JPH10327090A - Transmitter-receiver of superheterodyne system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmitter-receiver of a superheterodyne system with a small size and low power consumption by using a frequency divider so as to use an oscillator in common for each section. SOLUTION: A conventional transmitter-receiver is provided with a reference oscillator 40, a 1st phase locked loop PLL circuit 51, a 2nd PLL circuit and a 3rd PLL circuit 53. An output of the reference oscillator 40 is given to the 1st, 2nd and 3rd PLL circuits, an output of the 1st PLL circuit is used for a 1st local oscillating frequency and an output of the 2nd PLL circuit is used for a 2nd local oscillating frequency and an output of the 3rd PLL circuit is fed to a modulator 21 as a transmission modulation frequency. In the transmitter-receiver in this invention, the 2nd PLL circuit is eliminated and a frequency divider 41 having a prescribed frequency division ratio is provided, an output of a reference oscillator 40 is used for a 2nd local oscillating frequency and it is given to a 1st PLL circuit 51 and a 3rd PLL circuit 53 via a frequency divider 41.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a super-heterodyne transceiver used in portable telephones, automobile telephones and the like.

[0002]

2. Description of the Related Art FIG. 4 is a diagram showing an example of the configuration of a conventional super-heterodyne transceiver used in a portable telephone, a car telephone or the like. As shown in the drawing, a conventional super-heterodyne transceiver includes an antenna 1, an antenna duplexer 2, a high-frequency amplifier 3, a band-pass filter 4, a mixer 5, a first intermediate frequency filter 6, and a first intermediate frequency amplifier 7. , Mixer 8, second intermediate frequency filter 9, second intermediate frequency amplifier 10, modulator 21, low-pass filter 22, mixer 23, band-pass filter 24, power amplifier 25, and a first local oscillation circuit to be described later. The configuration includes two local oscillation circuits and an oscillation circuit used for modulating a transmission signal.

The oscillation circuit includes a reference oscillator 30, such as a temperature-compensated crystal oscillator, and a PLL (phase locked loop) circuit 5.
1, a PLL circuit 52 and a PLL circuit 53. The PLL circuit 51 includes a loop circuit including a phase comparator 31, a low-pass filter 32, and a voltage-controlled oscillator 33. The PLL circuit 52 includes a phase comparator 16, a low
It is composed of a pass filter 15 and a voltage controlled oscillator 14,
The PLL circuit 53 includes a phase comparator 13, a low-pass filter 1,
2 and a voltage controlled oscillator 11.

[0004] PLL circuit 51, PLL circuit 52 and PL
The L circuit 53 receives an output frequency of the reference oscillator 30 and outputs a predetermined frequency. The output of the PLL circuit 51 is supplied to the mixer 5 as a first local oscillation frequency, and is also supplied to the mixer 23 to be converted to a transmission frequency. P
The output of the LL circuit 52 is supplied to the mixer 8 and used for the second intermediate frequency conversion. The output of the PLL circuit 53 is the modulator 2
The modulated signal is supplied to 1 and the transmission signal is modulated. The output is supplied to a mixer 23 after unnecessary waves are removed by a low-pass filter 22.

At the time of reception, a received signal received by the antenna 1 is sent to the high-frequency amplifier 3 via the antenna duplexer 2 and amplified. After the unnecessary signal is removed by the band-pass filter 4, the amplified signal is down-converted by the first local oscillation frequency in the mixer 5, the unnecessary signal is removed by the first intermediate frequency filter 6, and the first intermediate frequency The signal is amplified by the first intermediate frequency amplifier 7. Further, the first intermediate frequency signal is down-converted by the mixer 8 at the second local oscillation frequency for reception from the PLL circuit 52, and
Unwanted waves are removed by the intermediate frequency filter 9 to become a second intermediate frequency signal, which is amplified by the second intermediate frequency amplifier 10 and demodulated by a demodulator (not shown).

On the other hand, the output of the base band is modulated by the modulator 21 at the output frequency of the PLL circuit 53, the unnecessary wave is removed by the low-pass filter 22, and mixed with the first local oscillation frequency by the mixer 23. , Bandpass filter 2
After the unnecessary wave is removed in step 4, the signal is amplified to a specified power by the power amplifier 25 and supplied to the antenna 1 via the antenna duplexer 2.

