JP3437670B2 - transceiver - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio equipment of a time division multiplex system, and more particularly, to an electric power for a timing at which a transmission / reception switching antenna switch is switched from a power amplifier to a reception amplifier. The present invention relates to a radio device improved so as to prevent unstable operation of a power amplifier due to a delay in off operation of the amplifier. 2. Description of the Related Art Generally, a radio equipment of a time division multiplex system is shown in FIG.
It is configured as shown in FIG. In FIG. 3, the radio equipment of the time division multiplex system is roughly divided into a transmission system, a reception system, and a control system, and a battery 40 is a power supply for the radio equipment. Are supplied with power supply voltage Vcc via a power supply line (not shown). The transmission system includes a microphone 101, a speech coder (SPCOD) 12, a channel codec coder (CHCOD) 13, a digital modulator (MOD) 14, an adder 15, and a power amplifier (PA) 1.
6. A transmission / reception switching antenna switch (SW) 17 comprising a high-frequency switch circuit, a bandpass filter 19, and an antenna 18. [0005] Here, the speech encoder 12 is a transmitter 101.
The audio signal output from is encoded. Further, the channel codec encoder 13 performs an encoding process on the digitized code signal output from the voice encoder 12 and the digitized control signal output from the control circuit 31. [0006] The digital modulator 14 generates a modulation signal corresponding to the digitized code signal output from the channel codec encoder 13. An adder 15 adds the carrier signal output from the frequency synthesizer 32 to the modulated signal,
Thus, frequency conversion is performed. The power amplifier 16 is controlled by a transmission control signal TX-Vcc CONT from the control circuit 31, and amplifies the output of the adder 15 to a predetermined transmission power. [0009] The transmission / reception switching antenna switch 17 receives an antenna switching timing signal ANT- from the control circuit 31.
It becomes conductive only during a transmission time slot specified by SW CONT, and supplies a radio transmission signal output from the power amplifier 16 to the antenna 18 during this period, and directs the radio transmission signal from the antenna 18 to a base station (not shown). And send it out. On the other hand, the receiving system includes a receiver (RX) 2
1. Digital demodulator (DEMOD) 22, channel codec decoder (CHDEC) 23, speech decoder (SP
DEC) 24 and a receiver 102 comprising a speaker. The receiver 21 is controlled by a reception control signal RX-Vcc CONT from a control circuit 31 to transmit a radio reception signal received by the antenna 18 in a predetermined time slot to the transmission / reception switching antenna switch 17.
, And performs frequency conversion of the wireless reception signal. The digital demodulator 22 performs bit synchronization and frame synchronization with respect to the received signal output from the receiver 21, and supplies the synchronization signal to the control circuit 31. The channel codec decoder 23 decodes the digital demodulated signal output from the digital demodulator 22. The digitized reception signal obtained by the decoding process of the channel codec decoder 23 is
4 and the digitized control signal is supplied to the control circuit 31.
