CN211656144U

CN211656144U - TDD communication equipment

Info

Publication number: CN211656144U
Application number: CN202020532176.2U
Authority: CN
Inventors: 肖世彬; 李勇军; 周金龙
Original assignee: Shenzhen Guoren Wireless Communication Co Ltd
Current assignee: Shenzhen Guoren Wireless Communication Co Ltd
Priority date: 2020-04-10
Filing date: 2020-04-10
Publication date: 2020-10-09
Anticipated expiration: 2030-04-10

Abstract

The utility model relates to a TDD communication equipment, including TX link, RX link, radio frequency switch, TX power, TX synchronizing signal output circuit, RX power and RX synchronizing signal output circuit, the TX link is including the TX drive amplification module and the power amplification module that concatenate together, the RX link is including low noise amplification module and RX drive amplification module that concatenate together, radio frequency switch connects between power amplification module, low noise amplification module and the antenna interface, still include TX power switch circuit and RX power switch circuit, TX power switch circuit connects between TX power and TX drive amplification module and with radio frequency switch connects, RX power switch circuit connects between RX power and RX drive amplification module, low noise amplification module and with radio frequency switch connects. The utility model discloses can realize the isolation of signal between TX link and the RX link, the isolation is high.

Description

TDD communication equipment

[ technical field ] A method for producing a semiconductor device

The utility model relates to a mobile communication field, it relates to a TDD (Time division duplex) communication equipment specifically.

[ background of the invention ]

TDD communication devices use Time Division Multiple Access (TDMA) technology, where TX (transmit) and RX (receive) links operate at the same frequency and operate in a time-division manner through radio frequency switches. When the TX link is in an operating state, the rf signal output by the TX link leaks to the RX link through the rf switch, and the leaked signal is absorbed after entering the RX link, which may cause the communication device to fail to operate normally; when the RX link is in an operating state, a bottom noise signal of the TX link leaks to the RX link through the rf switch, and the leaked signal is superimposed with a signal received by the antenna at the mobile terminal, and is absorbed after entering the RX link, which may cause deterioration of the communication equipment and even abnormal operation.

Accordingly, there is a need for an improved TDD communications device.

[ Utility model ] content

An object of the utility model is to overcome the not enough of above-mentioned technique, provide a TDD communication equipment, can realize the isolation of signal between TX link and the RX link, the isolation is high, and the reliability is high.

The utility model provides a pair of TDD communication equipment, including TX link, RX link, radio frequency switch, TX power, TX synchronizing signal output circuit, RX power and RX synchronizing signal output circuit, the TX link is including the TX drive amplifier module and the power amplification module that concatenate together, the RX link is including low noise amplifier module and RX drive amplifier module that concatenate together, radio frequency switch connects between power amplification module, low noise amplifier module and antenna interface, still include TX power switch circuit and RX power switch circuit, TX power switch circuit connects between TX power and TX drive amplifier module and with radio frequency switch connects, TX synchronizing signal output circuit connects between TX power switch circuit and radio frequency switch, RX power switch circuit connects RX power and RX drive amplifier module, The low-noise amplification module is connected with the radio frequency switch, and the RX synchronous signal output circuit is connected between the RX power switch circuit and the radio frequency switch;

when a TX synchronous signal output by the TX synchronous signal output circuit is positioned at a wave crest of a pulse period and an RX synchronous signal output by the RX synchronous signal output circuit is positioned at a wave trough of the pulse period, the radio frequency switch is connected between the power amplification module and an antenna interface, the TX power switch circuit is connected between the TX power supply and the TX driving amplification module, and the RX power switch circuit is disconnected between the RX power supply and the RX driving amplification module as well as the low-noise amplification module;

when the TX synchronous signal output by the TX synchronous signal output circuit is positioned at the wave trough of a pulse period and the RX synchronous signal output by the RX synchronous signal output circuit is positioned at the wave crest of the pulse period, the radio frequency switch is connected between the low-noise amplification module and the antenna interface, the TX power switch circuit is disconnected between the TX power supply and the TX driving amplification module, and the RX power switch circuit is connected between the RX power supply and the RX driving amplification module as well as the low-noise amplification module.