FIG. 5 is a diagram showing a configuration example of a conventional transceiver using a circuit comprising a mixer 34, a band-pass filter 35 and an amplifier 36 instead of the PLL circuit 51 for outputting the first local oscillation frequency. This is an example of a transceiver that employs a modulation type transmission system. The outputs of the PLL circuit 52 and the PLL circuit 53 are mixed by the mixer 34, the output frequency of which is removed by the band-pass filter 35 and amplified by the amplifier 36, and then supplied to the mixer 5 as the first local oscillation frequency. At the same time, it is supplied to the modulator 21.

FIG. 6 shows a conventional circuit in which a changeover switch 43 for switching between two reception frequency bands is provided in a reception circuit, and a PLL circuit 52 for outputting a second local oscillation frequency is provided with means for switching the oscillation frequency corresponding to the frequency band. FIG. 3 is a diagram illustrating a configuration example of a transceiver. This figure is also an example of a transceiver employing a direct modulation type transmission system.

[0009]

However, as described above, the conventional transceiver shown in FIG.
Since the PLL circuit 51 is used as the first local oscillation circuit, the PLL circuit 52 is used as the second local oscillation circuit, and the PLL circuit 53 is used as the oscillation frequency to be supplied to the modulator 21 for transmission, the circuit becomes large-scale. As a result, the power consumption increases, and the area occupied by the oscillator on the substrate increases, making it difficult to reduce the size.

Also, in the example of the direct modulation method shown in FIGS. 5 and 6, the circuits are similarly large because the PLL circuit 52 and the PLL circuit 53 are used, and the power consumption increases due to the driving thereof. However, there has been a problem that the area occupied by the oscillator in the substrate becomes large and it is difficult to reduce the size.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and in order to solve the above problems, a superheterodyne transceiver having a reduced size and reduced power consumption by using a frequency divider and sharing an oscillator. The purpose is to provide.

[0012]

According to a first aspect of the present invention, there is provided a reference oscillator comprising a reference oscillator, a first PLL circuit, a second PLL circuit, and a third PLL circuit. Is supplied to a first PLL circuit, a second PLL circuit, and a third PLL circuit, the output of the first PLL circuit is used as a first local oscillation frequency, and the output of the second PLL circuit is Used as the 2 local oscillation frequency and the third P
In a super-heterodyne transceiver that supplies the output of the LL circuit to the modulator as a transmission modulation frequency, the second
And a frequency divider having a predetermined frequency division ratio is provided, the output of the reference oscillator is used directly as the second local oscillation frequency, and the output of the reference oscillator is supplied to the first oscillator via the frequency divider. And a third PLL circuit.

According to a second aspect of the present invention, there is provided a reference oscillator, a first PLL circuit, a second PLL circuit, and a mixer, and outputs the output of the reference oscillator to the first PLL circuit and the second PLL circuit.
And outputs the output of the second PLL circuit to the second PLL circuit.
A super-heterodyne system which is used as a local oscillation frequency, is mixed with an output of a first PLL circuit by a mixer, and uses the output mixed by the mixer as a first local oscillation frequency and supplies the output as a transmission frequency to a modulator. In the transmitter / receiver, the second PLL circuit is deleted, a frequency divider having a predetermined frequency division ratio is provided, and the output of the reference oscillator is directly used as the second local oscillation frequency and supplied to the mixer and the frequency divider. The output of the frequency divider is input to a first PLL circuit.

According to a third aspect of the present invention, there is provided a reception frequency band switch, a reference oscillator, a first PLL circuit, a second PLL circuit for switching an output frequency according to a frequency band, and a mixer. The output is supplied to a first PLL circuit and a second PLL circuit, and the output of the second PLL circuit is used as a second local oscillation frequency and the first PLL circuit is used.
The output of the circuit is mixed by a mixer, the output mixed by the mixer is used as a first local oscillation frequency, and a super-heterodyne transceiver that supplies a modulator as a transmission frequency is provided with a second PLL circuit. Delete it,
A reference oscillator for switching an output frequency according to a frequency band and a switching divider for switching a dividing ratio, wherein an output of the reference oscillator is used as a second local oscillation frequency and supplied to a mixer and a switching divider; Is input to the first PLL circuit.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a super
It is a figure which shows the example of a structure of the transceiver of a heterodyne system.
In the figure, the parts having the same reference numerals as those in the conventional example have been described in the conventional example, and the description thereof will be omitted. As shown in the figure, the super-heterodyne transceiver of the present invention is provided with a reference oscillator 40 such as a SAW (surface acoustic wave) oscillator and a frequency divider 41 having a predetermined frequency division ratio. Is directly supplied to the mixer 8 as the second local oscillation frequency, and is reduced to a predetermined frequency via the frequency divider 41 and supplied to the PLL circuit 51 and the PLL circuit 53.

