JPH05259934A - Transmitting/receiving device - Google Patents

Abstract

PURPOSE:To receive the different frequency bands by using one local oscillation circuit in common by generating a 1st local oscillation signal with the selective use of a reference signal and a dividing signal. CONSTITUTION:An oscillation circuit 44 generates a reference signal S21 and outputs this to a selection circuit 46 and a 1/2-dividing circuit 50. The circuit 46 decides to output the signal S21 to a multiplication circuit 48 directly or via the circuit 50 based on the receiving frequency band. The circuit 48 multiplies the output signal of the circuit 46 by the output signal of an oscillation circuit 52 to generate a 1st local oscillation signal S11. The circuit 52 changes the driving ratio based on the receiving frequency band and outputs an oscillation signal S13 to the circuit 48. Thus it is possible to deal with two receiving frequency bands just with addition of both circuits 50 and 46 by switching the input and output signals of the circuit 50 and then switching the frequency of the signal S21 used for generation of the signal S11.

Description

Detailed Description of the Invention

[0001]

[Table of Contents] The present invention will be described in the following order. Field of Industrial Application Conventional Technology (FIG. 3) Problem to be Solved by the Invention (FIG. 3) Means for Solving the Problem (FIG. 1) Action (FIG. 1) Example (1) Configuration of Example (FIG. 1 and FIG. 2) (2) Effect of the embodiment (3) Other embodiment Effect of the invention

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission / reception device, and can be applied to, for example, digital cellular.

[0003]

2. Description of the Related Art Conventionally, in this type of digital cellular, a desired channel can be received by a double superheterodyne system.

That is, as shown in FIG. 3, in the digital cellular 1, the output signal S1 of the antenna 2 is guided to the mixer 6 through the selection circuit 4, where the local oscillation circuit 10 is connected.
Of the local oscillation signal S2. As a result, the digital cellular 1 switches the frequency of the local oscillation signal S2, selects a desired channel from the received signal S1 having a frequency of 810 to 826 [MHz], and outputs the selected signal as the first intermediate frequency signal S3. Output to the frequency amplifier circuit 12.

The following mixer 14 is provided with a second local oscillation circuit 16
Of the local oscillation signal S4 and the first intermediate frequency signal S3 are multiplied to generate a second intermediate frequency signal S5 having a frequency of 450 [kHz]. As a result, the digital cellular 1 demodulates the second intermediate frequency signal S5 and responds to the calling signal, and at the same time, can receive the voice signal of the call target as necessary.

On the other hand, in the transmission system, the I / Q baseband signal S6 is generated and given to the modulation circuit 18, where the local oscillation signal S7 of the oscillation circuit 20 is used to generate the I / Q baseband signal S6. Quadrature modulation. The amplifier circuit 22 is
The output signal S8 of the modulation circuit 18 is amplified and output to the mixer 24.

The mixer 24 multiplies the output signal S9 of the local oscillation circuit 26 by the output signal S8 and outputs the multiplication signal S10 to the antenna 2 via the selection circuit 4. As a result, in the digital cellular 1, the oscillation frequency of the local oscillation circuit 26 can be switched so that a voice signal or the like can be sent to the call target on the target channel in the frequency band 940 to 956 [MHz].

[0008]

By the way, in this type of digital cellular, the receiving frequency currently in use is 810.
~ 826 [MHz] band (hereinafter referred to as 800 [MHz] band)
In addition to the reception frequencies 1477 to 15 in anticipation of future demand increase
A 13 [MHz] band (hereinafter referred to as 1.5 [GHz] band) is assigned. Therefore, if the number of stations increases in the future,
It is expected that the 1.5 [GHz] band will be used together.

At this time, 800 [MHz] band and 1.5 [GHz]
It would be convenient if the bandwidth and bandwidth could be used by a single device. In this case, the local oscillator circuits 10 and 26
By preparing two systems for each frequency band, it is possible to share the digital cellular in the two bands.
In this case, there is a problem that the entire structure becomes complicated, the shape becomes large correspondingly, and the weight also increases.

The present invention has been made in consideration of the above points, and it is an object of the present invention to propose a transmitting / receiving apparatus which can be used in two frequency bands with a simple structure.

[0011]

In order to solve such a problem, in the first invention, first local oscillation circuits 42, 44, 46, 48, 5 for generating a first local oscillation signal S11 are provided.
0, 52, 54, 56, 58 and the first local oscillation signal S1
1 and the received signal S1 to multiply the first intermediate frequency signal S12
And a second local oscillator circuit 44, 50, 66, 68, 64 for generating a second local oscillation signal.
And the second mixer 1 for generating the second intermediate frequency signal S5 by multiplying the first intermediate frequency signal S12 and the second local oscillation signal.
4 and a demodulation circuit for demodulating the second intermediate frequency signal S5, and the first local oscillation circuits 42, 44, 46, 48, 50,
Reference numerals 52, 54, 56 and 58 denote a reference signal generation circuit 44 that generates a reference signal S21, a frequency dividing circuit 50 that frequency-divides the reference signal S21 to generate a frequency-divided signal, and a reference signal S21 and a frequency-divided signal. A selection circuit 46 that outputs a selection signal and oscillation circuits 48, 52, 54, 56, and 58 that output the first local oscillation signal S11 based on the selection signal are provided, and the selection circuit 54 uses the reference signal S21 and frequency division. The frequency band of the reception signal S1 is switched by switching the signal and switching the frequency of the selection signal.

Further, in the second invention, a modulation circuit 72 for modulating the transmission signal S6 by using a predetermined carrier signal.
A local oscillation circuit 79 that generates a local oscillation signal S22 having a predetermined frequency; a mixer 24 that multiplies the output signal of the modulation circuit 72 and the local oscillation signal S22 and outputs a multiplication signal;
Frequency selection circuits 82, 84, 86, 88 for selectively outputting the signal components of the upper side band and the lower side band of the multiplication signal according to the frequency band of the received signal S1, and the frequency selection circuit 8
The transmission circuits 4, 32, 90 for transmitting the output signals of 2, 84, 86, 88 are provided.

[0013]

The reference signal S21 is divided to generate a divided signal,
If the frequency band of the reception signal S1 is switched by switching the frequency of the selection signal by switching the reference signal S21 and the divided signal by the selection circuit 54, one first local oscillation circuit 42, 44, 46, 48. , 50, 52,
54, 56, and 58 can be used in two frequency bands to receive the reception signal S1, and the entire configuration can be simplified accordingly.

Further, at this time, the output signal of the modulation circuit 72 and the local oscillation signal S22 are multiplied to generate a multiplication signal,
If the signal components of the upper sideband and the lower sideband of this multiplication signal are selectively output according to the frequency band of the received signal S1,
One local oscillation circuit 79 can be used in two frequency bands to output a transmission signal, and the entire configuration can be simplified accordingly.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to the drawings.

(1) Configuration of the Embodiment In FIG. 1, reference numeral 30 denotes a digital cellular phone as a whole, which is capable of transmitting and receiving in the 800 [MHz] band and the 1.5 [GHz] band. Ie Digital Cellular 3
0 applies the reception signal S1 received by the antenna 2 to the selection circuit 4 via the low-pass filter circuit (LPF) 32, and outputs the output signal of the selection circuit 4 to the selection circuit 34.

Here, the selection circuit 34, when receiving the 800 [MHz] band, receives the band pass filter circuit (BPF) 3
While 6 is selected and the output signal is sent, 1.5 [GH
z] band is received, the band pass filter circuit (B
PF) 38 is selected to output the output signal. Corresponding to this, the band pass filter circuits 36 and 38 have pass bands of frequencies 810 to 826 [MHz] and frequencies 1477 to 38, respectively.
It is selected to be 1513 [MHz], so that the signals of the respective frequency bands are extracted from the received signal S1.

The selection circuit 40 selectively outputs the output signals of the bandpass filter circuits 36 and 38 according to the reception band.

The mixer 6 is a bandpass filter circuit 42.
Local oscillation signal S11 input via
Of the first intermediate frequency signal S by multiplying the output signal of
12 is generated and output. Here, the first local oscillation signal S1
1 is 1/2 the reference signal S21 generated by the oscillation circuit 44.
The frequency band can be switched by dividing the frequency by the frequency dividing circuit (1/2) 50 and selecting the input / output signal of the 1/2 frequency dividing circuit (1/2) 50.

That is, the oscillation circuit 44 has a frequency of 1036.4
A reference signal S21 of [MHz] is generated and output to the selection circuit 46 and the 1/2 frequency dividing circuit 50. The selection circuit 46 is 1.5
When the [GHz] band is received, the reference signal S21 is output to the multiplication circuit 48, whereas when the 800 [MHz] band is received, the output signal of the 1/2 divider circuit 50 (that is, the frequency 518.2 [MHz]) is received. Selected) and output to the multiplication circuit 48.

The multiplication circuit 48 multiplies the output signal of the selection circuit 48 and the output signal of the oscillation circuit 52 to generate the first local oscillation signal S11. At this time, the oscillation circuit 52 divides the first local oscillation signal S11 to obtain a comparison result with a predetermined reference signal, and drives the voltage control type oscillation circuit based on the comparison result.

