JP5282685B2 - TDD transceiver - Google Patents

Description

  The present invention relates to a TDD transmission / reception apparatus. The present invention relates to a TDD transmission / reception apparatus that can be applied to a transmission / reception unit such as a wireless apparatus using a TDD (Time Division Duplex) system in a mobile radio communication base station.

  The TDD scheme is one of wireless communication schemes that are useful from the viewpoint of effective use of frequency, and uses a common frequency band for transmission and reception, and switches between transmission and reception by time division within one frequency band. This method is adopted in part of WiMAX (Worldwide Interoperability for Microwave Access) and LTE (Long Term Evolution).

  The TDD transmission / reception apparatus needs to construct a transmission system and a reception system in the same frequency band in one transmission / reception apparatus. The transmission signal power wraps around the reception system during transmission and the transmission system noise during reception There is a technical problem peculiar to the TDD system, such as preventing sneaking into the receiving system.

  As an example of a conventional TDD transmission / reception apparatus, a configuration example of a transmission / reception unit (TRX) of a mobile radio base station (BS) is shown in FIG. First, a transmission system will be described. A digital IQ signal of a transmission signal is output from a baseband unit (BB) 1, and the digital IQ signal is converted into an analog signal by a digital / analog conversion unit (DAC) 2. The analog signal is quadrature modulated by a quadrature modulation unit (QMOD) 3 and output as a radio frequency band signal.

  The radio frequency band signal is preamplified by a preamplifier (PreAMP) 4, amplified to a high output signal by a transmission output amplifier (hereinafter referred to as a power amplifier (PA)) 6, and transmitted / received signal combining unit (hereinafter referred to as a circulator). (Referred to as (CIR)). The output signal of the circulator (CIR) 7 is subjected to removal of unnecessary wave components and the like by the front end unit (FE) 8 and output as a transmission wave from the antenna (ANT).

  The output signal of the power amplifier (PA) 6 is coupled, converted to an intermediate frequency band by a feedback converter (FB-CONV) 9, and converted to a digital signal by an analog / digital converter (ADC) 10. The feedback signal converted into the digital signal is returned to the baseband unit (BB) 1 and used as a processing signal of the digital predistorter (DPD) 11 and at the same time used to derive the value of the transmission output level.

  Next, the reception system will be described. The signal input from the antenna (ANT) is subjected to removal of unnecessary wave components outside the band by the front end unit (FE) 8, and then the reception signal is transmitted by the circulator (CIR) 7. And input to the reception switch (RX RFSW) 13. The reception switch (RX RFSW) 13 is a switch provided to prevent an excessive output level of a transmission signal from being circulated and input to a reception input amplifier such as a low noise amplifier (LNA) 14.

  A signal output from the reception switch (RX RFSW) 13 is input to a reception input amplifier such as a low noise amplifier (LNA) 14, amplified by low noise, and then input to a reception converter (RX-CONV) 15. The reception signal is converted into an intermediate frequency band by a reception converter (RX-CONV) 15, converted into a digital signal by an analog / digital conversion unit (ADC) 16, and input to the baseband unit (BB) 1 for demodulation processing. Is done.

  In the conventional TDD transmission / reception apparatus, when an overpower is detected by the alarm determination unit (ALM) 12 in the baseband unit (BB) 1, the reception switch (RX RFSW) 13 is cut off, and a sneak signal of the transmission system is generated. Processing is performed so as not to input to the low noise amplifier (LNA) 14.

  In addition, as a conventional TDD radio transmission / reception device, means for preventing the influence of a reflection signal of an abnormal level of a transmission signal from an antenna or the like on a low noise amplifier, detection of the occurrence of a reflection signal of an abnormal level, and detection of an abnormality A TDD wireless transmission / reception apparatus that includes a means for generating a signal and detects an abnormal transmission / reception state to eliminate useless operation is known, for example, from Patent Document 1 below.

JP 2008-147934 A

  In the conventional TDD transmission / reception apparatus, the output signal of the power amplifier (PA) 6 is extracted by coupling, and the feedback signal is baseband via the feedback converter (FB-CONV) 9 and the analog-digital converter (ADC) 10. Unit (BB) 1 and the baseband unit (BB) 1 derives the value of the transmission output level.

