figure 1 As shown, the bidirectional amplifier includes two transmit / receive switching switches, a power amplifier, an output matching network, and a low-noise amplifier. The bidirectional amplifier operates in two modes:

[0021] (1) Launch mode

[0022] Provides a transmission path to amplify low-power radio frequency signals (such as radar signals) to the power level required by the system. Efficient signal amplification is achieved through a power amplifier (PA). Ensures the transmitted signal is within the target frequency band and has sufficient radio frequency power output.

[0023] (2) Receiving mode

[0024] It receives target echoes or communication signals, amplifies and filters them for subsequent processing. It enhances the received signal strength using a low-noise amplifier (LNA) while minimizing noise. It provides high sensitivity to ensure the reception of even weak signals.

[0025] These two operating modes are typically switched between the transmit and receive paths using an RF switch or duplexer. In practical applications, transmission and reception are usually time-division multiplexing, thus requiring the RF switch to switch between them. This ensures that the transmitted signal does not directly enter the receive channel to avoid damaging the low-noise amplifier.

[0026] To match the output of the power amplifier to 50 ohms, a traditional circuit topology such as Figure 1 As shown, the output matching network uses microstrip lines and capacitors for matching, including the matching microstrip lines (MLIN1, MLIN2), the DC blocking capacitor Cdc and the grounding capacitor C1 connected in parallel. First, the power amplifier is matched to 50 ohms through the output matching network, and then the second transmit / receive switching section is matched to 50 ohms. This design method results in a high overall insertion loss after combination, which is not conducive to the realization of high efficiency and consumes more area.

[0027] To address the above problems, the present invention will be described in detail below with reference to the accompanying drawings and embodiments:

[0028] Example 1:

[0029] like Figures 2 to 3 As shown, this embodiment provides a high-efficiency bidirectional amplifier, including a first switching module, a power amplifier, a second switching module, and a low-noise amplifier (LNA). The second switching module includes a first RF switch SW_FET 1 connected in parallel with the output terminal of the power amplifier and a second RF switch SW_FET 2 connected in parallel with the input terminal of the low-noise amplifier. The source of the first RF switch SW_FET 1 is connected in series with a matching capacitor Cs1 and grounded. The state of the first RF switch SW_FET 1 is controlled by the control voltage connected to its gate. The state of the second RF switch SW_FET 2 is controlled by the control voltage connected to its gate. When the bidirectional amplifier is operating in transmit mode, the first RF switch SW_FET 1 is controlled by the control voltage and is equivalent to an off-state capacitor Coff, working in conjunction with the output matching network of the power amplifier to match the target matching impedance of the output matching network to 50 ohms.

[0030] The second switching module also includes a third matching microstrip line MLIN3 and a fourth matching microstrip line MLIN4. The two ends of the third matching microstrip line MLIN3 are connected to one end of the DC blocking capacitor Cdc and one end of the fourth matching microstrip line MLIN4, respectively. The other end of the fourth matching microstrip line MLIN4 is connected to the input terminal of the low-noise amplifier (LNA). The drain of the second RF switch SW_FET 2 is connected in parallel between the LNA and the fourth matching microstrip line MLIN4. The input terminal of the first switching module is connected to the signal transmit input / receive output terminal, and the output terminal of the second switching module is connected to the signal transmit output / receive input terminal through the capacitor Cdc. That is, the third matching microstrip line MLIN3 and the fourth matching microstrip line MLIN4 are connected in parallel with the capacitor Cdc before reaching the signal transmit output / receive input terminal.

[0031] Specifically, the first switching module uses an RF single-pole double-throw switch SW. The moving contact of the RF single-pole double-throw switch SW is connected to the signal transmission input / reception output terminal, and the two stationary contacts of the single-pole double-throw switch SW are respectively connected to the input terminal of the pre-amplifier PA and the output terminal of the low-noise amplifier LNA. The first switching module is used to switch the bidirectional amplifier to different operating modes, including transmission mode and reception mode.

[0032] More specifically, the power amplifier includes a cascaded preamplifier PA, a final stage PA_FET and an output matching network, as well as a drain bias circuit connected to the drain of the final stage PA_FET.

[0033] In this embodiment, the output matching network removes the ground capacitor C1 from the traditional design. Instead, it utilizes the off-state capacitor of the first RF switch SW_FET 1 to achieve a similar function to C1. The target matching impedance of the output matching network becomes non-50 ohms. The off-state capacitor of SW_FET 1 participates in the matching, and the switching section and power amplifier section are designed collaboratively. The output matching network includes a first matching microstrip line MLIN1, a second matching microstrip line MLIN2, and a DC blocking capacitor Cdc connected in series. One end of the first matching microstrip line MLIN1 is connected to the drain of the final stage PA_FET. A drain bias circuit is connected in parallel between the first matching microstrip line MLIN1 and the second matching microstrip line MLIN2. One end of the DC blocking capacitor Cdc is connected to the drain of the first RF switch SW_FET 1.

[0034] In a specific implementation, the drain bias circuit includes a series-connected RF choke and a drain power supply Vdrain. One end of the RF choke is connected in parallel between the first matching microstrip line MLIN1 and the second matching microstrip line MLIN2, and the other end is connected in series with the gate controller to ground.