Further, the radio frequency switch includes a first input end, a second input end and a control end, the control end includes a first port, a second port and a third port, the first port is connected with the antenna interface, the second port is connected with the output end of the power amplification module, and the third port is connected with the input end of the low noise amplification module.

Further, the TX power switch circuit includes a first NPN transistor and a first PMOS transistor connected in series, where the first NPN transistor is connected to the first input terminal, and the first PMOS transistor is connected between the TX power and the power supply terminal of the TX driving and amplifying module.

Further, the first NPN transistor has a first base B and a first collector C, the first PMOS transistor has a first gate G, a first source S, and a first drain D, the first base B is connected to the first input terminal, the TX synchronization signal output circuit is connected between the first base B and the first input terminal, the first collector C is connected to the first gate G, the first source S is connected to the TX power supply, and the first drain D is connected to a power supply terminal of the TX driving amplification module.

Further, when the TX synchronous signal output by the TX synchronous signal output circuit is located at a peak of a pulse period and the RX synchronous signal output by the RX synchronous signal output circuit is located at a trough of the pulse period, the first port and the second port of the radio frequency switch are turned on to achieve connection between the output end of the power amplification module and the antenna interface, the first base B is at a high level and the first NPN transistor is in saturation conduction, the first gate G is at a low level and the first PMOS transistor is in conduction, thereby achieving connection between the TX power supply and the power supply end of the TX driving amplification module;

when the TX synchronous signal output by the TX synchronous signal output circuit is located at a trough of a pulse cycle and the RX synchronous signal output by the RX synchronous signal output circuit is located at a peak of the pulse cycle, the first port and the third port of the radio frequency switch are turned on to realize the connection between the input end of the low noise amplification module and the antenna interface, the first base B is at a low level and the first NPN transistor is turned off, and the first gate G is at a high level and the first PMOS transistor is turned off to realize the disconnection between the TX power supply and the power supply end of the TX driving amplification module.

Further, the first NPN transistor also has a first emitter E, which is grounded.

Further, the RX power switch circuit includes a second NPN transistor and a second PMOS transistor connected in series, where the second NPN transistor is connected to the second input terminal, and the second PMOS transistor is connected between the RX power supply and the power supply terminal of the RX driving and amplifying module and the power supply terminal of the low noise amplifying module.

Further, the second NPN transistor has a second base B and a second collector C, the second PMOS transistor has a second gate G, a second source S, and a second drain D, the second base B is connected to the second input terminal, the RX synchronous signal output circuit is connected between the second base B and the second input terminal, the second collector C is connected to the second gate G, the second source S is connected to the RX power supply, and the second drain D is respectively connected to the power supply terminal of the RX driving amplification module and the power supply terminal of the low noise amplification module.

Further, when the TX synchronous signal output by the TX synchronous signal output circuit is located at a peak of a pulse period and the RX synchronous signal output by the RX synchronous signal output circuit is located at a trough of the pulse period, the first port and the second port of the radio frequency switch are turned on to achieve connection between the output end of the power amplification module and the antenna interface, the second base B is at a low level and the second NPN transistor is turned off, the second gate G is at a high level and the second PMOS transistor is turned off, thereby achieving disconnection between the RX power supply and the power supply end of the RX driving amplification module and the power supply end of the low noise amplification module;

when the TX synchronous signal output by the TX synchronous signal output circuit is located at a trough of a pulse cycle and the RX synchronous signal output by the RX synchronous signal output circuit is located at a peak of the pulse cycle, the first port and the third port of the radio frequency switch are switched on to realize switching on the connection between the input end of the low noise amplification module and the antenna interface, the second base B is at a high level and the second NPN transistor is in saturated conduction, the second gate G is at a low level and the second PMOS transistor is in conduction, so as to realize switching on the connection between the RX power supply and the power end of the RX driving amplification module and the power end of the low noise amplification module.