Supplied to The voice decoder 24 performs a decoding process on the digitized reception signal output from the channel codec decoder 23. The analog reception signal restored by the decoding process of the audio decoder 24 is output from the receiver 102. The control system includes a control circuit (CONT) 3
1, a frequency synthesizer (SYN) 32, a reception electric field strength detection circuit (RSSI) 33, and a reception request switch 34. Here, the control circuit 31 includes, for example, a microcomputer as a main control unit, and performs call control and connection control of a wireless line. The synthesizer 32 includes a control circuit 31
Generates a local oscillation frequency required for wireless communication with a base station (not shown). The reception electric field strength detection circuit 33 detects the reception electric field strength of a radio wave transmitted from a base station (not shown), and supplies a detection signal to the control circuit 31. The reception request switch 34 is operated at the time of a reception request of the radio. The transmission signal output from the power amplifier 16 is composed of a transmission burst having a frame structure as shown in FIG. 4 for both the signal transmitted to the control slot and the signal transmitted to the communication slot. The circuit 31 generates a guard time of the transmission burst, that is, a transmission control signal TX-Vcc CONT and an antenna switching timing signal ANT-SW CONT that fall during a period indicated by G in FIG. 4, and the transmission control signal TX-Vcc Power amplifier 1 at the timing when
6 is turned off, and the transmission / reception switching antenna switch 17 is switched from the power amplifier 16 side to the receiver 21 side. FIG. 5 shows the power supply applied to the power amplifier 16 controlled by the transmission control signal TX-VccCONT, the antenna switching timing signal ANT-SW CONT, and the transmission control signal TX-Vcc CONT in the conventional time division multiplex radio. It shows the switching state of the transmission / reception switching antenna switch 17 controlled by the voltage and the antenna switching timing signal ANT-SW CONT. As is apparent from FIG. 5, the antenna switch 17 for transmission / reception switching receives the antenna switching timing signal A
Switching from the power amplifier 16 side (TX) to the receiver 21 side (RX) with almost no time lag with the NT-SW CONT, the applied power supply voltage (TX-Vcc) of the power amplifier 16
Has a waveform as shown in FIG. 5 due to the time constant of the power amplifier 16. That is, since a current of several hundred mA actually flows through the power supply of the power amplifier 16, the transmission control signal TX-V
cc CONT suddenly rises and falls in exactly the same square wave shape as CONT, and does not fall.
As shown in c, it rises and falls with a certain time constant. FIG. 6 shows the power supply voltage (TX-Vcc) applied to the power amplifier 16 when the transmission / reception switching antenna switch 17 shown in FIG. 5 switches from the power amplifier 16 (TX) to the receiver 21 (RX). 3) is an enlarged view of the waveform of FIG. As shown in FIG. 6, the power supply voltage (TX-Vcc) applied to the power amplifier 16 is changed by the transmission / reception switching antenna switch 17 from the power amplifier 16 side (TX) to the receiver 21.
Immediately at the timing of switching to the side (RX).
It does not become V but decreases to 0 V with a constant time constant. In this case, even if the applied power supply voltage (TX-Vcc) starts to decrease from the voltage Vcc indicated by A, the power amplifier 16 does not turn off immediately, but decreases to the voltage indicated by B. It turns off only after a lapse of time. Therefore, there is a moment when the transmission / reception switching antenna switch 17 is turned off while the power amplifier 16 is on, that is, when the antenna switch 17 is switched to the receiver 21 side. Incidentally, the impedance of the transmission / reception switching antenna switch 17 is such that when the transmission is on, the power amplifier 1
6, it becomes approximately 50Ω, but when transmission is turned off, it becomes open. That is, when the transmission / reception switching antenna switch 17 is viewed as the load of the power amplifier 16, the load of the power amplifier 16 is momentarily close to open at the timing shown in FIG. Normally, since the power amplifier 16 is trying to obtain high output with high efficiency, the stable operation region is narrowed. Therefore, when the load of the power amplifier 16 is momentarily close to open, the stable operation is not performed. When performing a burst-like operation, which is a feature of the time-division multiplexing method, there is a problem that oscillation occurs instantaneously in a transient portion such as a rising edge or a falling edge of a transmission burst. As described above, in the conventional time-division multiplex radio, the switching timing of the power supply of the power amplifier is later than the transmission / reception switching timing of the transmission / reception switching antenna switch. In addition, there is a problem that the power amplifier oscillates instantaneously in a transitional portion such as the rising and falling of the transmission burst. SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a time-division multiplex radio which always enables a stable operation at a transmission / reception switching timing of a transmission / reception switching antenna switch. To achieve the above object, the present invention provides a first amplifier for amplifying a transmission burst signal, a second amplifier for amplifying a reception burst signal,
An antenna, connected to the first amplifier, the second amplifier, and the antenna; a transmission burst signal amplified by the first amplifier and output to the antenna; and a transmission burst signal received by the antenna and received by the antenna. A switch for switching between the output burst signal and the transmit burst signal to the receive burst signal at a guard time of the transmit burst signal. At the time of switching, a control signal for turning off the power supplied to the first amplifier is applied to the first amplifier in the guard time, and the power supply voltage applied to the first amplifier is reduced to a predetermined level. At the time when the voltage drops, the switch is moved from the first amplifier to the second amplifier after the control signal. An antenna switching signal for switching to the vessel, characterized by comprising a control means for applying to said switch. According to the present invention, when the control means switches the transmission burst signal to the reception burst signal, the control signal for controlling the power supplied to the first amplifier to be turned off is supplied to the first amplifier during the guard time. When the power supply voltage applied to the first amplifier is reduced to a predetermined level by the control signal, an antenna switching signal for switching the switch from the first amplifier side to the second amplifier is delayed to the control signal when the power supply voltage is applied to the switch. Add. Thus, when the power supply voltage applied to the first amplifier drops to a predetermined level, the switch is switched from the first amplifier to the second amplifier.