[0035] It can be understood that the first switching transistor SW_FET 1 is a radio frequency (RF) switch based on a field-effect transistor (FET). At this time, the two states of the transistor in the RF switch can be modeled by the following equivalent circuits:

[0036] (1) Conductive state (ON state)

[0037] Equivalent model: When the transistor is in the conductive state, it behaves as a low series resistance Ron. Ron is the on-state impedance of the transistor when it is conducting. Ron is determined by the on-resistance of the transistor and depends on the material, size, and process parameters of the transistor.

[0038] (2) Cut-off state (OFF state)

[0039] Equivalent model: When the transistor is in the cut-off state, it behaves as a high impedance and has a parasitic capacitance (Coff). Coff is the parasitic capacitance of the transistor in the cut-off state (usually caused by the junction capacitance inside the transistor structure). Coff is determined by the parasitic junction capacitance between the source, drain, and gate of the transistor. Generally, the smaller the transistor size, the smaller Coff is.

[0040] The control mechanism of the first RF switching transistor SW_FET 1 is: The switching state of the transistor is controlled by the gate voltage (Vgs). When Vgs > Vth (threshold voltage): the transistor conducts, corresponding to the Ron state. When Vgs < Vth: the transistor is cut off, corresponding to the Coff state.

[0041] Based on the above principle, the working principle of the high-efficiency bidirectional amplifier in this embodiment is as follows:

[0042] When the bidirectional amplifier switches to the transmit mode, the single-pole double-throw switch SW switches to the transmit channel. The transmit channel includes a power amplifier. The RF signal is input from the transmit input / receive output, passes through the single-pole double-throw switch, and is input into the power amplifier. At this time, in order to improve the efficiency of the transmit channel, a control voltage less than the threshold voltage of the first RF switching transistor SW_FET 1 is input to the gate of the first RF switching transistor SW_FET 1, so that the first RF switching transistor SW_FET 1 is in the cut-off state. At this time, the first RF switching transistor SW_FET 1 is equivalent to the off-state capacitance Coff. As Figure 3 shown, by connecting the off-state capacitance Coff in series with the source matching capacitance Cs1, it assists the output matching network to match the target matching impedance to 50 ohms. In this design method, the off-state capacitance Coff of the switch part is used to replace the output matching capacitance C1 in the traditional design method, reducing the number of components used, reducing the overall loss, and improving the efficiency of the bidirectional amplifier.

[0043] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of this utility model, and the utility model is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of this utility model, and these modifications and improvements are also considered to be within the protection scope of this utility model.

Claims

1. A high efficiency bidirectional amplifier comprising a first switching module, a power amplifier, a second switching module and a low noise amplifier, characterized in that, The second switch module comprises a first radio frequency switch tube connected in parallel with the output end of the power amplifier and a second radio frequency switch tube connected in parallel with the input end of the low noise amplifier, the source of the first radio frequency switch tube is connected in series with a matching capacitor and grounded, and the state of the first radio frequency switch tube is controlled by a control voltage input to the gate of the first radio frequency switch tube, and the first radio frequency switch tube is equivalent to a closed state capacitor controlled by the control voltage when the bidirectional amplifier works in the transmitting mode, and cooperates with the output matching network of the power amplifier to match the target matching impedance of the output matching network to 50 ohms.

2. A high efficiency bidirectional amplifier as claimed in claim 1, characterized in that The power amplifier comprises a front-stage power amplifier PA, a final-stage PA_FET and an output matching network connected in cascade, and a drain bias circuit connected to the drain of the final-stage PA_FET.

3. A high efficiency bidirectional amplifier as claimed in claim 2, characterized in that The output matching network comprises a first matching microstrip line MLIN1, a second matching microstrip line MLIN2 and a direct current blocking capacitor Cdc connected in series, one end of the first matching microstrip line MLIN1 is connected to the drain of the final-stage PA_FET, the drain bias circuit is connected in parallel between the first matching microstrip line MLIN1 and the second matching microstrip line MLIN2, and one end of the direct current blocking capacitor Cdc is connected to the input end of the first radio frequency switch tube.

4. A high efficiency bilateral amplifier as claimed in claim 3, characterized in that The drain bias circuit comprises a radio frequency choke and a drain power supply connected in series, one end of the radio frequency choke is connected in parallel between the first matching microstrip line MLIN1 and the second matching microstrip line MLIN2, and the other end is connected to the drain power supply.

5. A high efficiency bilateral amplifier as claimed in claim 3, characterized in that The second switch module further comprises a third matching microstrip line MLIN3 and a fourth matching microstrip line MLIN4, two ends of the third matching microstrip line MLIN3 are respectively connected to one end of the direct current blocking capacitor Cdc and one end of the fourth matching microstrip line MLIN4, the other end of the fourth matching microstrip line MLIN4 is connected to the input end of the low noise amplifier, and the drain of the second radio frequency switch tube is connected in parallel between the low noise amplifier and the fourth matching microstrip line MLIN4.

6. A high efficiency bilateral amplifier as claimed in claim 5, characterised in that, The input end of the first switch module is connected to a signal transmitting input / receiving output end, and the output end of the second switch module is connected to the signal transmitting output / receiving input end through a capacitor.

7. A high efficiency bilateral amplifier as claimed in claim 5, characterized in that The first switch module adopts a radio frequency single-pole double-throw switch.

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