  Then, the value of the transmission output level is determined by the alarm determination unit (ALM) 12, and after it is determined that the output is excessive (abnormally high output), the reception switch (RX RFSW) 13 is shut off. As a result, after an overpower level is output from the power amplifier (PA) 6, it is possible time until it is determined by the alarm determination unit (ALM) 12 and the reception switch (RX RFSW) 13 is cut off. In the meantime, a high-power signal was applied to the receiving input amplifier such as the low noise amplifier (LNA) 14 of the receiving system. For this reason, a receiving input amplifier such as a low noise amplifier (LNA) 14 having high power tolerance must be used.

  However, a device having a sufficiently high power tolerance is not always readily available when adding a frequency to be used or cost reduction, and the high power tolerance of the low noise amplifier (LNA) 14 is not always available. Therefore, the switching to the cutoff of the reception switch (RX RFSW) 13 is not completed within the time period in which the low noise amplifier (LNA) 14 is broken, or the characteristic deterioration may occur.

  In addition, when oscillation occurs at an unexpected frequency due to a failure in a transmission system circuit or the like, the frequency characteristics of the feedback converter (FB-CONV) 9 or out of the frequency range in which the analog-digital converter (ADC) 10 can operate. As a result, the output level of the transmission system is not properly detected. For this reason, even though it is possible to prevent unnecessary radio waves from being transmitted to the outside by the front end unit (FE) 8, there is a risk that the protection of the reception system circuit is insufficient and a failure of the reception system circuit may occur. The present invention provides a TDD transmission / reception apparatus in which protection against wraparound of an excessive output signal of a transmission system to a reception system circuit is more reliably and accurately performed.

TDD scheme transceiver of the present invention, the transmission signal power-amplified by the transmission power amplifier, and transmitted from the antenna via the transmission and reception signal coupling unit, the signal received by the antenna, via the transceiver signal coupling unit a T DD scheme transceiver to be input to the receiver input amplifier, the transmitter output current or output voltage of the preamplifier of the preceding monitors the output amplifier, over the output current output current or output voltage is predefined value or and over power determining means for determining whether or not exceeded over the output voltage value, the transmitting and receiving signal coupling unit provided between the reception input amplifier, the relative said that by the excessive output determining means and said transmission output amplifier the over power determination signal of the preamplifier, and a reception switch for interrupting a signal route for inputting the received signal to the receiving input amplifier.

  In addition, the output current or output voltage of the transmission signal at the front end unit provided between the transmission / reception signal coupling unit and the antenna is monitored, and the output current or output voltage is defined as an over-output current value or over-output that is defined in advance. An overpower determining means for determining that the voltage value has been exceeded, and provided between the transmission / reception signal coupling unit and the reception input amplifier, and when the overoutput of the transmission output amplifier is detected by the overpower determination means And a reception switch that cuts off a signal path for inputting the reception signal to the reception input amplifier.

  In addition, the output current or output voltage of the preamplifier in front of the transmission output amplifier is monitored, and it is determined that the output current or output voltage has exceeded a predetermined overoutput current value or overoutput voltage value. The reception signal is provided by a determination unit, and a signal that is provided between the transmission / reception signal coupling unit and the reception input amplifier, and that is output when an excessive output of the transmission output amplifier is detected by the excessive output determination unit. And a receiving switch for cutting off a signal path input to the low noise amplifier.

  In a TDD transmission / reception apparatus, when a transmission signal with an overpower level is output from the transmission system, the transmission system detects the overpower of the transmission system in a short time, and the reception system circuit with respect to the wraparound of the transmission system overpower signal to the reception system circuit Can be promptly and reliably and accurately performed, and destruction or deterioration of characteristics of the receiving system circuit can be prevented.

It is a figure which shows explanatory drawing of the overoutput protection function of a TDD system transmission / reception apparatus. It is a figure which shows explanatory drawing of the overoutput protection function by monitoring the drain current of FET of a power amplifier. It is a figure which shows the processing flow of the overoutput protection by monitoring the drain current of a power amplifier. It is a figure which shows explanatory drawing of the overoutput protection function by monitoring the output electric power of a power amplifier. It is a figure which shows the processing flow of the overoutput protection function by monitoring the output electric power of a power amplifier. It is a figure which shows the structural example of the overoutput protection function by monitoring the output electric power of a preamplifier. It is a figure which shows the processing flow of the overoutput protection by monitoring the output power of a preamplifier. It is explanatory drawing of the diagnostic function of a low noise amplifier. It is a figure which shows the structural example of the conventional TDD system transmission / reception apparatus.

