JPH01137719A - Filter circuit - Google Patents
Filter circuitInfo
- Publication number
- JPH01137719A JPH01137719A JP29692487A JP29692487A JPH01137719A JP H01137719 A JPH01137719 A JP H01137719A JP 29692487 A JP29692487 A JP 29692487A JP 29692487 A JP29692487 A JP 29692487A JP H01137719 A JPH01137719 A JP H01137719A
- Authority
- JP
- Japan
- Prior art keywords
- filter
- phase
- delay
- frequency
- characteristic
- 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.)
- Pending
Links
- 239000003990 capacitor Substances 0.000 claims abstract description 7
- 230000001419 dependent effect Effects 0.000 claims 1
- 238000010586 diagram Methods 0.000 description 7
- 230000010363 phase shift Effects 0.000 description 5
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
Landscapes
- Networks Using Active Elements (AREA)
Abstract
Description
【発明の詳細な説明】
産業上の利用分野
本発明は、シリコンウェハー上などに形成するモノリシ
ックＩＣ内にフィルタを集積化する場合に適したフィル
タ回路に関するものである。DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a filter circuit suitable for integrating a filter into a monolithic IC formed on a silicon wafer or the like.
従来の技術
電気回路の集積化が進むにつれて、外付のブロック・フ
ィルタのＩＣ化が、回路の小型化、低コスト化を実現す
る上での重要な課題となっている。従来のフィルタにお
いては、大部分が、インダクタンスし、容量Ｃ１抵抗Ｒ
で構成されているが、インダクタンスしは、ＩＣ化がむ
すかしく、ＩＣ化フィルタには、Ｃ，Ｈのみで構成可能
なアクティブ・フィルタが適している。−数的に、フィ
ルタの特性としては、次の点が要求される。2. Description of the Related Art As the integration of electric circuits progresses, the use of ICs for external block filters has become an important issue in achieving miniaturization and cost reduction of circuits. In conventional filters, most of them are inductance, capacitance C1, resistance R
However, it is difficult to integrate the inductance into an IC, so an active filter that can be configured with only C and H is suitable as an IC filter. - Numerically, the following characteristics of the filter are required.
（１） 通過域は、平坦で偏差が少ないこと。(1) The passing zone must be flat and have little deviation.
（２） 減衰域は、しゃ所持性が急峻で、減衰量が大
きいこと。(2) The attenuation region should have a steep barrier property and a large amount of attenuation.
（３）通過域の位相特性は、周波数に対して直線的に変
化すること。すなわち、位゛相を角周波数で微分した、
遅延特性が平坦なこと。(3) The phase characteristics of the passband should change linearly with frequency. In other words, the phase is differentiated by the angular frequency,
Flat delay characteristics.
第４図は、２次低域通過フィルタとしてよく用いられる
正帰環型フィルタであり、しゃ断層波数ｆ０は、次式で
表わされる。FIG. 4 shows a positive feedback filter that is often used as a second-order low-pass filter, and the cutoff layer wave number f0 is expressed by the following equation.
発明が解決しようとする問題点
抵抗及び容量値によりバタワース特性、ベッセル特性等
、各種の伝達関数を持ったフィルタを構成することがで
きるが、上記、フィルタとして要求される特性的な面か
ら見ると、バタワース特性を持つフィルタは、しゃ断特
性は、急峻であるが、遅延特性が通過域で大きなリヅブ
ルを生ずる。一方、ベッセル特性を持つフィルタは、通
過域での遅延特性が平坦となるが、振幅特性がゆるやか
で、切れ味が悪くなる。以上のように、フィルタとして
要求される点を同時に、満足することが困難であるとい
う問題点があった。Problems to be Solved by the Invention Filters with various transfer functions such as Butterworth characteristics and Bessel characteristics can be constructed depending on the resistance and capacitance values, but from the viewpoint of the characteristics required for the filter as described above, , a filter with Butterworth characteristics has a steep cutoff characteristic, but its delay characteristic causes large ripples in the passband. On the other hand, a filter with Bessel characteristics has a flat delay characteristic in the passband, but has a gentle amplitude characteristic and is not sharp. As mentioned above, there is a problem in that it is difficult to simultaneously satisfy the requirements of a filter.
本発明の目的は、上記した従来の欠点をなくし、フィル
タとして要求される特性を満足したフィルタ集積回路を
提供することにある。SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned conventional drawbacks and to provide a filter integrated circuit that satisfies the characteristics required for a filter.
問題点を解決するための手段
上記目的を達成するため、本発明は、全周波数域で振幅
特性が一定で位相特性が周波数の関係となる移相回路を
アクティブ・フィルタに付加したものである。Means for Solving the Problems In order to achieve the above object, the present invention adds to an active filter a phase shift circuit whose amplitude characteristics are constant over the entire frequency range and whose phase characteristics are related to frequency.
作用
本発明によると、しゃ断特性が急峻で、通過域の位相特
性に欠点のあるアクティブ・フィルタの遅延特性を補正
して平坦な遅延特性を実現することができる。According to the present invention, it is possible to realize a flat delay characteristic by correcting the delay characteristic of an active filter that has a sharp cut-off characteristic and a defective phase characteristic in the passband.
実施例
以下、本発明を第１図の実施例装置の回路図により説明
する。EXAMPLE The present invention will be explained below with reference to the circuit diagram of the embodiment device shown in FIG.