Further, the second NPN transistor also has a second emitter E, which is grounded.

The utility model discloses a set up TX power switch circuit and RX power switch circuit, when the TX link is in operating condition, the radio frequency signal of TX link output can not leak to RX link through the radio frequency switch to realize the isolation of signal between TX link and RX link; when RX is in working state, the bottom noise signal of TX chain circuit will not leak to RX chain circuit through radio frequency switch, thus realizing the isolation of signal between TX chain circuit and RX chain circuit, the isolation is high, ensuring the normal work of communication equipment, and the reliability is high.

[ description of the drawings ]

Fig. 1 is a block diagram of a TDD communications device according to an embodiment of the present invention;

fig. 2 is a schematic diagram of the TX link of the TDD communications device shown in fig. 1 in an operating state;

fig. 3 is a schematic diagram of the RX link of the TDD communications device of fig. 1 in an operating state;

fig. 4 is a waveform diagram of a TX synchronization signal and an RX synchronization signal of the TDD communication device shown in fig. 1.

[ detailed description ] embodiments

The invention is further described with reference to the following figures and examples.

Referring to fig. 1, the present invention provides a TDD communications device, including a TX link, an RX link, a radio frequency switch 30, a TX power supply 40, a TX synchronization signal output circuit 71, an RX power supply 50, an RX synchronization signal output circuit 72, a TX power switch circuit 80, and an RX power switch circuit 90.

The TX link comprises a TX driving amplification block 11 and a power amplification block 12 connected together in series. The RX chain comprises a low noise amplification module 22 and an RX drive amplification module 21 connected together in series.

The rf switch 30 is connected between the power amplification module 12, the low noise amplification module 22, and the antenna interface 60. The rf switch 30 is used to switch the operation status of the TX link and the RX link. The antenna interface 60 is used to connect with an antenna. When the TX link is in a working state, the rf signal output by the TX link is output to the antenna interface 60 through the rf switch 30, and then output to the antenna through the antenna interface 60. When the RX link is in an operating state, the radio frequency signal received by the antenna is output to the RX link through the antenna interface 60 and the radio frequency switch 30, and then output to the base station through the RX link.

The TX power supply 40 is used to supply power to the TX driving amplification module 11. The RX power supply 50 is used to provide power to the RX driving amplification module 21 and the low noise amplification module 22.

The TX power switch circuit 80 is connected between the TX power source 40 and the TX driving amplification module 11 and to the rf switch 30, and the TX synchronizing signal output circuit 71 is connected between the TX power switch circuit 80 and the rf switch 30. The RX power switch circuit 90 is connected between the RX power supply 50 and the RX driving amplification module 21 and the low noise amplification module 22, and is connected to the rf switch 30, and the RX synchronous signal output circuit 72 is connected between the RX power switch circuit 90 and the rf switch 30.

The TX synchronization signal output circuit 71 and the RX synchronization signal output circuit 72 are respectively used for connecting with the base station subsystem and respectively outputting a TX synchronization signal and an RX synchronization signal. The TX sync signal and the RX sync signal are both pulse signals and are synchronous, and their waveforms are shown in fig. 4, where when the TX sync signal is located at the peak of the pulse period, the TX sync signal is a high level signal, and the RX sync signal is correspondingly located at the trough of the pulse period, and the RX sync signal is a low level signal. When the TX synchronization signal is located at the wave valley of the pulse period, the TX synchronization signal is a low level signal, and the RX synchronization signal is correspondingly located at the wave peak of the pulse period, and the RX synchronization signal is a high level signal.