As a result, the oscillator circuit 52 switches the frequency division ratio, and when receiving the 800 [MHz] band, the frequency is changed.
Multiply circuit 4 uses the oscillation signal S13 of 161.8 to 181.8 [MHz]
On the other hand, in the case of receiving the band of 1.5 [GHz], the oscillation signal S13 having a frequency of 310.6 to 346.6 [MHz] is output to the multiplication circuit 48. As a result, in the digital cellular 30, 800 [MHz] is passed through the multiplication circuit 48.
When receiving the band, the local oscillation signal S11 having a frequency of 680 to 700 [MHz] is output, whereas when receiving the band of 1.5 [GHz], the local oscillation signal S11 having a frequency of 1347 to 1383 [MHz] is output. .. This makes Digital Cellular 3
0 is adapted to generate a first intermediate frequency signal S12 having a frequency of 130 [MHz], and the frequency division ratio of the oscillation circuit 52 can be switched to select a desired channel.

In this embodiment, the oscillator circuit 52
In the above, by switching the inductances 56 and 58 connected to the voltage control type oscillation circuit through the selection circuit 54, the oscillation signal S13 can be stably output even when the frequency band is switched.

Thus, by switching the input / output signal of the 1/2 frequency dividing circuit 50 to switch the frequency of the reference signal for generating the local oscillation signal S11, the 1/2 frequency dividing circuit 50 and the conventional local oscillation circuit can be used. It is possible to obtain the digital cellular 30 that can receive two frequency bands with a simple configuration in which only the selection circuit 46 is added and that can receive the two frequency bands with a simple configuration. The bandpass filter circuit 60 and the amplifier circuit 62 form a first intermediate frequency amplifier circuit, which amplifies and outputs the first intermediate frequency signal S12.

The mixer 14 multiplies the output signal of the amplifier circuit 62 and the second local oscillation signal obtained through the low-pass filter circuit 64, thereby generating a second intermediate frequency signal S5 of frequency 450 [kHz]. .. At this time, the digital cellular 30 divides the output signal of the 1/2 frequency dividing circuit 50 by the 1/2 frequency dividing circuits 66 and 68, whereby the frequency 129.55 is obtained.
A second local oscillation signal of [MHz] is generated.

As a result, in the digital cellular 30, the oscillation circuit 44 used to generate the first local oscillation signal S11 is commonly used to generate the second local oscillation signal, which simplifies the overall structure. It is designed to get you. Thus, in the digital cellular 30, the calling signal and the like can be received by amplifying the second intermediate frequency signal S5 by the amplifying circuit 70 and then demodulating it by a predetermined demodulating circuit.

On the other hand, in the transmission system, a carrier signal having a frequency of 259.1 [MHz] output from the 1/2 frequency dividing circuit 66 is given to the quadrature modulation circuit (BM) 72 via the low pass filter circuit 74, Here, the IQ baseband signal S6 is orthogonally modulated. Here, as shown in FIG. 2, the quadrature modulation circuit 72 supplies the I signal SI to the multiplication circuit 74, respectively, and performs balanced modulation using a carrier signal having a frequency of 259.1 [MHz].

Further, the quadrature modulation circuit 72 is a phase circuit (π
/ 2) After delaying the phase of the carrier wave signal by 90 degrees at 75, the output signal of the phase circuit 75 is used as the carrier wave signal to balance-modulate the Q signal SQ at the multiplication circuit 76. Further, the quadrature modulation circuit 72 adds the output signals of the multiplication circuits 74 and 76 by the addition circuit 77, thereby generating and outputting a quadrature modulation signal.

The oscillating circuit 79 is an oscillating circuit having a PLL circuit configuration, and generates a local oscillating signal S22 having a frequency of 1169.9 to 1205.9 [MHz] by switching the frequency division ratio by the system controller 80. The multiplication circuit 24 multiplies the local oscillation signal S22 by the quadrature modulation signal, and thereby subtracts the frequency of the quadrature modulation signal from the frequency of the local oscillation signal S22 (that is, the signal component of the lower sideband). And the frequency of the local oscillation signal S22 and the frequency of the quadrature modulated signal are added (ie, the signal component of the upper sideband).

When the selecting circuit 82 receives the 1.5 [GHz] band, it outputs the output signal of the multiplying circuit 24 to the bandpass filter circuit 84, whereas when it receives the 800 [MHz] band, the multiplying circuit 24 To the bandpass filter circuit 86. Corresponding to this, the band pass filter circuits 84 and 86 respectively have a pass band of frequency.
1429 to 1465 [MHz] and frequencies 940 to 960 [MHz], whereby the upper sideband and lower sideband signal components output from the multiplication circuit 24 are extracted and output. ..

The selection circuit 88 selects the output signal of the bandpass filter circuit 84 when receiving the 1.5 [GHz] band, whereas it selects the output signal of the bandpass filter circuit 86 when receiving the 800 [MHz] band. A signal is selected and the selection signal is output via the amplifier circuit 90. As a result, in the digital cellular 30, the IQ baseband signal is transmitted at frequencies 1429 to 1465 [MHz] when the 1.5 [GHz] band is received, whereas the frequency is 940 to when the 800 [MHz] band is received. The IQ baseband signal is transmitted at 960 [MHz], and the transmission frequency band is switched according to the reception frequency band.

