JPH05244034A - Radio transmitter/receiver - Google Patents

Abstract

PURPOSE:To prevent the reception band noise of the duplex type radio transmitter/receiver from increasing and to reduce the size and power consumption of the driver amplifier of a transmission part. CONSTITUTION:The transmission part wherein the signal generated by an oscillator 1 is amplified by a power amplifier 6 after passed through a buffer amplifier 3 and the driver amplifier 5 is provided with trap circuits 2 and 4 which are synchronized with a reception frequency band at least between the oscillator 1 and buffer amplifier 3 or the buffer amplifier 3 and driver amplifier 5. Consequently, the need for a band-pass filter for suppressing the reception band noise is eliminated, the passing loss in the band-pass filter is eliminated, and the driver amplifier is reduced in size and power consumption.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a duplex type radio transmitter / receiver, and more particularly to the structure of a transmitter.

[0002]

2. Description of the Related Art As shown in FIG. 3, a transmitter of a conventional radio transmitter / receiver includes an oscillator 1, a buffer amplifier 3, a driving amplifier 5, a bandpass filter 8, a power amplifier 6, a duplexer 7. The driving amplifier 5 amplifies the transmission signal f _T ′, and the band filter 8 attenuates the reception band noise f _N ′ accompanying the transmission signal. For example,
As shown in the gain state in FIG. 4, the transmission signal generated by the oscillator 1 passes through the buffer amplifier 3, and f _T ′ is +2 dBm,
f _N ′ becomes −96 dBm. Further, the signal passes through the driving amplifier 5, the reception band noise is attenuated by the band filter 8 (for example, the pass loss is 5 dB, the reception band attenuation amount is 30 dB), is input to the power amplifier 6, passes through the duplexer 7, and is output to the output end. Will be issued.

[0003]

In such a conventional structure of the transmitting section, the band-pass filter 8 is provided between the driving amplifier 5 and the power amplifier 6 for the purpose of attenuating noise in the reception frequency band. The band-pass filter 8 also becomes ultra-miniaturized with the miniaturization of the transmission / reception device, and thus the pass loss becomes large (approximately 5 dB with the ultra-miniature SAW filter). Therefore, in order to supply the required input level (normally +7 dBm) to the power amplifier 6, it is necessary to amplify the pass loss of the bandpass filter 8 by the drive amplifier 5, and the transistor used for the drive amplifier 5 is required. Since a high-power device having a large component size is used as the device, miniaturization of the transmitter / receiver is hindered.

By the way, in the example of FIG. 4, the gain of the driving amplifier 5 is required to be 10 dB and the output level is +12 dBm, and it is necessary to use a high output element or to flow a large amount of current consumption. Further, reception band noise f _N ′ input to the power amplifier 6
Is -113 dBm. Even when the high output element is not used, high output (about 1
In order to obtain 20 dBm), the current consumption increases, and there is a problem that the usage time is greatly limited in a device that supplies power by a battery. An object of the present invention is to provide a wireless transmission / reception device capable of preventing an increase in reception band noise, downsizing a driving amplifier, and saving power.

[0005]

The present invention provides a trap circuit tuned to a reception frequency band between at least one of an oscillator and a buffer amplifier or between a buffer amplifier and a driving amplifier. .

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of an embodiment of the present invention, in which 1 is an oscillator, 3 is a buffer amplifier, 5 is a driving amplifier, 6 is a power amplifier, and 7 is a duplexer. is there. Then, trap circuits 2 and 4 tuned to the reception frequency band are inserted between the oscillator 1 and the buffer amplifier 3 and between the buffer amplifier 3 and the driving amplifier 5, respectively.

Looking at the gain in this configuration, as shown in FIG. 2, the transmission signal f _T generated by the oscillator 1 (for example,
C / N = 100 dB output level 0 dBm passes through the trap circuit 2 (for example, passage loss 1 dB, trap 15 dB), f _T is −1 dBm, and reception band noise f _N is −115 dB.
m. Next, the buffer amplifier 3 (for example, gain 2 dB,
NF = 2 dB), f _T is +1 dBm and f _N is −
It becomes 111 dBm, and when passing through the trap circuit 4, f _T
Is 0 dBm and f _N is -126 dBm. Then, it is input to the driving amplifier 5 and amplified to a required level (for example, +7 dBm) of the power amplifier 6. Therefore, the gain of the driving amplifier 5 is +8 dB and the output level is +7 dBm.
Therefore, assuming that NF is 3 dB, f _N becomes −115 dBm at the input of the power amplifier.

Therefore, it is not necessary to use a driving amplifier 5 having a large gain, so that it is possible to prevent the driving amplifier 5 from being increased in size and power consumption and to prevent an increase in reception band noise. . In this example,
Although the trap circuit is inserted between the oscillator 1 and the buffer amplifier 3 and between the buffer amplifier 3 and the driving amplifier 5, the trap circuit may be inserted only between any one of them. , Substantially the same effect can be obtained.

[0009]

As described above, according to the present invention, the trap circuit tuned to the reception frequency band is provided between at least one of the oscillator and the buffer amplifier, or between the buffer amplifier and the driving amplifier. At the input of the power amplifier in the subsequent stage, there is an effect that the drive amplifier can be downsized and the power consumption can be realized while realizing the reception band noise equivalent to that of the conventional transmission unit.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of an embodiment of a wireless transmission / reception device of the present invention.

FIG. 2 is a diagram showing the gain of the device of FIG.

FIG. 3 is a block configuration diagram of an example of a conventional wireless transmission / reception device.

FIG. 4 is a diagram showing the gain of the device of FIG.

[Description of Reference Signs] 1 oscillator 2 trap circuit 3 buffer amplifier 4 trap circuit 5 driving amplifier 6 power amplifier 7 duplexer

Claims (2)

[Claims] 1. A buffer amplifier for buffering a signal generated by an oscillator,
In a wireless transmission / reception device including a transmission unit configured to perform power amplification by a power amplifier and transmit after passing through a driving amplifier, at least between the oscillator and the buffer amplifier, or between the buffer amplifier and the driving amplifier. A wireless transmission / reception device characterized in that a trap circuit tuned to a reception frequency band is provided between the two. 2. The wireless transmission / reception device according to claim 1, wherein the transmission unit is a transmission unit of a duplex transmission / reception device that performs transmission and reception simultaneously.