In this embodiment, a period T1 is defined when the TX sync signal is located at the peak of the pulse period and the RX sync signal is located at the valley of the pulse period, and a period T2 is defined when the TX sync signal is located at the valley of the pulse period and the RX sync signal is located at the peak of the pulse period.

When the TX sync signal and the RX sync signal are located at the T1 period of the pulse cycle, the radio frequency switch 30 turns on the connection between the power amplification module 12 and the antenna interface 60, so that the TX link is in a working state, the TX power switch circuit 80 switches on the connection between the TX power 40 and the TX driving and amplifying module 11, the TX driving and amplifying module 11 can work normally when supplying power, so that the TX link can work normally, the RX power switch circuit 90 disconnects the RX power 50 from the RX driving and amplifying module 21 and the low noise amplifying module 22, at this time, the RX driving and amplifying module 21 and the low noise amplifying module 22 are powered off, so that the RX link and the rf switch 30 cannot form a path, the rf signal output from the TX link does not leak to the RX link through the rf switch 30, therefore, the isolation of signals between the TX link and the RX link is realized, the isolation degree is high, and the normal work of the communication equipment is ensured.

When the TX synchronous signal and the RX synchronous signal are in a period T2 of the pulse cycle, the radio frequency switch 30 turns on the connection between the low noise amplification module 22 and the antenna interface 60, so that the RX link is in an operating state, the TX power switch circuit 80 turns off the connection between the TX power source 40 and the TX driving amplification module 11, the TX driving amplification module 11 is powered off, the RX power switch circuit 90 turns on the connection between the RX power source 50 and the RX driving amplification module 21 and the low noise amplification module 22, the RX driving amplification module 21 and the low noise amplification module 22 are powered on normally and can operate normally, so that the RX link can operate normally, at this time, because the TX driving amplification module 11 is powered off, the TX link and the radio frequency switch 30 cannot form a path, and therefore, the bottom noise signal of the TX link cannot leak to the RX link through the radio frequency switch 30, thereby realizing the isolation of the signals between the TX link and the RX link, the isolation is high, and the normal work of the communication equipment is ensured.

The utility model discloses a set up TX power switch circuit 80 and RX power switch circuit 90, make the TX link be in operating condition when connecting between power amplification module 12 and antenna interface 60 and switch on the connection between TX power 40 and TX drive amplification module 11 and break off the connection between RX power 50 and RX drive amplification module 21, low noise amplification module 22 at the same time at radio frequency switch 30 switch-on power amplification module 12, can make TX drive amplification module 11 can normally work and make RX drive amplification module 21, low noise amplification module 22 outage, thereby RX link and radio frequency switch 30 can not form the route, therefore the radio frequency signal of TX link output can not leak to the RX link through radio frequency switch 30, thereby realize the isolation of signal between TX link and the RX link; when the radio frequency switch 30 is connected between the low noise amplification module 22 and the antenna interface 60, so that the RX link is in an operating state, the connection between the TX power supply 40 and the TX driving amplification module 11 is disconnected, and the connection between the RX power supply 50 and the RX driving amplification module 21 and the low noise amplification module 22 is connected, so that the RX driving amplification module 21 and the low noise amplification module 22 can normally operate and the TX driving amplification module 11 is powered off, and therefore, the TX link and the radio frequency switch 30 do not form a path, and therefore, a bottom noise signal of the TX link does not leak to the RX link through the radio frequency switch 30, so that signal isolation between the TX link and the RX link is realized, the isolation degree is high, normal operation of the communication device is ensured, and the reliability is high.

Referring to fig. 2 and fig. 3, in this embodiment, specifically, the rf switch 30 includes a first input terminal, a second input terminal, and a control terminal, the control terminal includes a first port 31, a second port 32, and a third port 33, and the first port 31 is connected to the antenna interface 60. The second port 32 is connected to the output terminal of the power amplification module 12, and the third port 33 is connected to the input terminal of the low noise amplification module 22.

