JPH022328B2 - - Google Patents
Info
- Publication number
- JPH022328B2 JPH022328B2 JP59085271A JP8527184A JPH022328B2 JP H022328 B2 JPH022328 B2 JP H022328B2 JP 59085271 A JP59085271 A JP 59085271A JP 8527184 A JP8527184 A JP 8527184A JP H022328 B2 JPH022328 B2 JP H022328B2
- Authority
- JP
- Japan
- Prior art keywords
- fdnr
- resistor
- capacitor
- resistors
- pass filter
- 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.)
- Expired - Lifetime
Links
- 239000003990 capacitor Substances 0.000 claims description 26
- 238000010586 diagram Methods 0.000 description 10
- 239000002131 composite material Substances 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 230000001419 dependent effect Effects 0.000 description 2
- 230000007423 decrease Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 238000000034 method Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H11/00—Networks using active elements
- H03H11/46—One-port networks
- H03H11/52—One-port networks simulating negative resistances
- H03H11/525—Simulating frequency dependent negative resistance [FDNR]
Landscapes
- Filters And Equalizers (AREA)
- Networks Using Active Elements (AREA)
Description
【発明の詳細な説明】
本発明は、周波数依存性の負性抵抗特性を呈す
るFDNR（Frequency Dependent Negative
Resistance）素子を用いたFDNR形ローパスフ
イルタに関する。DETAILED DESCRIPTION OF THE INVENTION The present invention provides a frequency dependent negative resistance (FDNR) exhibiting frequency dependent negative resistance characteristics.
This invention relates to an FDNR type low-pass filter using a Resistance element.
第１図は、従来のFDNR形ローパスフイルタ
を示す回路図であり、入力端子１と出力端子２間
に、並列接続されたコンデンサＣ１０と抵抗R0
そして抵抗Ｒ群とが直列接続され、直列接続され
た各抵抗Ｒ間の接続点に抵抗Ｒを介してFDNR
素子Ｄ１乃至Ｄ５が接続されている。且つ、出力
端子２と接地間には並列接続されたコンデンサＣ
１１と抵抗R0が接続されており、コンデンサＣ
１０とコンデンサＣ１１の容量は略等しく、並列
接続されたコンデンサＣ１０と抵抗R0の合成イ
ンピーダンスと、コンデンサＣ１１と抵抗R0の
合成インピーダンスが等しく設計されている等イ
ンピーダンス形のFDNR形ローパスフイルタで
ある。 FIG. 1 is a circuit diagram showing a conventional FDNR type low-pass filter, in which a capacitor C10 and a resistor R 0 are connected in parallel between input terminal 1 and output terminal 2.
Then, the resistor R group is connected in series, and the FDNR is connected to the connection point between each resistor R connected in series through the resistor R
Elements D1 to D5 are connected. In addition, a capacitor C is connected in parallel between the output terminal 2 and the ground.
11 and resistor R 0 are connected, and capacitor C
10 and capacitor C11 are approximately equal in capacity, and the combined impedance of capacitor C10 and resistor R0 connected in parallel is equal to the combined impedance of capacitor C11 and resistor R0 . .
従来、斯かるFDNR形ローパスフイルタは
FDNR素子を用いてインピーダンス・スケーリ
ング手法により、コイルを用いないローパスフイ
ルタを可能にしており、厳しい性能が要求される
デジタル・オーデオ用のフイルタとして多く使用
されている。しかし、第１図の如き従来の
FDNR形ローパスフイルタは、その入出力端部
にコンデンサＣ１０，Ｃ１１と抵抗値の大きい抵
抗R0が二つ接続され、且つ第２図に示すように
二つの演算増幅器Ａ１，Ａ２と四つの抵抗Ｒ５乃
至Ｒ８とコンデンサＣ３，Ｃ４から形成された
FDNR素子が接続されているので部品数が多く
なつて製造コストが高くなる欠点がある。 Conventionally, such an FDNR type low-pass filter
By using an impedance scaling method using an FDNR element, it is possible to create a low-pass filter that does not require a coil, and is often used as a filter for digital audio applications that require strict performance. However, the conventional
The FDNR type low-pass filter has capacitors C10 and C11 and two resistors R0 with a large resistance value connected to its input and output ends, and as shown in Fig. 2, two operational amplifiers A1 and A2 and four resistors R5. formed from R8 and capacitors C3 and C4
Since the FDNR elements are connected, there is a drawback that the number of parts increases and the manufacturing cost increases.
本発明は上述のような欠点を改善する為になさ
れたもので、フイルタの周波数特性を劣化させる
ことなく、部品数を減少させることによつて製造
コストを下げることができるFDNR形ローパス
フイルタを提供することを目的とする。 The present invention has been made to improve the above-mentioned drawbacks, and provides an FDNR type low-pass filter that can reduce manufacturing costs by reducing the number of parts without deteriorating the frequency characteristics of the filter. The purpose is to
以下、本発明に就いて第３図乃至第６図に基づ
き説明する。 Hereinafter, the present invention will be explained based on FIGS. 3 to 6.
第３図のFDNR形ローパスフイルタは第１図
と同様に入力端子１，２間の合成インピーダンス
と出力端子２と接地間の合成インピーダンスが略
等しい関係にあり、各抵抗Ｒの接続点にFDNR
素子Ｄ６乃至Ｄ８が接続されている。これらの
FDNR素子は第５図の如きFDNR素子を用いる。
入出力端部に互いに等しい容量値のコンデンサＣ
５，Ｃ６が接続され、夫々に抵抗Ｒ１が並列に接
続されており、コンデンサＣ５、抵抗Ｒ１とコン
デンサＣ６、抵抗Ｒ１の夫々の合成インピーダン
スは等しく設計されている。因に抵抗Ｒ１はフイ
ルタの低域での周波数特性の劣化を防止する為に
接続されており、入力端子１，２間の直列接続さ
れた抵抗Ｒの合成抵抗値の15倍以上の高抵抗が接
続されている。斯かるFDNR形ローパスフイル
タは信号入力段に大きなインピーダンス素子が接
続されるので、第６図の周波数特性図はイに示す
ように、減衰量が約−6dB低下する欠点がある。
又、第５図に示すような一個の演算増幅器Ａ等で
形成されたFDNR素子の場合、信号入力段にコ
ンデンサＣ５が接続されている為に、低い周波数
領域で入力インピーダンスが大きくなり比較的低
域雑音が大きくなる欠点があり、第５図の如き
FDNR素子を用いることにより、かなり部品数
が低減できるものの、未だ改良の余地があつた。 In the FDNR type low-pass filter shown in Figure 3, the composite impedance between input terminals 1 and 2 and the composite impedance between output terminal 2 and ground are approximately equal, as in Figure 1.
Elements D6 to D8 are connected. these
The FDNR element shown in FIG. 5 is used.
Capacitors C with equal capacitance at the input and output terminals
A resistor R1 is connected in parallel to each of the capacitors C5 and C6, and the combined impedance of the capacitor C5 and resistor R1 and the capacitor C6 and resistor R1 are designed to be equal. Incidentally, the resistor R1 is connected to prevent deterioration of the frequency characteristics of the filter in the low range, and the high resistance is 15 times or more the combined resistance value of the resistors R connected in series between input terminals 1 and 2. It is connected. Since such an FDNR type low-pass filter has a large impedance element connected to the signal input stage, it has the disadvantage that the attenuation decreases by about -6 dB, as shown in A in the frequency characteristic diagram of FIG.
In addition, in the case of an FDNR element formed by a single operational amplifier A, etc. as shown in Fig. 5, since a capacitor C5 is connected to the signal input stage, the input impedance becomes large in the low frequency region and becomes relatively low. It has the disadvantage of increasing noise in the area, as shown in Figure 5.
Although the number of components could be reduced considerably by using the FDNR element, there was still room for improvement.
第４図は本発明に係る７次のFDNR形ローパ
スフイルタの一実施例である。入力端子１と出力
端子２間に抵抗Ｒ６乃至Ｒ９が直列接続され、こ
れらの抵抗の接続点に第５図に示したFDNR素
子Ｄ１０，Ｄ１１，Ｄ１２が接続され、出力端子
２に並列接続されたコンデンサＣ７と抵抗Ｒ１０
が接続されており、抵抗Ｒ６〜Ｒ９の合成インピ
ーダンスと並列接続されたコンデンサＣ７、抵抗
Ｒ１０の合成インピーダンスとは不等関係に設計
される。第４図のFDNR形ローパスフイルタに
用いられるFDNR素子は、第５図に示すように
演算増幅器Ａとその非反転入力端子に抵抗Ｒ１と
コンデンサＣ１が接続され、コンデンサＣ１の他
端にコンデンサＣ２が接続されてその他端が接地
され、コンデンサＣ１とＣ２との接続点に抵抗Ｒ
３が接続され、演算増幅器Ａの反転入力端子に抵
抗Ｒ２とＲ４が接続され、抵抗Ｒ３とＲ４の他端
が演算増幅器Ａの出力端に接続され、抵抗Ｒ１と
Ｒ２の他端が入力端子４に接続されている。 FIG. 4 shows an embodiment of a seventh-order FDNR type low-pass filter according to the present invention. Resistors R6 to R9 are connected in series between input terminal 1 and output terminal 2, and FDNR elements D10, D11, and D12 shown in FIG. 5 are connected to the connection points of these resistors, and are connected in parallel to output terminal 2. Capacitor C7 and resistor R10
are connected, and the combined impedance of the resistors R6 to R9 and the combined impedance of the capacitor C7 and the resistor R10 connected in parallel are designed to have an unequal relationship. As shown in FIG. 5, the FDNR element used in the FDNR type low-pass filter shown in FIG. connected and the other end is grounded, and a resistor R is connected to the connection point between capacitors C1 and C2.
3 is connected, resistors R2 and R4 are connected to the inverting input terminal of operational amplifier A, the other ends of resistors R3 and R4 are connected to the output terminal of operational amplifier A, and the other ends of resistors R1 and R2 are connected to input terminal 4. It is connected to the.
本発明に係るFDNR形ローパスフイルタの第
４図の実施例によれば、入力端子１と出力端子２
間に直列接続された抵抗の合成抵抗値は45KΩに
対しコンデンサＣ７と並列接続された抵抗Ｒ１０
の抵抗値は約1500KΩ乃至2MΩであり、コンデン
サＣ７は約1000pFである。抵抗Ｒ１０の抵抗値
は直列接続された抵抗Ｒ６乃至Ｒ９の合成抵抗値
の20〜30倍の範囲で設定される。この時の、周波
数特性は、第６図のロに示すように、フイルタ特
性が低周波数（1KHz）から遮断周波数域（13K
Hz）付近までの周波数特性が零に近く極めて良好
な特性を得ることができた。又、出力端に接続さ
れた抵抗Ｒ１０は低域の振幅特性が持ち上げるの
を抑える効果がある。第６図のハは抵抗Ｒ１０が
無い場合の1KHz近傍の振幅特性を示す図であり、
振幅特性が持ち上がることを示している。従つ
て、出力端部に接続された抵抗Ｒ１０は1KHz近
傍の振幅特性が持ち上がるのを抑え、帯域内リツ
プルを最小に設定することが可能である。 According to the embodiment of the FDNR type low-pass filter according to the present invention shown in FIG.
The combined resistance value of the resistors connected in series between them is 45KΩ, and the resistor R10 connected in parallel with the capacitor C7
The resistance value of the capacitor C7 is about 1500KΩ to 2MΩ, and about 1000pF. The resistance value of the resistor R10 is set in the range of 20 to 30 times the combined resistance value of the resistors R6 to R9 connected in series. At this time, the frequency characteristics of the filter range from the low frequency (1KHz) to the cut-off frequency range (13KHz), as shown in Figure 6B.
Hz), the frequency characteristics were close to zero, and extremely good characteristics could be obtained. Furthermore, the resistor R10 connected to the output terminal has the effect of suppressing the increase in the amplitude characteristics in the low range. C in Fig. 6 is a diagram showing the amplitude characteristics near 1KHz when there is no resistor R10,
This shows that the amplitude characteristics are improved. Therefore, the resistor R10 connected to the output terminal can suppress the rise in amplitude characteristics near 1 KHz, and can set the in-band ripple to a minimum.
本発明に係るFDNR形ローパスフイルタは、
入力端子１と出力端子２間に直列接続された抵抗
群と、その抵抗群の各抵抗間に接続された
FDNR素子と、出力端子２と接地間に並列接続
されたコンデンサＣ７と抵抗Ｒ１０からなる
FDNR形ローパスフイルタであつて、FDNR素
子が第５図の如き構成であり、且つ入力端子１と
出力端子２間に直列接続された抵抗群の合成イン
ピーダンスと出力端子２と接地間に並列接続され
たコンデンサＣ７と抵抗Ｒ１０の合成インピーダ
ンスが不等関係である。斯かるFDNR形ローパ
スフイルタは従来のFDNR形ローパスフイルタ
と比較して部品数の低減が可能であり、製造コス
トの引き下げが可能となり極めて効果的な
FDNR形ローパスフイルタを提供できる。 The FDNR type low-pass filter according to the present invention is
A group of resistors connected in series between input terminal 1 and output terminal 2, and a resistor connected between each resistor of that group of resistors.
Consists of FDNR element, capacitor C7 and resistor R10 connected in parallel between output terminal 2 and ground.
This is an FDNR type low-pass filter, in which the FDNR element has a configuration as shown in Fig. 5, and the composite impedance of a group of resistors connected in series between input terminal 1 and output terminal 2, and the combined impedance of a resistor group connected in parallel between output terminal 2 and ground. The combined impedance of the capacitor C7 and the resistor R10 is unequal. This type of FDNR low-pass filter can reduce the number of parts compared to the conventional FDNR-type low-pass filter, making it possible to reduce manufacturing costs and making it extremely effective.
We can provide FDNR type low pass filter.
第１図は従来のFDNR形ローパスフイルタを
示す回路図であり、第２図はFDNR素子の一例
を示す回路図であり、第３図は本発明のFDNR
形ローパスフイルタを説明するための回路図であ
る。第４図は本発明のFDNR形ローパスフイル
タの一実施例を説明するための回路図であり、第
５図は本発明のFDNR形ローパスフイルタに用
いられるFDNR素子の回路図であり、第６図は
本発明のFDNR形ローパスフイルタの周波数特
性を説明するための図である。
Ｄ１乃至Ｄ５，Ｄ１０乃至Ｄ１２：FDNR素
子、Ａ，Ａ１，Ａ２：演算増幅器。
Fig. 1 is a circuit diagram showing a conventional FDNR type low-pass filter, Fig. 2 is a circuit diagram showing an example of an FDNR element, and Fig. 3 is a circuit diagram showing an example of an FDNR element.
FIG. 2 is a circuit diagram for explaining a type low-pass filter. FIG. 4 is a circuit diagram for explaining one embodiment of the FDNR type low-pass filter of the present invention, FIG. 5 is a circuit diagram of an FDNR element used in the FDNR type low-pass filter of the present invention, and FIG. FIG. 2 is a diagram for explaining the frequency characteristics of the FDNR type low-pass filter of the present invention. D1 to D5, D10 to D12: FDNR elements, A, A1, A2: operational amplifiers.
Claims (1)
抵抗群と、該抵抗群の各抵抗間と接地間に接続さ
れたFDNR素子と、該出力端子２と接地間に並
列接続されたコンデンサＣ７と抵抗Ｒ１０からな
るFDNR形ローパスフイルタであつて、該
FDNR素子が、演算増幅器Ａとその非反転入力
端子に抵抗Ｒ１とコンデンサＣ１が接続され、該
コンデンサＣ１の他端にコンデンサＣ２が接続さ
れてその他端が接地され、該コンデンサＣ１とＣ
２との接続点に抵抗Ｒ３が接続され、該演算増幅
器Ａの反転入力端子に抵抗Ｒ２とＲ４が接続さ
れ、該抵抗Ｒ３とＲ４の他端が該演算増幅器Ａの
出力端子に接続され、該抵抗Ｒ１とＲ２の他端が
入力端子４に接続されてなるものであることを特
徴とするFDNR形ローパスフイルタ。 ２ 入力端子１と出力端子２間に直列接続された
抵抗群の合成インピーダンスと該出力端子２と接
地間に並列接続された抵抗Ｒ１０とコンデンサＣ
７の合成インピーダンスが不等関係にある特許請
求の範囲第１項記載のFDNR形ローパスフイル
タ。[Claims] 1. A group of resistors connected in series between an input terminal 1 and an output terminal 2, an FDNR element connected between each resistor of the resistor group and the ground, and a FDNR element connected between the output terminal 2 and the ground. It is an FDNR type low pass filter consisting of a capacitor C7 and a resistor R10 connected in parallel.
In the FDNR element, a resistor R1 and a capacitor C1 are connected to an operational amplifier A and its non-inverting input terminal, a capacitor C2 is connected to the other end of the capacitor C1, and the other end is grounded, and the capacitors C1 and C1 are connected to each other.
2, resistors R2 and R4 are connected to the inverting input terminal of the operational amplifier A, and the other ends of the resistors R3 and R4 are connected to the output terminal of the operational amplifier A. FDNR type low-pass filter characterized in that the other ends of resistors R1 and R2 are connected to input terminal 4. 2. Combined impedance of a group of resistors connected in series between input terminal 1 and output terminal 2, and resistor R10 and capacitor C connected in parallel between output terminal 2 and ground.
7. The FDNR type low-pass filter according to claim 1, wherein the combined impedances of the filters have an unequal relationship.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59085271A JPS60247314A (en) | 1984-04-27 | 1984-04-27 | Fdnr type low pass filter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59085271A JPS60247314A (en) | 1984-04-27 | 1984-04-27 | Fdnr type low pass filter |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS60247314A JPS60247314A (en) | 1985-12-07 |
| JPH022328B2 true JPH022328B2 (en) | 1990-01-17 |
Family
ID=13853901
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP59085271A Granted JPS60247314A (en) | 1984-04-27 | 1984-04-27 | Fdnr type low pass filter |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS60247314A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0349468Y2 (en) * | 1984-12-17 | 1991-10-22 |
-
1984
- 1984-04-27 JP JP59085271A patent/JPS60247314A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS60247314A (en) | 1985-12-07 |
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