JPH05218747A - Frequency modulator - Google Patents
Frequency modulatorInfo
- Publication number
- JPH05218747A JPH05218747A JP31878091A JP31878091A JPH05218747A JP H05218747 A JPH05218747 A JP H05218747A JP 31878091 A JP31878091 A JP 31878091A JP 31878091 A JP31878091 A JP 31878091A JP H05218747 A JPH05218747 A JP H05218747A
- Authority
- JP
- Japan
- Prior art keywords
- circuit
- controlled oscillator
- voltage controlled
- oscillator circuit
- rom
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Landscapes
- Transmitters (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明はＦＭ変調器に関し、特に
電圧制御発振回路によってＦＭ変調を行うマイクロ波送
信機用のＦＭ変調器に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an FM modulator, and more particularly to an FM modulator for a microwave transmitter that performs FM modulation by a voltage controlled oscillator circuit.
【０００２】[0002]
【従来の技術】従来のこの種のＦＭ変調器は、図２に示
すように、分周回路２と、位相比較回路３と、ループア
ンプ５と、ループフィルタ６および基準発振回路４とに
より位相同期ループを形成し、バラクタを使用した電圧
制御発振回路（ＶＣＯ）１の周波数を制御する制御電圧
Ｖｆを生成している。また、重畳回路７により制御電圧
Ｖｆにベースバンド信号Ｓｂを重畳してＦＭ変調を行っ
ている。2. Description of the Related Art A conventional FM modulator of this type includes a frequency dividing circuit 2, a phase comparing circuit 3, a loop amplifier 5, a loop filter 6, and a reference oscillating circuit 4, as shown in FIG. A synchronous loop is formed to generate a control voltage Vf for controlling the frequency of the voltage controlled oscillator circuit (VCO) 1 using a varactor. Further, the superimposing circuit 7 superimposes the baseband signal Sb on the control voltage Vf to perform FM modulation.
【０００３】ここで、分周回路２は、電圧制御発振回路
１の出力を発振周波数制御信号Ｃｆに応じて分周し、ま
た、位相比較回路３は、基準発振回路４からの基準信号
と分周回路２からの分周出力との位相を比較して位相差
に応じた電圧を出力し、更にループアンプ５およびルー
プフィルタ６は、位相比較回路３の出力を増幅して不要
信号成分を除去して制御電圧Ｖｆを生成している。Here, the frequency dividing circuit 2 divides the output of the voltage controlled oscillator circuit 1 according to the oscillation frequency control signal Cf, and the phase comparison circuit 3 divides the frequency of the output from the reference oscillator circuit 4. The phase of the frequency-divided output from the frequency divider circuit 2 is compared to output a voltage corresponding to the phase difference. Further, the loop amplifier 5 and the loop filter 6 amplify the output of the phase comparator circuit 3 to remove unnecessary signal components. Then, the control voltage Vf is generated.
【０００４】[0004]
【発明が解決しようとする課題】上述した従来のＦＭ変
調器では、電圧制御発振回路の制御電圧に対する発振周
波数の関係、すなわちｆ−Ｖ特性が、図３に示すよう
に、バラクタの特性に依存して直線的に変化しない。こ
のため、送信周波数を変更するために電圧制御発振回路
の動作点を変更した場合、ＦＭ変調度が変化してしまう
という問題点を有している。In the conventional FM modulator described above, the relationship between the oscillation frequency and the control voltage of the voltage controlled oscillation circuit, that is, the fV characteristic depends on the characteristic of the varactor as shown in FIG. And does not change linearly. Therefore, when the operating point of the voltage controlled oscillator circuit is changed to change the transmission frequency, there is a problem that the FM modulation degree changes.
【０００５】本発明の目的は、送信周波数を変更するた
めに電圧制御発振回路の動作点を変更しても、ＦＭ変調
度が変化しないＦＭ変調器を提供することにある。An object of the present invention is to provide an FM modulator whose FM modulation degree does not change even if the operating point of the voltage controlled oscillator circuit is changed to change the transmission frequency.
【０００６】[0006]
【課題を解決するための手段】本発明のＦＭ変調器は、
電圧制御発振回路に印加する制御電圧に変調信号を重畳
してＦＭ変調を行うＦＭ変調器であって、前記電圧制御
発振回路の制御電圧対発振周波数特性を基に予め設定さ
れたデータを記憶するＲＯＭと、このＲＯＭから読出し
た前記データに応じて前記変調信号のレベルを調整する
可変減衰回路とを備えて構成されている。The FM modulator of the present invention comprises:
An FM modulator that performs FM modulation by superimposing a modulation signal on a control voltage applied to a voltage controlled oscillator circuit, and stores preset data based on a control voltage-oscillation frequency characteristic of the voltage controlled oscillator circuit. It comprises a ROM and a variable attenuation circuit that adjusts the level of the modulation signal according to the data read from the ROM.
【０００７】[0007]
【実施例】次に本発明について図面を参照して説明す
る。The present invention will be described below with reference to the drawings.
【０００８】図１は本発明の一実施例を示すブロック図
であり、図２に示した従来のＦＭ変調器と相違するとこ
ろは、可変減衰回路８およびＲＯＭ９を設けたことであ
る。なお、同一のブロックには同一符号を付している。FIG. 1 is a block diagram showing an embodiment of the present invention. What is different from the conventional FM modulator shown in FIG. 2 is that a variable attenuation circuit 8 and a ROM 9 are provided. The same blocks are designated by the same reference numerals.
【０００９】さて、バラクタを使用した電圧制御発振回
路１の周波数を制御するために、電圧制御発振回路１の
出力を発振周波数制御信号Ｃｆに応じて分周する分周回
路２と、基準発振回路４からの基準信号と分周回路２か
らの分周出力との位相を比較する位相比較回路３と、ル
ープアンプ５およびループフィルタ６とで位相同期ルー
プを形成して、制御電圧Ｖｆを生成している。In order to control the frequency of the voltage controlled oscillator circuit 1 using a varactor, the frequency divider circuit 2 for dividing the output of the voltage controlled oscillator circuit 1 according to the oscillation frequency control signal Cf and the reference oscillator circuit. The phase comparison circuit 3 that compares the phase of the reference signal from the frequency division circuit 4 with the frequency division output from the frequency division circuit 2 and the loop amplifier 5 and the loop filter 6 form a phase locked loop to generate the control voltage Vf. ing.
【００１０】また、重畳回路７により、制御電圧Ｖｆに
可変減衰回路８を経由したベースバンド信号Ｓｂを重畳
し、電圧制御発振回路１へ供給してＦＭ変調を行ってい
る。Further, the superimposing circuit 7 superimposes the baseband signal Sb passed through the variable attenuating circuit 8 on the control voltage Vf and supplies it to the voltage controlled oscillator circuit 1 to perform FM modulation.
【００１１】ところで、ＲＯＭ９には、電圧制御発振回
路１のｆ−Ｖ特性、つまり制御電圧に対する発振周波数
の関係から算定したＦＭ変調感度の変化を補正するデー
タが予め記憶されており、電圧制御発振回路１の発振周
波数を設定する発振周波数制御信号Ｃｆに応じて該当す
るデータを読出す。可変減衰回路８は、ＲＯＭ９から読
出されるデータに応じてベースバンド信号Ｓｂのレベル
を調整する。By the way, the ROM 9 stores in advance the data for correcting the fV characteristic of the voltage controlled oscillation circuit 1, that is, the change in the FM modulation sensitivity calculated from the relationship between the oscillation frequency and the control voltage. The corresponding data is read according to the oscillation frequency control signal Cf that sets the oscillation frequency of the circuit 1. The variable attenuation circuit 8 adjusts the level of the baseband signal Sb according to the data read from the ROM 9.
【００１２】従って、電圧制御発振回路１の動作点を変
化させて送信周波数を変更する場合、電圧制御発振回路
１のＦＭ変調感度の変化を補正するデータが可変減衰回
路８へ送出されてベースバンド信号Ｓｂのレベルを補正
するので、ＦＭ変調度を一定にすることができる。Therefore, when the operating frequency of the voltage controlled oscillator circuit 1 is changed to change the transmission frequency, data for correcting the change in the FM modulation sensitivity of the voltage controlled oscillator circuit 1 is sent to the variable attenuator circuit 8 and is sent to the baseband. Since the level of the signal Sb is corrected, the FM modulation degree can be made constant.