  FIG. 1 is an explanatory diagram of the over-output protection function of the TDD transmission / reception apparatus. The over-output protection function is a first means (1) as an output current (for example, drain current) of an amplification element (for example, FET: Field Effect Transistor) used in a transmission output amplifier (hereinafter referred to as a power amplifier (PA)) 6. ) Or the output voltage is monitored, and when the output current or output voltage reaches the specified maximum current value or the specified maximum voltage value of the amplifying element, it is determined that the power amplifier (PA) 6 is in an excessive output state, and reception is performed. The switch (RX RFSW) 13 is configured to be cut off. With this configuration, not only the frequency band during normal operation but also the transmission output signal of an unexpected frequency due to oscillation due to a circuit failure, etc., it becomes possible to detect over output, and the accompanying high power signal to the receiving system The wraparound can be suppressed in a short time.

  Moreover, the structure which interrupts | blocks the receiving switch (RX RFSW) 13 by the over output alarm (Over Power Alarm) of the power amplifier (PA) 6 can be provided. With this configuration, even when an abnormality occurs in the signal processing of the baseband unit (BB) 1, it is possible to detect overpower, and to suppress a large power wraparound to the receiving system in a short time.

  Further, as the second means (2), the output power of the preamplifier (PreAMP) 4 is monitored by a detector provided on the output side of the preamplifier (PreAMP) 4, and the output power becomes a specified value or more. When the output is excessive, the transmission switch (TX RFSW) 5 and the reception switch (RX RFSW) 13 provided on the output side of the preamplifier (PreAMP) 4 are cut off.

  With this configuration, it becomes possible to detect overpower when abnormality occurs in the signal processing of the preamplifier (PreAMP) 4 and the baseband unit (BB) 1, and by shutting off the transmission switch (TX RFSW) 5, By preventing an excessive signal from being input to the power amplifier (PA) 6 and cutting off the reception switch (RX RFSW) 13, it is possible to suppress a large amount of power from entering the reception system in a short time.

  As a third means (3), the gate bias voltage of an amplifying element (for example, FET) used in a receiving input amplifier (hereinafter referred to as a low noise amplifier (LNA)) 14 provided in the receiving system is used for transmission and reception. A configuration is provided in which switching is performed in accordance with the switching timing, and a change in output current or output voltage (for example, drain current or voltage) at that time is confirmed. With this configuration, even when a high-power signal wraps around the reception system, the normality of the operation of the low-noise amplifier (LNA) 14 in the reception system can be sequentially confirmed, and malfunctions can be monitored.

  FIG. 2 is an explanatory diagram of an overoutput protection function by monitoring the drain current of the FET of the power amplifier (PA) 6. As a means for monitoring the drain current of the FET of the power amplifier (PA) 6, an overload limit value (Overload Limit) is set in the power supply unit (PS: Power Supply) 20. In the following description, since there is no particular difference between the output current and the output voltage, the output current will be mainly described, but the same applies to the output voltage.

  The overpower limit value is set to, for example, 1.05 times the maximum current (Maximum Current) during normal operation of the drain current of the FET of the power amplifier (PA) 6, and the drain current exceeding the overpower limit value flows. When this happens, an over power alarm is issued and transmission of the transmission signal is stopped.

  The over output protection function of the TDD transmission / reception apparatus defines an over output current value that is assumed to be an over output of the output signal of the FET of the power amplifier (PA) 6 as a value lower than the above-described over output limit value. Then, the reception switch (RX RFSW) 13 is cut off when this over-output current value is reached. As this over-output current value, the drain current of the FET of the power amplifier (PA) 6 can be the maximum current value during normal operation.

  By monitoring the change in the output current of the FET of the power amplifier (PA) 6, even if an excessive signal outside the band is output due to abnormal oscillation of the preamplifier (PreAMP) 4 or the power amplifier (PA) 6, etc. It is detected as a current, and an overpower can be detected immediately.

  FIG. 3 shows a process flow of over output protection by monitoring the drain current of the power amplifier (PA) 6. When the power supply unit (PS) detects that the upper limit set value of the maximum current (Maximum Current) set during the normal operation set as the over-output current value is exceeded (3-1), the reception switch (RX RFSW) 13 is turned off. An (OFF) signal is generated (3-2). The cutoff (OFF) signal is sent to the reception switch (RX RFSW) 13, and the reception switch (RX RFSW) 13 is cut off (OFF) to prevent the over-output signal from entering the reception system (3-3).

  FIG. 4 is an explanatory diagram of an overoutput protection function by monitoring the output power of the power amplifier (PA) 6. In the conventional example, the overpower detection function is mounted on the digital predistorter (DPD) 11 of the baseband unit (BB) 1. However, the overpower detection function is different from that of the baseband unit (BB) 1. For example, a detection unit (DET) 41 and an overpower determination unit 42 are provided on the output side of the front end unit (FE) 8 independent of the baseband unit (BB) 1.

  The excessive output of the transmission signal output from the front end unit (FE) 8 is detected and determined by the detection unit (DET) 41 and the excessive output determination unit 42. Then, a control signal for the reception switch (RX RFSW) 13 is supplied from the overpower determination unit 42, and the reception switch (RX RFSW) 13 is switched to a cut-off state at the time of excessive output. With this configuration, even when the baseband unit (BB) 1 malfunctions, the protection operation for the reception system is reliably performed.

  FIG. 5 shows a processing flow of the over-output protection function by monitoring the output power of the power amplifier (PA) 6. The detection unit (DET) 41 detects the output power of the front end unit (FE) 8 (5-1). Based on the output power detection result of the detection unit (DET) 41, the overoutput determination unit 42 determines overoutput, and generates a cutoff (OFF) signal of the reception switch (RX RFSW) 13 at the time of overoutput (5-2) ). The cut-off (OFF) signal is sent to the reception switch (RX RFSW) 13 to cut off the reception switch (RX RFSW) 13 and prevent the over-output signal from entering the reception system (5-3).

  FIG. 6 shows a configuration example of the over-output protection function by monitoring the output power of the preamplifier (PreAMP) 4. A detector (DET) 61 is provided on the output side of the preamplifier (PreAMP) 4, and the output power of the preamplifier (PreAMP) 4 is monitored by the detector (DET) 61.

  The output power detected by the detection unit (DET) 61 is compared with a predetermined threshold value by an overpower determination unit (COMP) 62, and when the output power exceeds the threshold value and is determined to be an excessive output, a preamplifier A control signal for cutting off the transmission switch (TX RFSW) 5 provided on the output side of the (PreAMP) 4 is transmitted, and transmission of the output signal after the preamplifier (PreAMP) 4 is blocked by the transmission switch (TX RFSW) 5. .

  The embodiment of FIG. 6 is due to an excessive output in the intermediate stage circuit of the transmission system. In order to distinguish it from the output cutoff due to the failure of the power amplifier (PA) 6 in the final stage, the baseband part (BB) 1 is The preamplifier (PreAMP) 4 sends a signal indicating output interruption due to the occurrence of excessive output. Further, this signal can be used as a cutoff signal for shutting off the reception switch (RX RFSW) 13.

  FIG. 7 shows a process flow of over output protection by monitoring the output power of the preamplifier (PreAMP) 4. The detector (DET) 61 detects the output power of the preamplifier (PreAMP) 4 (7-1). The overpower determination unit (COMP) 62 determines overpower based on the output power detection result by the detection unit (DET) 61, and generates a cutoff (OFF) signal of the transmission switch (TX RFSW) 5 at the time of overpowering (7 -2).

  The transmission switch (TX RFSW) 5 is cut off (OFF) by sending a cut off (OFF) signal, and the input signal to the power amplifier (PA) 6 is cut off (7-3). At the same time, the baseband unit (BB) 1 is notified of a signal indicating an overpower at the preamplifier (PreAMP) 4 and the reception switch (RX RFSW) 13 is cut off (OFF) to receive the overpower signal. (7-4).