The output of the reference oscillator 40 is supplied to the mixer 8 as the second local oscillation frequency for reception, and is also frequency-divided by the frequency divider 41 into N and supplied to the PLL circuits 51 and 53. The output of the PLL circuit 51 is supplied to the mixer 5 as a first local oscillation frequency, and is also supplied to the mixer 23 to be converted to a transmission frequency. The output of the PLL circuit 53 is supplied to the modulator 21 and modulates the transmission signal. The output of the PLL circuit 53 is filtered by the low-pass filter 22 to remove unnecessary waves.
Supplied to

As described above, according to the transceiver having the configuration shown in FIG. 1, the reference oscillator 40 and the frequency divider 41 set to a predetermined frequency division ratio N are provided, and the output of the reference oscillator 40 is directly transmitted to the second local oscillator. The frequency is supplied to the mixer 8 and the frequency divider 41
Is supplied to the PLL circuit 51 and the PLL circuit 53 through the PLL circuit 52 (the voltage controlled oscillator 14, the low-pass filter 15, the phase comparator, etc.) used in the conventional transceiver shown in FIG. 16) can be omitted, and the size and power consumption of the device can be reduced. In addition,
Since the frequency divider 41 can be easily integrated into an IC and can be easily incorporated into another IC component, the size can be reduced. Here, when the frequency division ratio N = 1, the frequency divider 41 becomes unnecessary.

FIG. 2 is a block diagram of the conventional transceiver shown in FIG.
The L circuit 52 is deleted. In this embodiment, the output of the reference oscillator 40 is supplied to the mixer 8 as the second local oscillation frequency, and the frequency divided by N is supplied to the PLL circuit 53 via the frequency divider 41. The output and the mixer 34 are mixed, and the output of the mixer 34 is filtered by a band-pass filter 35 to remove unnecessary waves, amplified by an amplifier 36, supplied to the mixer 5 as a first local oscillation frequency, and supplied to the modulator 21. I do.

As described above, according to the transceiver shown in FIG. 2, the PL used in the conventional transceiver shown in FIG.
L circuit 52 (voltage controlled oscillator 14, low-pass filter 1)
5. Since the phase comparator 16) can be omitted, the size and power consumption of the transceiver can be reduced. Note that the frequency divider 41 can be easily integrated into an IC and can be easily incorporated into other components, so that downsizing and low power consumption can be achieved.

FIG. 3 shows an example in which the present invention is applied to a transmitter / receiver (see FIG. 6) which receives two frequency bands by switching between them.
A reference oscillator 40 for switching an output frequency by a switching signal for switching a frequency band and a switching frequency divider 42 for switching a frequency dividing ratio N are provided, and a second local oscillation frequency and a frequency dividing ratio N corresponding to each frequency band are provided by a switching signal. Set. Other operations have been described with reference to FIG.

As described above, even in the case of the transmitter / receiver of the system for switching the reception frequency band shown in FIG. 3, the output frequency of the reference oscillator 40 and the frequency division ratio N of the switching frequency divider 42 are obtained by the switching signal.
By switching between them, the PLL circuit 52 can be eliminated, so that downsizing of the device and low power consumption can be achieved.

[0022]

As described above, according to the first aspect of the present invention, a frequency divider having a predetermined frequency dividing ratio is provided, the output of the reference oscillator is used as the second local oscillation frequency, and the frequency is divided. Means for inputting to the first PLL circuit and the third PLL circuit via a device are provided, and the second PLL circuit is eliminated, so that the size and power consumption of the device can be reduced.

According to the second aspect of the present invention, a frequency divider having a predetermined frequency dividing ratio is provided, and the output of the reference oscillator is used as the second local oscillation frequency and supplied to the mixer and the frequency divider. A means for inputting the output of the frequency divider to the first PLL circuit is provided, and the second PLL circuit is eliminated. Therefore, even in the case of a transceiver employing a direct modulation type transmission system, downsizing of the device and low power consumption are achieved. Can be achieved.

