JPS6351576B2 - - Google Patents
Info
- Publication number
- JPS6351576B2 JPS6351576B2 JP13908381A JP13908381A JPS6351576B2 JP S6351576 B2 JPS6351576 B2 JP S6351576B2 JP 13908381 A JP13908381 A JP 13908381A JP 13908381 A JP13908381 A JP 13908381A JP S6351576 B2 JPS6351576 B2 JP S6351576B2
- Authority
- JP
- Japan
- Prior art keywords
- circuit
- operational amplifier
- band
- constant
- resistor
- 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
Links
- 239000003990 capacitor Substances 0.000 claims description 10
- 230000003321 amplification Effects 0.000 description 4
- 238000003199 nucleic acid amplification method Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 238000004458 analytical method Methods 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
Landscapes
- Networks Using Active Elements (AREA)
- Amplifiers (AREA)
- Input Circuits Of Receivers And Coupling Of Receivers And Audio Equipment (AREA)
Description
【発明の詳細な説明】
本発明は、同調周波数が変つても増幅帯域が変
らないようにした高周波同調回路に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high frequency tuning circuit in which the amplification band does not change even if the tuning frequency changes.
高周波帯で比較的受信周波数帯域が広い受信装
置例えばAM波放送帯受信機等では、Ｑ＝一定の
傾向を持つので下限周波数帯では増幅帯域が狭
く、上限周波数帯ではこれが広くなり（利得は前
者が大、後者が小）、忠実度と雑音特性が変動す
ることになる。本発明はこれを改善し、RF帯の
広い帯域に亘つて中心周波数が変つても増幅帯域
一定となる高周波同調回路を提供しようとするも
のである。次に図面を参照しながら説明する。 In a receiving device that has a relatively wide reception frequency band in the high frequency band, such as an AM wave broadcast band receiver, Q has a constant tendency, so the amplification band is narrow in the lower limit frequency band, and widen in the upper limit frequency band (the gain is in the former (the former is large and the latter is small), the fidelity and noise characteristics will vary. The present invention aims to improve this and provide a high frequency tuning circuit in which the amplification band remains constant even if the center frequency changes over a wide RF band. Next, explanation will be given with reference to the drawings.
帯域一定で中心周波数だけを変える回路は低周
波のフイルタ回路などで知られている。第１図は
その一例で、演算増幅器（オペアンプ）OP、抵
抗Ra〜Rc、コンデンサCa，Cbを図示の如く接
続してなり、バンドパスフイルタの特性を有す
る。即ち概略的にはコンデンサCbがハイパス素
子、コンデンサCaがハ抑制素子となり、抵抗Ra
〜Rcと共に作る時定数従つて遮断周波数を適当
に選べばバンドパスとなる訳である。この回路で
は抵抗Rbを可変抵抗としてこれを変えると、帯
域は一定、利得も一定で、中心周波数だけを変え
ることができる。但し、これにはRa≫Rbの条件
があり、RF帯ではこれを実現することが困難で
ある。即ち動作が不安定になつたり、Ｓ／Ｎが悪
化したりする。Ra≫Rbの条件が充分成立しなけ
れば、上記の帯域、利得は一定、中心周波数のみ
変化、は近似的にしか成立しない。 Circuits that keep the band constant and only change the center frequency are known as low-frequency filter circuits. FIG. 1 shows an example of this, in which an operational amplifier OP, resistors Ra to Rc, and capacitors Ca and Cb are connected as shown, and has the characteristics of a bandpass filter. In other words, roughly speaking, capacitor Cb is a high-pass element, capacitor Ca is a suppression element, and resistor Ra
If the time constant created with ~Rc and the cutoff frequency are appropriately selected, it becomes a bandpass. In this circuit, the resistor Rb is a variable resistor, and by changing it, the band is constant, the gain is constant, and only the center frequency can be changed. However, this requires the condition that Ra≫Rb, which is difficult to achieve in the RF band. That is, the operation becomes unstable or the S/N ratio deteriorates. Unless the condition Ra≫Rb is sufficiently satisfied, the above-mentioned band and gain are constant, and only the center frequency changes, which only approximately holds true.