Thus, by selecting the frequency of the carrier signal to a predetermined frequency and selectively outputting the signal components of the upper sideband and the lower sideband obtained through the multiplication circuit 24,
IQ in two frequency bands using one oscillation circuit 79
A baseband signal can be transmitted, and as a result, it is possible to obtain a digital cellular phone having a simple structure as a whole. In the digital cellular 30, the system controller 80 switches and controls the selection circuit 34 and the like to switch the band of the transmission / reception frequency.

(2) Operation of the Embodiment According to the above configuration, when the local oscillation signal is generated based on the reference signal in the receiving system, the output signal of the oscillation circuit and 1/2 division of this output signal. By selectively using the signal and the local oscillation signal to generate a local oscillation signal, one local oscillation circuit can be commonly used in two frequency bands to receive a reception signal, and the digital signal having a simple configuration as a whole can be received. Cellular can be obtained. Further, in the transmission system, the local oscillation signal and the output signal of the modulation circuit are multiplied to generate a multiplication signal, and the signal of the upper sideband or the lower sideband is selectively output from this multiplication signal, thereby generating two signals. The IQ baseband signal can be transmitted by commonly using the local oscillation circuit in the frequency band.

(3) Other Embodiments In the above embodiments, the case where the second local oscillation signal is generated from the output signal of the oscillation circuit 44 in the receiving system has been described, but the present invention is not limited to this. Alternatively, an oscillation circuit may be separately provided depending on the frequency of the second intermediate frequency signal.

Furthermore, in the above-mentioned embodiments, the case where the present invention is applied to digital cellular has been described, but the present invention is not limited to this, and transmitting and receiving for transmitting and receiving a desired signal using two or more different frequency bands. It can be widely applied to devices.

[0036]

As described above, according to the present invention, one local oscillation circuit is commonly used by selectively using the reference signal and its frequency-divided signal to generate the first local oscillation signal. Then, different frequency bands can be received, and a transmitter / receiver having a simple structure can be obtained. In addition to this, one local oscillation circuit is used by multiplying the local oscillation signal by the output signal of the modulation circuit and selectively transmitting the resulting signal components of the upper sideband and the lower sideband. As a result, it is possible to send out transmission signals having different frequency bands, and it is possible to obtain a transmitter / receiver having a simple structure.

[Brief description of drawings]

FIG. 1 is a block diagram showing a digital cellular according to an embodiment of the present invention.

FIG. 2 is a block diagram showing the quadrature modulation circuit.

FIG. 3 is a block diagram showing a conventional digital cellular.

[Explanation of symbols]

1, 30 ... Digital cellular, 2 ... Antenna, 4,
34, 40, 46, 54, 82, 88 ... Selection circuit,
6, 14, 24 ... Mixers 10, 16, 20, 26,
44, 52, 79 ... Oscillation circuit, 36, 38, 42, 6
0, 84, 86 ... Bandpass filter circuit, 48 ...
Multiplier circuit, 50, 66, 68 ... 1/2 frequency divider circuit.

Claims (2)

[Claims] 1. A first local oscillator circuit for generating a first local oscillation signal; a first mixer for multiplying the first local oscillation signal by a received signal to generate a first intermediate frequency signal; and a second mixer. A second local oscillator circuit for generating a local oscillation signal; a second mixer for multiplying the first intermediate frequency signal by the second local oscillation signal to generate a second intermediate frequency signal; and the second intermediate frequency A demodulation circuit for demodulating a signal, wherein the first local oscillation circuit includes: a reference signal generation circuit that generates a reference signal; a frequency dividing circuit that frequency-divides the reference signal to generate a frequency-divided signal; A selection circuit for outputting a reference signal and a selection signal for the frequency division signal; and an oscillation circuit for outputting the first local oscillation signal based on the selection signal, wherein the selection circuit includes the reference signal and the frequency division signal. Switching the signal to switch the frequency of the above selection signal The Rukoto, transmitting and receiving apparatus is characterized in that so as to switch the frequency band of the received signal. 2. A modulation circuit for modulating a transmission signal using a predetermined carrier signal, a local oscillation circuit for generating a local oscillation signal of a predetermined frequency, and an output signal of the modulation circuit multiplied by the local oscillation signal. A mixer for outputting a multiplied signal, a frequency selection circuit for selectively outputting the signal components of the upper sideband and the lower sideband of the multiplied signal according to the frequency band of the received signal, and the frequency selection circuit The transmitter / receiver according to claim 1, further comprising a transmitter circuit for transmitting an output signal.