JP2004228823A - Pll frequency synthesizer module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a PLL frequency synthesizer module which supports a concept for downsizing. <P>SOLUTION: A voltage-controlled oscillator and a power splitter PLL-IC included in a PLL circuit are arranged approximately linearly along a first arrangement line L1, and an amplifier, an attenuator, a first low pass filter, a switch and an external output terminal are arranged approximately linearly along a second arrangement line L2, while the first and second arrangement lines L1 and L2 are parallel to each other. In addition, the directions of signals on the first line L1 and the second line L2 are made reverse to each other, whereby the switch and the VCO output are mounted on a printed wiring board so that they are kept away from each other. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
[0001] 1. Field of the Invention [0002] The present invention relates to a downsized PLL frequency synthesizer module.
[0002]
2. Description of the Related Art In recent years, with the rapid progress of miniaturization accompanying the spread of mobile communication devices such as portable telephones and wireless communication devices such as wireless LANs, PLL frequency synthesizer modules used in these wireless communication devices have been developed. Therefore, higher density mounting is required.
[0003]
As a conventional PLL frequency synthesizer module, for example, there is a module proposed in Japanese Patent Laid-Open No. Hei 10-200405. FIG. 3 (a) shows a block diagram thereof.
A PLL synthesizer 21, an attenuator 22, a buffer amplifier 23, a phase shifter 24, a switch 25, and an output terminal 26 are provided. The output side of the PLL synthesizer 21 is connected to the input side of the attenuator 22, and the output side of the attenuator 22 is connected to the output side. The input side of the buffer amplifier 23 is connected, the output side of the buffer amplifier 23 is connected to the input side of the phase shifter 24, the output side of the phase shifter 24 is connected to the input side of the switch 25, and the switch is connected. 25 and the output terminal 26 are connected.
[0004]
In the GHz band used in the wireless communication system, power is radiated as electromagnetic waves into the air, so EMI countermeasures are indispensable. In a PLL frequency synthesizer module including a switch, switching noise is reduced due to high-density mounting of the PLL circuit. Consideration of the arrangement of the switches so as not to be superimposed on the loop through which the high-frequency current flows and the shield structure are important design factors.
FIG. 3B is a schematic view showing the arrangement of electronic components constituting a conventional PLL frequency synthesizer module.
A substantially rectangular metal frame 31 having shield walls 31a and 31b alternately protruding from a pair of opposed inner surfaces on the upper surface of the printed wiring board 30 is disposed,
This is grounded to form three shield spaces.
First, while disposing the PLL synthesizer 21 in the shield space on the left side in the figure,
The attenuator 22 and the buffer amplifier 23 are disposed in a central shield space in the figure between the shield walls 31a and 31b,
The phase shifter 24 and the switch 25 are arranged in a shield space on the right side in the figure to constitute a PLL frequency synthesizer module.
[0006]
[Patent Document 1] JP-A-10-200405.
[0007]
[Problems to be solved by the invention]
In general, a phase shifter does not lock at higher harmonics, so a PLL circuit with a wide lock range can be realized.
Since the edge operation is used, the output side has a drawback that it is sensitive to input noise and a long time is required to create a high impedance state at the output, so that the output side has a drawback that noise is easily picked up. Therefore, a strict shield is required.
Further, the PLL circuit may lose phase synchronization momentarily due to switching noise, and it is necessary to install a noise source sufficiently away from a loop of the PLL synthesizer 21 through which a high-frequency current flows.
However, with the downsizing of the PLL frequency synthesizer module, that is, the high density mounting, the space for installing the shield plate, the gap between the electronic components constituting the PLL frequency synthesizer module, and the degree of freedom in the arrangement of the electronic components are lost. Conventional EMI measures cannot be taken.
The present invention has been made to solve the above problems,
It is an object of the present invention to provide a PLL frequency synthesizer module that satisfies EMI requirements and is compatible with miniaturization.
[0011]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the invention according to claim 1 according to the present invention provides:
A PLL frequency synthesizer module including a PLL circuit, an amplifier, an attenuator, a first low-pass filter, a switch, an external output terminal, and an external input terminal,
The external input terminal is connected to the input side of the PLL circuit, the output side of the PLL circuit is connected to the input side of the amplifier, the output side of the amplifier is connected to the input side of the attenuator, and the output of the attenuator is connected. And the input side of the low-pass filter is connected, the output side of the low-pass filter is connected to the input side of the switch, and the output side of the switch is connected to the external output terminal.
According to a second aspect of the present invention, in the first aspect,
The PLL circuit includes a voltage controlled oscillator, a power splitter, a PLL-IC, and a second low-pass filter,
The voltage-controlled oscillator, the power splitter, and the PLL-IC are sequentially and substantially linearly arranged along a first arrangement line.
According to a third aspect of the present invention, in the second aspect,
The amplifier, the attenuator, the first low-pass filter, the switch, and the external output terminal are arranged substantially in a straight line along a second arrangement line;
The first arrangement line and the second arrangement line are parallel to each other.
According to a fourth aspect of the present invention, in the third aspect,
The signal arrangement of the first arrangement line and the second arrangement line may be opposite to each other, so that the distance between the switch and the output of the voltage controlled oscillator is increased.
[0015]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on the illustrated embodiments of the present invention.
FIG. 1 is a block diagram of a PLL frequency synthesizer module according to an embodiment of the present invention.
A PLL circuit 5 including a PLL-IC1, a low-pass filter (LPF: second low-pass filter) 2, a voltage-controlled oscillator (VCO) 3, and a power splitter 4,
An amplifier 6 for amplifying the output of the VCO 3 divided by the power splitter 4,
An attenuator 7 for adjusting the output of the amplifier 6;
A low-pass filter (LPF: first low-pass filter) 8 for waveform shaping;
A switch 9 for turning on or off an output signal;
An external output terminal 10 and an external input terminal 11 are provided,
The external input terminal 11 connected to the external reference signal source 13 is connected to the input side of the PLL-IC1, the output side of the PLL-IC1 is connected to the input side of the LPF2, and the output side of the LPF2 is connected to the output side of the LPF2. The input side of the VCO 3 is connected, the output side of the VCO 3 is connected to the input side of the power splitter 4, one output side of the power splitter 4 is connected to the input side of the PLL-IC1, and the power splitter 4 is connected. Is connected to the input side of the amplifier 6, the output side of the amplifier 6 is connected to the input side of the attenuator 7, the output side of the attenuator 7 is connected to the input side of the LPF 8, and The output side of the LPF 8 is connected to the input side of the switch 9, and the output side of the switch 9 is connected to the external output terminal 10.
[0017]
The characteristic configuration of this embodiment is as follows.
Conventionally, a PLL synthesizer 21, an attenuator 22, an amplifier 23, a phase shifter 24, and a switch 25 are connected in this order.
That the LPF 8 is used instead of the phase shifter 24,
The amplifier 6 and the attenuator 7 are replaced in this order.
With such a configuration, miniaturization is possible without deteriorating EMI. The use of the LPF 8 also has the effect of improving the output frequency selection range.
FIG. 2 is a schematic diagram showing the arrangement of electronic components constituting the PLL frequency synthesizer module.
The VCO 3, the power splitter 4, and the PLL-IC1 are arranged substantially in a straight line along a first arrangement line L1 in the figure, and the amplifier 6, the attenuator 7, the LPF 8, the switch 9, the external output The terminals 11 are arranged substantially linearly along the second arrangement line L2 in the figure,
The first arrangement line L1 and the second arrangement line L2 are parallel.
Also,
By mounting the first array line L1 and the second array line L2 in opposite directions, the signals are mounted on the printed circuit board 12 so as to increase the distance between the switch 9 and the output of the VCO 3. .
With such a configuration, it is possible to provide a PLL frequency synthesizer module that can be reduced in size while taking measures against EMI.
[0020]
According to the first to fourth aspects of the present invention, an output frequency selectivity is improved by using an LPF instead of the conventional phase shifter.
Further, by connecting the switch between the external output terminal and the attenuator, and by arranging the switch alternately with the output side of the VCO, the phase synchronization is not instantaneously lost due to the switching noise, so that a noise source can be provided. This has the effect that the switch is sufficiently separated from the loop of the PLL circuit.
As described above, there is an effect that the conventional EMI countermeasures such as installation of the shield and widening the gap between the electronic components constituting the PLL frequency synthesizer module are not required.
[Brief description of the drawings]
FIG. 1 is a block diagram of a PLL frequency synthesizer module according to an embodiment of the present invention.
FIG. 2 is a schematic view of a component arrangement of a PLL frequency synthesizer module according to an embodiment of the present invention.
FIG. 3 is a configuration diagram of a conventional PLL frequency synthesizer module.
(A) Block diagram.
(B) Schematic diagram of component arrangement.
[Explanation of symbols]
1: PLL-IC 2: Low-pass filter (LPF)
DESCRIPTION OF SYMBOLS 3 ... Voltage controlled oscillator (VCO) 4 ... Power splitter 5 ... PLL circuit 6 ... Amplifier 7 ... Attenuator 8 ... Low pass filter (LPF) 9 ... Switch 10 ... External output terminal 11 ... External input terminal 12 ... Printed wiring board 13 ... External Reference signal source 21 PLL synthesizer 22 Attenuator 23 Buffer amplifier 24 Phase shifter 25 Switch 26 Output terminal 30 Printed wiring board 31 Metal frames 31a and 31b Shield wall L1 First arrangement line L2 First 2 array lines

Claims (4)

A PLL frequency synthesizer module including a PLL circuit, an amplifier, an attenuator, a first low-pass filter, a switch, an external output terminal, and an external input terminal,
The external input terminal is connected to the input side of the PLL circuit, the output side of the PLL circuit is connected to the input side of the amplifier, the output side of the amplifier is connected to the input side of the attenuator, and the output of the attenuator is connected. Wherein the output side of the low-pass filter is connected to the input side of the switch, the output side of the low-pass filter is connected to the input side of the switch, and the output side of the switch is connected to the external output terminal. Frequency synthesizer module. The PLL circuit includes a voltage controlled oscillator, a power splitter, a PLL-IC, and a second low-pass filter,
2. The PLL frequency synthesizer module according to claim 1, wherein said voltage-controlled oscillator, said power splitter, and said PLL-IC are sequentially arranged in a substantially straight line along a first arrangement line. The amplifier, the attenuator, the first low-pass filter, the switch, and the external output terminal are arranged substantially in a straight line along a second arrangement line,
3. The PLL frequency synthesizer module according to claim 2, wherein the first arrangement line and the second arrangement line are parallel. The signal arrangement of the first arrangement line and the second arrangement line is made opposite to each other so as to increase the distance between the switch and the output of the voltage controlled oscillator. 3. The PLL frequency synthesizer module according to 3.

Images