The first amplifier can operate stably without oscillation,
Further, since the switch is switched from the first amplifier side to the second amplifier before the power supply voltage applied to the first amplifier becomes completely zero, the switch from the first amplifier side to the second amplifier during the guard time. The switching can be completed. Embodiments of a radio device according to the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a main part of a radio apparatus according to the present invention, and corresponds to the configuration around the transmission / reception switching antenna switch 17 shown in FIG. FIG.
In FIG. 6, portions having the same functions as those shown in FIG. 3 are denoted by the same reference numerals as those used in FIG. 3 for convenience of explanation. In FIG. 1, a radio transmission signal (transmission burst signal) output from a power amplifier 16 is transmitted from an antenna 18 via a transmission / reception switching antenna switch 17 and a band-pass filter 19. The radio transmission signal (reception burst signal) received by the antenna 18 is
The transmission / reception switching antenna switch 17 is applied to a receiver 21 which is a reception low-noise amplifier. Here, the power amplifier 16 includes a control circuit (C
ONT) 31 from the transmission control signal TX-Vcc CON
The driving of the receiver 21 is controlled by the reception control signal RX-Vcc CONT from the control circuit 31 and the transmission / reception switching antenna switch 1 is controlled.
7, the switching timing is controlled by the antenna switching timing signal ANT-SW CONT from the control circuit 31. In this embodiment, the transmission control signal TX-Vcc CONT is set so that the fall timing of the antenna switching timing signal ANT-SWCONT is delayed by Δt from the fall timing of the transmission control signal TX-Vcc CONT. And the antenna switching timing signal ANT-SW CONT is formed by the control circuit 31 and applied to the power amplifier 16 and the transmission / reception switching antenna switch 17, respectively. Here, Δt is the time T, described in FIG.
That is, the time T is set equal to or slightly longer than the time T from when the transmission control signal TX-Vcc CONT falls to when the power amplifier 16 is actually turned off. FIG. 2 shows the power supply voltage applied to power amplifier 16 controlled by transmission control signal TX-Vcc CONT, antenna switching timing signal ANT-SW CONT, and transmission control signal TX-Vcc CONT generated from control circuit 31. , Antenna switching timing signal AN
This figure shows the switching state of the transmission / reception switching antenna switch 17 controlled by the T-SW CONT. As shown in FIG. 2, the fall timing of the antenna switching timing signal ANT-SW CONT is delayed by Δt from the fall timing of the transmission control signal TX-Vcc CONT. In this case, the power amplifier 16 is turned off later than the fall timing of the transmission control signal TX-Vcc CONT, but the fall timing of the antenna switching timing signal ANT-SW CONT applied from the control circuit 31 is controlled by the transmission control signal TX-Vcc CONT. Signal TX-Vcc CONT
Is delayed from the falling timing by Δt, and this Δt is the time T described with reference to FIG. 6, that is, the time T from when the transmission control signal TX-Vcc CONT falls to when the power amplifier 16 is actually turned off. Or slightly longer than the time T, so that the transmission / reception switching antenna switch 17 does not transmit while the power amplifier 16 is on, that is, the state in which the antenna switch 17 is switched to the receiver 21 side does not occur. Thus, it is possible to reliably prevent the power amplifier 16 from oscillating unnecessarily. The transmission / reception switching antenna switch 17
From the power amplifier 16 side (TX) to the receiver 21 side (RX)
As described above, the switching timing is performed in a non-signal time portion called a guard time (portion G) shown in FIG. 4, but since this guard time is about 40 μsec, the transmission control signal TX-Vcc CONT is used. Another inconvenience does not occur due to the above adjustment of the antenna switching timing signal ANT-SW CONT. As described above, according to the present invention,
Since the switch is switched from the first amplifier to the second amplifier when the power supply voltage applied to the first amplifier drops to a predetermined level, the switch is switched from the first amplifier to the second amplifier. When the first amplifier is switched, the first amplifier does not oscillate and can operate stably.