The TX power switching circuit 80 includes a first NPN transistor (NPN type double junction transistor) Q1 and a first PMOS (P type MOSFET, P type metal oxide semiconductor field effect transistor) Q2 connected in series. The first NPN transistor Q1 is connected to the first input terminal, and the first PMOS transistor Q2 is connected between the TX power supply 40 and the power supply terminal of the TX driving amplifying module 11. The TX synchronization signal output circuit 71 is connected between the first NPN transistor Q1 and the first input terminal.

Further, the first NPN transistor Q1 has a first base B, a first collector C, and a first emitter E. The first emitter E is grounded. The first PMOS transistor Q2 has a first gate G, a first source S and a first drain D. The first base B is connected to the first input terminal, the TX synchronization signal output circuit 71 is connected between the first base B and the first input terminal, the first collector C is connected to the first gate G, the first source S is connected to the TX power source 40, and the first drain D is connected to the power terminal of the TX driving and amplifying module 11.

The RX power switch circuit 90 includes a second NPN transistor Q3 and a second PMOS transistor Q4 connected in series. The second NPN transistor Q3 is connected to the second input terminal, and the second PMOS transistor Q4 is connected between the RX power supply 50 and the power supply terminals of the RX driving amplifying module 21 and the low noise amplifying module 22. The RX synchronization signal output circuit 72 is connected between the second NPN transistor Q3 and the second input terminal.

Further, a second NPN transistor Q3 has a second base B, a second collector C, and a second emitter E. The second emitter E is grounded. The second PMOS transistor Q4 has a second gate G, a second source S and a second drain D. The second base B is connected to the second input terminal, the RX synchronous signal output circuit 72 is connected between the second base B and the second input terminal, the second collector C is connected to the second gate G, the second source S is connected to the RX power supply 50, and the second drain D is connected to the power supply terminal of the RX driving amplification module 21 and the power supply terminal of the low noise amplification module 22, respectively.

When the TX synchronization signal output by the TX synchronization signal output circuit 71 is located at the peak of the pulse cycle and the RX synchronization signal output by the RX synchronization signal output circuit 72 is located at the valley of the pulse cycle, that is, when the TX synchronization signal and the RX synchronization signal are located at the T1 period of the pulse cycle, as shown in fig. 4, since the output TX synchronization signal is a high level signal and the RX synchronization signal is a low level signal, the first port 31 and the second port 32 of the rf switch 30 are turned on at this time to turn on the connection between the output terminal of the power amplification module 12 and the antenna interface 60, as shown in fig. 2, so that the TX link is in an operating state. And since the output TX synchronous signal is a high level signal, the first base B is high and the first NPN transistor Q1 is turned on in saturation. Since the first base B is at a high level, the first gate G is pulled low to a low level, and thus the first gate G is at a low level and the first PMOS transistor Q2 is turned on, so that connection between the TX power source 40 and the power source terminal of the TX driving and amplifying module 11 is turned on, and the TX driving and amplifying module 11 can normally work when power is supplied, so that the TX link can normally work. Since the output RX synchronous signal is a low level signal, the second base B is low and the second NPN transistor Q3 is turned off. The second base electrode B is at a low level, so that the second gate electrode G is pulled up to a high level, the second gate electrode G is at a high level, and the second PMOS transistor Q4 is turned off, thereby disconnecting the connection between the RX power supply 50 and the power supply end of the RX driving amplification module 21 and the power supply end of the low noise amplification module 22, and disconnecting the RX driving amplification module 21 and the low noise amplification module 22, so that the RX link and the radio frequency switch 30 do not form a path, at this time, the radio frequency signal output by the TX link does not leak to the RX link through the radio frequency switch 30, thereby realizing the isolation of the signal between the TX link and the RX link, having a high isolation degree, and ensuring the normal operation of the NPN TDD communication device, and the TX power switch circuit 80 and the RX power switch circuit 90 both adopt transistors and PMOS transistors, and have a simple structure, a low cost, do not occupy a PCB space.

When the TX synchronization signal output by the TX synchronization signal output circuit 71 is located at the trough of the pulse cycle and the RX synchronization signal output by the RX synchronization signal output circuit 72 is located at the peak of the pulse cycle, that is, when the TX synchronization signal and the RX synchronization signal are located at the T2 period of the pulse cycle, as shown in fig. 4, since the output TX synchronization signal is a low level signal and the RX synchronization signal is a high level signal, the first port 31 and the third port 33 of the rf switch 30 are turned on at this time to turn on the connection between the input terminal of the low noise amplification module 22 and the antenna interface 60, as shown in fig. 3, so that the RX link is in an operating state. And since the output RX synchronous signal is a high level signal, the second base B is high level and the second NPN transistor Q3 is turned on in saturation. Since the second base B is at a high level, the second gate G is pulled down to a low level, and thus the second gate G is at a low level and the second PMOS transistor Q4 is turned on, so that connection between the RX power source 50 and the power source terminal of the RX driving amplification module 21 and the power source terminal of the low noise amplification module 22 is turned on, and the RX driving amplification module 21 and the low noise amplification module 22 can normally work when power is supplied, so that the RX link can normally work. Since the output TX sync signal is a low signal, the first base B is low and the first NPN transistor Q1 is turned off. Because the first base B is at a low level, the first gate G is pulled high to a high level, the first gate G is at a high level, and the first PMOS transistor Q2 is turned off, thereby disconnecting the connection between the TX power supply 40 and the power supply terminal of the TX driving amplification module 11, and powering off the TX driving amplification module 11, so that the TX link and the radio frequency switch 30 do not form a path, at this time, a bottom noise signal of the TX link does not leak to the RX link through the radio frequency switch 30, thereby achieving isolation of signals between the TX link and the RX link, having high isolation degree, and ensuring normal operation of the TDD communication device, the TX power switch circuit 80 and the RX power switch circuit 90 both employ NPN transistors and PMOS transistors, and have simple structure, low cost, no occupation of PCB space, and high reliability. In practical applications, when the TX driving amplifying module 11 is powered off, the power amplifying module 12 is controlled to be powered off at the same time.

In the practical application process, when the TX link is in the working state, the radio frequency signal output by the TX link does not leak to the RX link through the radio frequency switch 30, but the radio frequency signal output by the TX link is radiated to the space through the end of the microstrip line of the input pin of the power amplification module 12, and the radio frequency signal radiated to the space enters the RX link. When the RX link is in a working state, the bottom noise signal of the TX link does not leak to the RX link through the rf switch 30, but the bottom noise signal of the TX link also radiates to the space through the end of the microstrip line, and the rf signal radiated to the space enters the RX link together with the signal of the mobile terminal received by the antenna after being superimposed.

When the TX link is in an operating state, the isolation value of the signal between the TX link and the RX link can be calculated by adding the sum of the gain values of the RX driving amplification module 21 and the low noise amplification module 22 to the radiation attenuation value of the end port of the microstrip line. When the RX link is in an operating state, the isolation value of the signals between the TX link and the RX link can be calculated by adding the sum of the gain values of the TX driving amplification module 11 and the power amplification module 12 to the radiation attenuation value of the end port of the microstrip line. The calculated isolation value can reach more than 80dB compared with the traditional TDD communication equipment.

The above examples only represent preferred embodiments of the present invention, which are described in more detail and detail, but are not to be construed as limiting the scope of the present invention. It should be noted that, for those skilled in the art, without departing from the concept of the present invention, several variations and modifications can be made, such as combinations of different features in the various embodiments, which are within the scope of the present invention.

Claims

1. A TDD communications device comprising a TX link, an RX link, a radio frequency switch, a TX power supply, a TX synchronous signal output circuit, an RX power supply, and an RX synchronous signal output circuit, the TX link comprising a TX driving amplification module and a power amplification module connected together in series, the RX link comprising a low noise amplification module and an RX driving amplification module connected together in series, the radio frequency switch connected between the power amplification module, the low noise amplification module, and an antenna interface, characterized in that: the TX power switch circuit is connected between the TX power supply and the TX driving amplification module and connected with the radio frequency switch, the TX synchronous signal output circuit is connected between the TX power switch circuit and the radio frequency switch, the RX power switch circuit is connected between the RX power supply and the RX driving amplification module and the low-noise amplification module and connected with the radio frequency switch, and the RX synchronous signal output circuit is connected between the RX power switch circuit and the radio frequency switch;

2. The TDD communications device of claim 1, wherein: the radio frequency switch comprises a first input end, a second input end and a control end, the control end comprises a first port, a second port and a third port, the first port is connected with the antenna interface, the second port is connected with the output end of the power amplification module, and the third port is connected with the input end of the low-noise amplification module.

3. TDD communications device according to claim 2, characterized in that: the TX power supply switching circuit comprises a first NPN transistor and a first PMOS tube which are connected in series, the first NPN transistor is connected with the first input end, and the first PMOS tube is connected between the TX power supply and a power supply end of the TX driving amplification module.

4. TDD communications device according to claim 3, characterized in that: the first NPN transistor has a first base B and a first collector C, the first PMOS transistor has a first gate G, a first source S, and a first drain D, the first base B is connected to the first input terminal, the TX synchronous signal output circuit is connected between the first base B and the first input terminal, the first collector C is connected to the first gate G, the first source S is connected to the TX power supply, and the first drain D is connected to a power supply terminal of the TX driving amplification module.

5. The TDD communication device of claim 4, wherein: when a TX synchronous signal output by the TX synchronous signal output circuit is positioned at a wave crest of a pulse period and an RX synchronous signal output by the RX synchronous signal output circuit is positioned at a wave trough of the pulse period, a first port and a second port of the radio frequency switch are connected so as to realize connection between the output end of the power amplification module and an antenna interface, a first base electrode B is in a high level and a first NPN transistor is in saturated conduction, a first grid electrode G is in a low level and a first PMOS tube is in conduction, so that connection between a TX power supply and a power supply end of the TX driving amplification module is realized;

6. The TDD communication device of claim 4, wherein: the first NPN transistor also has a first emitter E that is grounded.

7. TDD communications device according to claim 2, characterized in that: the RX power switch circuit comprises a second NPN transistor and a second PMOS transistor connected in series, the second NPN transistor is connected to the second input terminal, and the second PMOS transistor is connected between the RX power and the power supply terminal of the RX driving amplification module and the power supply terminal of the low noise amplification module.

8. The TDD communications device of claim 7, wherein: the second NPN transistor has a second base B and a second collector C, the second PMOS transistor has a second gate G, a second source S, and a second drain D, the second base B is connected to the second input terminal, the RX synchronous signal output circuit is connected between the second base B and the second input terminal, the second collector C is connected to the second gate G, the second source S is connected to the RX power supply, and the second drain D is connected to the power supply terminal of the RX driving amplification module and the power supply terminal of the low-noise amplification module, respectively.

9. The TDD communications device of claim 8, wherein: when the TX synchronous signal output by the TX synchronous signal output circuit is located at a peak of a pulse cycle and the RX synchronous signal output by the RX synchronous signal output circuit is located at a trough of the pulse cycle, the first port and the second port of the radio frequency switch are turned on to achieve connection between the output end of the power amplification module and the antenna interface, the second base B is at a low level and the second NPN transistor is turned off, the second gate G is at a high level and the second PMOS transistor is turned off, thereby achieving disconnection between the RX power supply and the power supply end of the RX driving amplification module and the power supply end of the low noise amplification module;

10. The TDD communications device of claim 8, wherein: the second NPN transistor also has a second emitter E, which is grounded.