第２図はbi−quad型フイルタ回路と呼ばれる
回路で、オペアンプOP1〜OP3、抵抗R1〜R6、コ
ンデンサC1，C2を図示の如く接続してなる。こ
の回路の解析結果は「アクテイブフイルタの設
計」（電子科学シリーズ52、pp147）などの文献
に記載されているが、二次帯域通過型フイルタの
入力IN、出力OUT間の伝達関数の一般式Ｔ（Ｓ）
は
Ｔ（Ｓ）＝Ｈω0／ＱＳ／S2＋ω0／ＱＳ＋ωo2…
…(1)
で表わされる。一方、第２図の回路で入力電圧
V1に対する出力電圧V2を求めてみると、
V2／V1＝−１／R4C1Ｓ／S2＋１／R1C1Ｓ＋１／R2R3C1C2
・R6／R5……(2)
となる。従つて次式が成立する。 FIG. 2 shows a circuit called a bi-quad type filter circuit, in which operational amplifiers OP 1 to OP 3 , resistors R 1 to R 6 , and capacitors C 1 and C 2 are connected as shown. The analysis results of this circuit are described in literature such as "Design of Active Filters" (Electronic Science Series 52, pp147), but the general formula for the transfer function between the input IN and output OUT of a secondary bandpass filter is T (S)
is T(S)=Hω 0 /QS/S 2 +ω 0 /QS+ωo 2 …
...(1) On the other hand, in the circuit shown in Figure 2, the input voltage
Determining the output voltage V 2 for V 1 , V 2 /V 1 = -1/R 4 C 1 S/S 2 +1/R 1 C 1 S + 1/R 2 R 3 C 1 C 2
・R 6 /R 5 ...(2). Therefore, the following equation holds.
こゝでR2＝R3＝R0、C1＝C2＝C0とすると、利
得Ｈ、中心角周波数ω0、バンド幅Δωは次の如く
なる。 Here, when R 2 =R 3 =R 0 and C 1 =C 2 =C 0 , the gain H, central angular frequency ω 0 , and bandwidth Δω are as follows.
Ｈ＝−R1／R4 ……(4)
Δω＝ω0／Ｑ＝１／R1C0 ……(6)
これらの(4)、(5)、(6)式から、C0，R1，R4を一
定に保ち、R5とR6を変えれば（従来回路ではR5
＝R6＝一定）、Δω、Ｈは一定でω0のみ変えるこ
とができる。抵抗R5とR6はその比がω0に影響す
るから、一方を固定して他方を変化させてもよい
が、一方が増加するとき他方は減少するように変
化させると、いわばプツシユプル型の動作とな
り、中心角周波数ω0を鋭敏、大幅に変えること
ができる。第３図にその調整部分を示す。抵抗
R5，R6は可変抵抗として構成され、その一端ａ
が前段増幅器OP2の出力端に、他端ｂが自段増幅
器OP3の出力端へ及び帰還抵抗R3を介して初段増
幅器OP1の入力端へ接続され、摺動子ｃが自段増
幅器OP3の入力端へ接続される。摺動子ｃを図面
左方へ移動させればR6／R5が大になり、同右方
へ移動させればR6／R5が小になる。前記(5)式に
示されるようにR6／R5はω0に対して平方根でし
か利かないが、この平方根でしか利かないという
点は従来回路も同様である。唯本回路では可変素
子がR5とR6の２つあるから、これらを逆方向に
増減することによりω0に対する利き方を強くす
ることができる。なおこれらの抵抗R5，R6とし
ては通常の抵抗器の他に、スイツチド キヤパシ
タ フイルタに見られる等価抵抗（スイツチド
キヤパシタ）を用いることができる。 H= -R1 / R4 ...(4) Δω=ω 0 /Q=1/R 1 C 0 ...(6) From these equations (4), (5), and (6), keeping C 0 , R 1 , and R 4 constant, and R 5 and If you change R 6 (in the conventional circuit, R 5
= R 6 = constant), Δω, and H are constant and only ω 0 can be changed. The ratio of resistors R 5 and R 6 affects ω 0 , so one can be fixed while the other is changed, but if one is changed so that when the other increases, the other decreases, a so-called push-pull type is created. The central angular frequency ω 0 can be changed sharply and significantly. Figure 3 shows the adjustment part. resistance
R 5 and R 6 are configured as variable resistors, one end a
is connected to the output terminal of the pre-stage amplifier OP 2 , the other end b is connected to the output terminal of the self-stage amplifier OP 3 and to the input end of the first stage amplifier OP 1 via the feedback resistor R 3 , and the slider c is connected to the output end of the self-stage amplifier OP 3. Connected to the input end of OP 3 . If the slider c is moved to the left in the drawing, R 6 /R 5 becomes larger, and if the slider c is moved to the right, R 6 /R 5 becomes smaller. As shown in the above equation (5), R 6 /R 5 is only effective as the square root of ω 0 , and the conventional circuit is also similar in that it is only effective as the square root. Since there are two variable elements R 5 and R 6 in the present circuit, by increasing or decreasing these in opposite directions, the effect on ω 0 can be made stronger. Note that these resistors R 5 and R 6 can be used in addition to ordinary resistors, as well as equivalent resistances found in switched capacitor filters (switched capacitor filters).
capacitor) can be used.
上述のように設定した第２図の回路は数ＭHz帯
でも利得を有し、ラジオ用高周波同調増幅器とし
て充分使用できる。そしてω0のみ変つて（詳し
くはＱも変る）、Ｈ，Δωは一定であるから、広
い放送周波数帯域に亘つて雑音混入などの恐れの
少ない、優れた増幅動性を示す。またこの回路で
はインダクタンスは使用しておらず、オペアンプ
とＲ，Ｃのみで構成されるからIC化が容易であ
る。 The circuit shown in FIG. 2, set as described above, has a gain even in the several MHz band, and can be used satisfactorily as a radio frequency tuned amplifier. Since only ω 0 changes (specifically, Q also changes) and H and Δω remain constant, excellent amplification performance is exhibited over a wide broadcasting frequency band with little risk of noise contamination. Furthermore, this circuit does not use inductance and is composed only of an operational amplifier, R, and C, making it easy to integrate into an IC.
以上説明したように本発明によれば、AM受信
機などの高周波回路に応用して全受信帯域で感
度、忠実度、雑音特性が平坦な優れた同調増幅回
路が得られる。 As explained above, according to the present invention, it is possible to obtain an excellent tuned amplifier circuit that is applied to a high frequency circuit such as an AM receiver and has flat sensitivity, fidelity, and noise characteristics over the entire reception band.
第１図は従来例を示す回路図、第２図は本発明
を適用する高周波同調回路を示す回路図、第３図
は本発明の要部を示す回路図である。図面でOP1
は第１の演算増幅器、OP2は第２の演算増幅器、
OP3は第３の演算増幅器である。
FIG. 1 is a circuit diagram showing a conventional example, FIG. 2 is a circuit diagram showing a high frequency tuning circuit to which the present invention is applied, and FIG. 3 is a circuit diagram showing essential parts of the present invention. OP 1 with drawings
is the first operational amplifier, OP 2 is the second operational amplifier,
OP3 is the third operational amplifier.
Claims (1)
列回路で構成される帰還回路を持つ第１の演算増
幅器、 入力抵抗R2と、コンデンサC2からなる帰還回
路を持つ第２の演算増幅器、および 入力抵抗R5と、抵抗R6からなる帰還回路を持
つ第３の演算増幅器を縦続接続し、かつ抵抗R3
により第３の演算増幅器の出力端から第１の演算
増幅器の入力端へ帰還を施した回路を備え、 前記抵抗R2，R3をR2＝R3＝R0とし、コンデン
サC1，C2をC1＝C2＝C0とし、かつC0，R1，R4を
一定として比R6／R5を可変としてなることを特
徴とする高周波同調回路。[Claims] 1. A first operational amplifier having a feedback circuit consisting of an input resistance R 4 and a parallel circuit of a resistance R 1 and a capacitor C 1 ; A feedback circuit consisting of an input resistance R 2 and a capacitor C 2 . A second operational amplifier having an input resistor R 5 and a third operational amplifier having a feedback circuit consisting of a resistor R 6 are connected in cascade, and a resistor R 3
The circuit includes a circuit that performs feedback from the output terminal of the third operational amplifier to the input terminal of the first operational amplifier, the resistors R 2 and R 3 are R 2 = R 3 = R 0 , and the capacitors C 1 and C 2 as C 1 =C 2 =C 0 , and with C 0 , R 1 , and R 4 constant, the ratio R 6 /R 5 is variable.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13908381A JPS5840935A (en) | 1981-09-03 | 1981-09-03 | High frequency tuning circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13908381A JPS5840935A (en) | 1981-09-03 | 1981-09-03 | High frequency tuning circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5840935A JPS5840935A (en) | 1983-03-10 |
| JPS6351576B2 true JPS6351576B2 (en) | 1988-10-14 |
Family
ID=15237082
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP13908381A Granted JPS5840935A (en) | 1981-09-03 | 1981-09-03 | High frequency tuning circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5840935A (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AU2631395A (en) * | 1994-06-13 | 1996-01-05 | Takeshi Ikeda | Tuned amplifier |
| AU3087395A (en) * | 1994-08-05 | 1996-03-04 | Takeshi Ikeda | Tuning amplifier |
| US6034566A (en) * | 1995-11-07 | 2000-03-07 | Takeshi Ikeda | Tuning amplifier |
| EP2584558B1 (en) | 2011-10-21 | 2022-06-15 | Harman Becker Automotive Systems GmbH | Active noise reduction |
| EP2667379B1 (en) | 2012-05-21 | 2018-07-25 | Harman Becker Automotive Systems GmbH | Active noise reduction |
| TWI511579B (en) * | 2013-09-30 | 2015-12-01 | C Media Electronics Inc | Headphone with active noise cancelling and auto-calibration method thereof |
-
1981
- 1981-09-03 JP JP13908381A patent/JPS5840935A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5840935A (en) | 1983-03-10 |
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