同図の回路において、Ｒ１，Ｒ２，Ｒ１＋ Ｒ４１Ｒ５
は抵抗、ＣＩｌ Ｃ２，Ｃ３はコンデンサ、１は、ゲイ
ンがＫの演算増幅器、２は、演算増幅器である。この回
路は、要するに、抵抗Ｒ，，Ｒ２、コンデンサｃ１．ｃ
２及び、ゲインがＫの演算増幅器１から成る２次低域通
過フィルタに、抵抗Ｒ３。In the circuit of the same figure, R1, R2, R1+ R41R5
is a resistor, CIl C2 and C3 are capacitors, 1 is an operational amplifier with a gain of K, and 2 is an operational amplifier. In short, this circuit consists of resistors R,, R2, capacitors c1. c.
2 and a second-order low-pass filter consisting of an operational amplifier 1 with a gain of K, and a resistor R3.
Ｒ４，Ｒ５、コンデンサＣ３及び、演算増幅器２から成
る移相回路を付加したものである。低域通過フィルタの
しゃ断特性を急峻にすると、遅延特性が、平坦でなくな
る。そこで移相特性が、次式で表わされる移相回路を直
列に接続することにより、通過域の遅延特性を平坦なも
のとしている。A phase shift circuit consisting of R4, R5, a capacitor C3, and an operational amplifier 2 is added. If the cut-off characteristic of the low-pass filter is made steep, the delay characteristic will not be flat. Therefore, by connecting phase shift circuits in series whose phase shift characteristic is expressed by the following equation, the delay characteristic of the passband is flattened.
ｆ＝２ｊａｎ−’ （２πｆＣ３Ｒ）
（ただし、Ｒｓ −Ｒ４＝ Ｒｓ ＝ Ｒ）第２図はこ
の実施例装置のブロック構成図であり、第３図はそのそ
れぞれのブロックの遅延特性および全体の遅延特性図で
ある。この実施例装置によると、しゃ断特性は、急峻だ
が、遅延特性が平坦でない低域通過フィルタ３の遅延特
性５を移相回路４の周波数増に依存して低域する遅延特
性６により補正して、通過域での遅延特性を平坦化して
、全体の遅延特性７は、平坦、かつ急峻しゃ断特性にな
っている。f=2jan-' (2πfC3R) (Rs -R4= Rs = R) Fig. 2 is a block diagram of the device of this embodiment, and Fig. 3 shows the delay characteristics of each block and the overall delay characteristic. It is a diagram. According to the device of this embodiment, the delay characteristic 5 of the low-pass filter 3, which has a steep cut-off characteristic but whose delay characteristic is not flat, is corrected by the delay characteristic 6 of the phase shift circuit 4, which has a low frequency depending on the frequency increase. , the delay characteristic in the passband is flattened, and the overall delay characteristic 7 is flat and has a steep cut-off characteristic.
発明の効果
本発明のフィルタ回路によると、急峻なしゃ断特性を持
ち、通過域での遅延特性が、平坦な特性を持ったフィル
タを実現できる。これにより出力に到着する入力の各周
波数成分が、揃い、波形を歪ませることな（伝送するこ
とができる。Effects of the Invention According to the filter circuit of the present invention, it is possible to realize a filter having steep cutoff characteristics and flat delay characteristics in the passband. As a result, each frequency component of the input that arrives at the output is aligned and can be transmitted without distorting the waveform.
第１図は、本発明の一実施例装置の回路図、第２図およ
び第３図は、本発明の一実施例を示すブロック図と、そ
の遅延特性図、第４図は、２次の正帰環型低域通過フィ
ルタの従来例回路図である。
Ｒ＋ ＊ Ｒ２ｒ Ｒ３，Ｒ４、Ｒｓ・・・・・・抵抗
、ＣＩｌ Ｃ２＋Ｃ３・・・・・・コンデンサ、１・・
・・・・ゲインにの演算増幅器、２・・・・・・演算増
幅器。
代理人の氏名 弁理士 中尾敏男 ほか１名第１図
第２図
第３図
一周シズ数
第４図
Ｃ３FIG. 1 is a circuit diagram of a device according to an embodiment of the present invention, FIGS. 2 and 3 are block diagrams showing an embodiment of the present invention and their delay characteristic diagrams, and FIG. FIG. 2 is a circuit diagram of a conventional example of a positive feedback low-pass filter. R+ * R2r R3, R4, Rs...Resistor, CIl C2+C3...Capacitor, 1...
...Operation amplifier for gain, 2...Operation amplifier. Name of agent: Patent attorney Toshio Nakao and one other person Figure 1 Figure 2 Figure 3 Number of rounds per round Figure 4 C3
Claims (1)
で振幅特性が一定、かつ、位相特性が周波数依存の関係
になった移相回路をアクティブ・フィルタに付加したこ
とを特徴とするフィルタ回路。A filter circuit comprising a resistor, a capacitor, and a transistor, and is characterized in that a phase shifting circuit is added to an active filter, and the amplitude characteristic is constant over the entire frequency range, and the phase characteristic is frequency dependent.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP29692487A JPH01137719A (en) | 1987-11-24 | 1987-11-24 | Filter circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP29692487A JPH01137719A (en) | 1987-11-24 | 1987-11-24 | Filter circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH01137719A true JPH01137719A (en) | 1989-05-30 |
Family
ID=17839940
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP29692487A Pending JPH01137719A (en) | 1987-11-24 | 1987-11-24 | Filter circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH01137719A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2001003352A1 (en) * | 1999-07-05 | 2001-01-11 | Jamming Electronic Co., Ltd. | Jammer |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS60169213A (en) * | 1984-02-13 | 1985-09-02 | Murata Mfg Co Ltd | All pass filter |
-
1987
- 1987-11-24 JP JP29692487A patent/JPH01137719A/en active Pending
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS60169213A (en) * | 1984-02-13 | 1985-09-02 | Murata Mfg Co Ltd | All pass filter |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2001003352A1 (en) * | 1999-07-05 | 2001-01-11 | Jamming Electronic Co., Ltd. | Jammer |
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