FIG. 8 is an explanatory diagram of the diagnostic function of the low noise amplifier , and is an explanatory diagram of the monitoring function of the low noise amplifier (LNA) 14. The bias of the gate voltage of the amplifying element of the low noise amplifier (LNA) 14 is expressed by the TDD method. switch Therefore the switching timing of the transmission of the reception, monitoring a change in the drain current and the drain voltage of the amplifying element of the low noise amplifier 14.

  That is, a low-noise amplifier that inputs a switching control signal of a TDD switching control unit (TDDSW CONT) 81 that controls switching between transmission and reception in the TDD system to the analog switch 82 and outputs from the analog switch 82 by the switching control signal The bias of the gate voltage of (LNA) 14 is switched.

  The analog switch 82 includes different gate bias voltages, for example, a gate bias voltage (On bias) 83 during normal operation of the low noise amplifier (LNA) 14 and a gate bias voltage that disables the low noise amplifier (LNA) 14. (Off bias) 84 is input, and the analog switch 82 applies one of the gate bias voltages to the gate of the low noise amplifier (LNA) 14 in accordance with the switching control signal. Then, the drain voltage that is the output voltage of the low noise amplifier (LNA) 14 is monitored by an amplification element output monitoring means using an operational amplifier 85 or the like.

FIGS. 8A and 8B are explanatory diagrams of operations during normal operation and abnormal operation. TDDSW is a switching control signal between TDD transmission and reception, and OPAMP output is a low noise amplifier (LNA) 14. The operational amplifier output for monitoring the output signal is shown. As shown in FIG. 8A, when the drain voltage of the low noise amplifier 14 changes within a predetermined range in synchronization with the switching timing of time division duplex (TDD), it is determined as normal. Further, as shown in FIG. 8B, when the change synchronized with the switching timing of the time division duplex (TDD) does not occur, it is determined that the low noise amplifier (LNA) 14 is malfunctioning. As a result, the occurrence of a failure in the low noise amplifier (LNA) 14 can be detected .

8A and 8B show the output of the operational amplifier (OPAMP) for detecting the output signal output of the low noise amplifier (LNA) 14, and as described above, the transmission / reception switching control is performed. When it is possible to detect a change in a predetermined level synchronized with the signal, it is determined to be normal, and as indicated by the detection of a mismatch between dotted ellipses, if there is no change in the predetermined level, a failure of the low-noise amplifier (LNA) 14 has occurred. judge.

DESCRIPTION OF SYMBOLS 1 Baseband part 2 Digital analog conversion part 3 Quadrature modulation part 4 Preamplifier 5 Transmission switch 6 Transmission output amplifier (power amplifier)
7 Transmission / reception signal coupling part (circulator)
8 Front-end section 9 Feedback converter 10 Analog-digital conversion section 11 Digital predistorter 13 Reception switch 14 Low noise amplifier 15 Reception converter 16 Analog-digital conversion section

Claims (3)

T DD scheme a transmission signal power-amplified by the transmission power amplifier, and transmitted from the antenna via the transmission and reception signal coupling unit, the signal received by the antenna, and inputs the received input amplifier via the transceiver signal coupling unit In the transmitting / receiving device,
An overoutput that monitors the output current or output voltage of the preamplifier in front of the transmission output amplifier and determines whether the output current or output voltage exceeds a predefined overoutput current value or overoutput voltage value A determination means;
Provided between the reception input amplifier and the transmitting and receiving signal coupling unit, wherein the over power determination signal of the preamplifier for by that said transmission output amplifier over-output determining unit, the received signal to the receiving input amplifier TDD scheme reception apparatus characterized by comprising a reception switch for interrupting an input signal route. Provided between the preamplifier and the transmission output amplifier, and the output signal of the preamplifier is input to the transmission output amplifier by the overpower determination means by a determination signal based on the determination of the overoutput of the transmission output amplifier. The TDD transmission / reception apparatus according to claim 1, further comprising: a transmission switch that blocks a signal path to be transmitted. The gate bias voltage of the amplification element of the reception input amplifier is switched to a different voltage according to the switching timing between transmission and reception, the change in the output current or output voltage of the amplification element is monitored, and the switching timing of the gate bias voltage is set. 2. An amplifying element output monitoring means for determining that the amplifying element is abnormal when a change range of an output current or an output voltage of the amplifying element does not exceed a predetermined range in synchronization. the TDD system transceiver.

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