According to the third aspect of the present invention, a reference oscillator for switching an output frequency according to a reception frequency band and a switching frequency divider for switching a division ratio are provided, and an output of the reference oscillator is used as a second local oscillation frequency. In addition, a means for supplying the switching divider and inputting the output of the switching divider to the first PLL circuit is provided and the second PLL circuit is eliminated. The size and power consumption can be reduced. The frequency divider and the switching frequency divider can be easily integrated into an IC and can be easily incorporated into other parts.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of the configuration of a super-heterodyne transceiver according to the present invention.

FIG. 2 is a diagram showing a configuration example of a super heterodyne type transceiver of the present invention.

FIG. 3 is a diagram illustrating a configuration example of a super-heterodyne transceiver according to the present invention;

FIG. 4 is a diagram illustrating a configuration example of a conventional super heterodyne type transceiver.

FIG. 5 is a diagram illustrating a configuration example of a conventional super-heterodyne transceiver.

FIG. 6 is a diagram illustrating a configuration example of a conventional super heterodyne type transceiver.

[Explanation of symbols]

 Reference Signs List 1 antenna 2 antenna duplexer 3 high-frequency amplifier 4 band-pass filter 5 mixer 6 first intermediate-frequency filter 7 first intermediate-frequency amplifier 8 mixer 9 second intermediate-frequency filter 10 second intermediate-frequency amplifier 11 voltage-controlled oscillator 12 low-pass filter DESCRIPTION OF SYMBOLS 13 Phase comparator 14 Voltage controlled oscillator 15 Low pass filter 16 Phase comparator 21 Modulator 22 Low pass filter 23 Mixer 24 Band pass filter 25 Power amplifier 30 Reference oscillator 31 Phase comparator 32 Low pass filter 33 Voltage controlled oscillator 34 mixer 35 band-pass filter 36 amplifier 40 reference oscillator 41 frequency divider 42 switching frequency divider 43 switching switch 51 PLL circuit 52 PLL circuit 53 PLL circuit

Claims (3)

[Claims] 1. A reference oscillator, a first PLL circuit, a second PLL circuit, and a third PLL circuit, wherein an output of the reference oscillator is output from the first PLL circuit, the second PLL circuit, and a third PLL circuit. , The output of the first PLL circuit is used as a first local oscillation frequency, the output of the second PLL circuit is used as a second local oscillation frequency, and a third PLL circuit is used.
In a super-heterodyne transceiver that supplies an output of an L circuit to a modulator as a transmission modulation frequency, a frequency divider having a predetermined frequency division ratio is provided while removing the second PLL circuit, The output of the reference oscillator is used directly as the second local oscillation frequency, and the output of the reference oscillator is input to the first PLL circuit and the third PLL circuit via the frequency divider. Super-heterodyne transceiver. 2. A reference oscillator, a first PLL circuit, a second PLL circuit, and a mixer, wherein an output of the reference oscillator is supplied to the first PLL circuit and the second PLL circuit. 2 is used as the second local oscillation frequency, and the output of the first PLL circuit is mixed with the mixer. The output mixed by the mixer is used as the first local oscillation frequency and is used as the transmission frequency. In a super-heterodyne transceiver for supplying a modulator, the second PLL circuit is omitted, a frequency divider having a predetermined frequency division ratio is provided, and an output of the reference oscillator is directly transmitted to the second oscillator. A super-heterodyne system, wherein the super-heterodyne system is used as a local oscillation frequency, supplied to the mixer and the frequency divider, and inputs an output of the frequency divider to the first PLL circuit. Transceiver. 3. A receiving frequency band switch, a reference oscillator, a first
A PLL circuit, a second PLL circuit for switching an output frequency according to a frequency band, and a mixer. The output of the reference oscillator is supplied to a first PLL circuit and the second PLL circuit. The output is used as a second local oscillation frequency, mixed with the output of the first PLL circuit by the mixer, and the output mixed by the mixer is used as a first local oscillation frequency and supplied to a modulator as a transmission frequency. In the super-heterodyne transceiver, the second PLL circuit is deleted, and a reference oscillator that switches an output frequency according to a frequency band and a switching divider that switches a dividing ratio are provided. It is used as a second local oscillation frequency and supplied to the mixer and the switching divider, and the output of the switching divider is input to a first PLL circuit. Scan, characterized in that - Pa - transceiver heterodyne system.