【００１３】[0013]
【発明の効果】以上説明したように本発明によれば、電
圧制御発振回路のｆ−Ｖ特性を基に設定されたＦＭ変調
感度の変化を補正するデータを予め記憶するＲＯＭ、お
よびＲＯＭから送出されるデータに応じてベースバンド
信号のレベルを調整する可変減衰回路を設けることによ
り、送信周波数を変更するために電圧制御発振回路の動
作点を変化させても、電圧制御発振回路のＦＭ変調感度
は補正されるので、ＦＭ変調度を一定にできるという効
果を有している。As described above, according to the present invention, the ROM for preliminarily storing the data for correcting the change in the FM modulation sensitivity set based on the fV characteristic of the voltage controlled oscillator, and the transmission from the ROM. By providing a variable attenuation circuit that adjusts the level of the baseband signal according to the data to be transmitted, even if the operating point of the voltage controlled oscillator circuit is changed to change the transmission frequency, the FM modulation sensitivity of the voltage controlled oscillator circuit is changed. Is corrected, so that the FM modulation degree can be made constant.
【図１】本発明の一実施例を示すブロック図である。FIG. 1 is a block diagram showing an embodiment of the present invention.
【図２】従来のＦＭ変調器の一例を示すブロック図であ
る。FIG. 2 is a block diagram showing an example of a conventional FM modulator.
【図３】バラクタを使用した電圧制御発振回路のｆ−Ｖ
特性の一例を示す図である。FIG. 3 fV of a voltage controlled oscillator circuit using a varactor
It is a figure which shows an example of a characteristic.
１ 電圧制御発振回路（ＶＣＯ） ８ 可変減衰回路 ９ ＲＯＭ Ｃｆ 発振周波数制御信号 Ｖｆ 制御電圧 Ｓｂ ベースバンド信号 1 Voltage Controlled Oscillator (VCO) 8 Variable Attenuation Circuit 9 ROM Cf Oscillation Frequency Control Signal Vf Control Voltage Sb Baseband Signal
Claims (1)
変調信号を重畳してＦＭ変調を行うＦＭ変調器であっ
て、前記電圧制御発振回路の制御電圧対発振周波数特性
を基に予め設定されたデータを記憶するＲＯＭと、この
ＲＯＭから読出した前記データに応じて前記変調信号の
レベルを調整する可変減衰回路とを備えることを特徴と
するＦＭ変調器。1. An FM modulator for performing FM modulation by superimposing a modulation signal on a control voltage applied to a voltage controlled oscillator circuit, the FM modulator being preset based on a control voltage-oscillation frequency characteristic of the voltage controlled oscillator circuit. An FM modulator comprising: a ROM for storing the data, and a variable attenuation circuit for adjusting the level of the modulation signal according to the data read from the ROM.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31878091A JPH05218747A (en) | 1991-12-03 | 1991-12-03 | Frequency modulator |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31878091A JPH05218747A (en) | 1991-12-03 | 1991-12-03 | Frequency modulator |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH05218747A true JPH05218747A (en) | 1993-08-27 |
Family
ID=18102865
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP31878091A Withdrawn JPH05218747A (en) | 1991-12-03 | 1991-12-03 | Frequency modulator |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH05218747A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7936228B2 (en) | 2005-12-06 | 2011-05-03 | Rohm Co., Ltd. | Frequency modulator and FM transmission circuit using the same |
-
1991
- 1991-12-03 JP JP31878091A patent/JPH05218747A/en not_active Withdrawn
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7936228B2 (en) | 2005-12-06 | 2011-05-03 | Rohm Co., Ltd. | Frequency modulator and FM transmission circuit using the same |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A300 | Withdrawal of application because of no request for examination |
Free format text: JAPANESE INTERMEDIATE CODE: A300 Effective date: 19990311 |