Since the switch is switched from the first amplifier to the second amplifier before the power supply voltage applied to the other amplifier becomes completely zero, the switching from the first amplifier to the second amplifier is completed in the guard time. It has the effect that it can be done.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a main part of a wireless device according to the present invention. 2 shows a transmission control signal TX-Vcc CONT, an antenna switching timing signal ANT-SW CONT and a transmission control signal TX- generated from the control circuit shown in FIG.
Power supply voltage applied to the power amplifier controlled by Vcc CONT, antenna switching timing signal ANT-SW C
The figure which showed the switching state of the antenna switch for transmission / reception switching controlled by ONT. FIG. 3 is a block diagram showing a general configuration of a time-division multiplex wireless device. FIG. 4 is a diagram showing a frame configuration of a signal transmitted to a control slot and a frame transmitted to a communication slot in the configuration shown in FIG. 3; FIG. 5 shows a transmission control signal TX-Vcc CONT, an antenna switching timing signal ANT-SW CONT, and a transmission control signal TX in a conventional time-division multiplex radio apparatus.
-Vcc CONT controlled power supply voltage applied to power amplifier, antenna switching timing signal ANT-SW
The figure which showed the switching state of the antenna switch for transmission / reception switching controlled by CONT. FIG. 6 is a diagram showing the applied power supply voltage (TX−) of the power amplifier at the timing when the transmission / reception switching antenna switch shown in FIG. 5 switches from the power amplifier side (TX) to the receiver side (RX)
The figure which expanded and showed the waveform of (Vcc). [Explanation of Code] 12 Speech encoder (SPCOD) 13 Channel codec encoder (CHCOD) 14 Digital modulator (MOD) 15 Adder 16 Power amplifier (PA) 17 Transmission / reception switching antenna switch (SW) 18 Antenna 19 Band pass Filter 21 Receiver (RX) 22 Digital demodulator (DEMOD) 23 Channel codec decoder (CHDEC) 24 Voice decoder (SPDEC) 31 Control circuit (CONT) 32 Synthesizer (SYN) 33 Received electric field strength detection circuit (RSSI) 34 Receive request switch 40 Battery 101 Transmitter 102 Receiver

Claims (1)

(57) Claims: A first amplifier for amplifying a transmission burst signal, a second amplifier for amplifying a reception burst signal, an antenna, the first amplifier and the second amplifier Switching between a transmission burst signal amplified by the first amplifier and output to the antenna and a reception burst signal received by the antenna and output to the second amplifier. A switch for performing switching from a burst signal to the reception burst signal at a guard time of the transmission burst signal, wherein power is supplied to the first amplifier when switching from the transmission burst signal to the reception burst signal. A control signal for turning off the power supply to the first amplifier during the guard time; Control means for applying, to the switch, an antenna switching signal for switching the switch from the first amplifier to the second amplifier after the control signal when the power supply voltage applied to the switch drops to a predetermined level. A wireless device characterized in that: