JPH04183103A - Feedback circuit - Google Patents
Feedback circuitInfo
- Publication number
- JPH04183103A JPH04183103A JP31329390A JP31329390A JPH04183103A JP H04183103 A JPH04183103 A JP H04183103A JP 31329390 A JP31329390 A JP 31329390A JP 31329390 A JP31329390 A JP 31329390A JP H04183103 A JPH04183103 A JP H04183103A
- Authority
- JP
- Japan
- Prior art keywords
- feedback circuit
- source follower
- feedback
- amplifier
- transistor
- 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
- 238000002955 isolation Methods 0.000 abstract description 3
- 238000010586 diagram Methods 0.000 description 3
- 239000003990 capacitor Substances 0.000 description 1
Landscapes
- Amplifiers (AREA)
Abstract
Description
【発明の詳細な説明】 産業上の利用分野 本発明は、フィードバック回路に間する。[Detailed description of the invention] Industrial applications The present invention relates to a feedback circuit.
従来の技術
従来のフィードバック回路は、第２図番こ、示す様に、
増幅器の入力ＩＮ−出力ＯＵＴ間に抵抗Ｒ４を接続して
いた。Prior art The conventional feedback circuit is as shown in Figure 2.
A resistor R4 was connected between the input IN and the output OUT of the amplifier.
発明が解決しようとする課題
上述した従来のフィードバック回路は、フィードバック
回路内のアイソレーションはとれていない為に、フィー
ドバック回路自体が増幅器にとって重い負荷になるとい
う欠点がある。Problems to be Solved by the Invention The conventional feedback circuit described above has the disadvantage that the feedback circuit itself becomes a heavy load on the amplifier because the feedback circuit does not have isolation.
本発明は従来の上記実情に鑑みてなされたものであり、
従って本発明の目的は、従来の技術に内在する上記欠点
を解消することを可能とした新規なフィードバック回路
を提供することにある。The present invention has been made in view of the above-mentioned conventional situation,
SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a novel feedback circuit which makes it possible to overcome the above-mentioned drawbacks inherent in the prior art.
課題を解決するための手段
上記目的を達成する為に、本発明に係るフィードバック
回路は、ソースフォロワまたはエミッタフォロワを含む
負帰還回路を備えて構成される。Means for Solving the Problems In order to achieve the above object, a feedback circuit according to the present invention includes a negative feedback circuit including a source follower or an emitter follower.
実施例
次に本発明をその好ましい一実施例について図面を参照
して具体的に説明する。Embodiment Next, a preferred embodiment of the present invention will be specifically explained with reference to the drawings.
第１図は本発明の一実施例３示す回路構成図である。FIG. 1 is a circuit configuration diagram showing a third embodiment of the present invention.
第１図を参照するに、１役場幅器１１に対して、ソース
フォロワとして動作するトランジスタＱ２を含むフィー
ドバック回路１２が入力ｌＮ−１カ０ＬＩＴ間に接続さ
れている。ここでＱ３は定電流源として動作するトラン
ジスタである。ソースフォロワＱ２自体は、利得がほと
んどＯｄＢであるので、フィードバック量はフィードバ
ック抵抗Ｒ３によって決定される。Referring to FIG. 1, a feedback circuit 12 including a transistor Q2 operating as a source follower is connected between the inputs 1N-1 and 0LIT to the single-function amplifier 11. Here, Q3 is a transistor that operates as a constant current source. Since the source follower Q2 itself has a gain of almost OdB, the amount of feedback is determined by the feedback resistor R3.
しかしながら、ソースフォロワは約４０ｄＢ以上アイソ
レーションがとれ、入力インピーダンスも充分に高い為
に、１役場幅器１１にとっては軽い負荷であり、１役場
幅器１１の駆動能力を低下させない。 −
本発明の他の実施例として、ソースフォロワとして作動
するＦＦＴトランジスタＱ２の代わりにバイポーラトラ
ンジスタをエミッタフォロワとして使用しても同様の効
果が得られる。However, since the source follower has an isolation of about 40 dB or more and has a sufficiently high input impedance, it is a light load on the single-office widening device 11 and does not reduce the driving capability of the single-office widening device 11. - In another embodiment of the invention, a similar effect can be obtained by using a bipolar transistor as an emitter follower instead of the FFT transistor Q2 operating as a source follower.
発明の詳細
な説明したように、本発明によれば、ソースフォロワま
たはエミッタフォロワを含む負帰還素子をもつフィード
バック回路により、フィートノくツク抵抗を下げても増
幅器自体の駆動能力を低下させないという効果が得られ
る。As described in detail, according to the present invention, a feedback circuit having a negative feedback element including a source follower or an emitter follower has the effect of not reducing the drive capability of the amplifier itself even if the foot knock resistance is lowered. can get.
第１図は本発明の一実施例を示す回路構成図、第２図は
従来技術の例を示す回路図である。
１１・・・１役場幅回路、１２・・・本発明のフィード
バック回路、２２・・・従来のフィードバック回路、Ｑ
ｌ−・・ゲート幅２００ｕａ （７）ＦＥＴ、 Ｑ２−
・・ゲート幅５０ｎｍのＦＥＴ、Ｑ３・・・ゲート幅５
０ｇｍのＦＥＴ、ＣＩ・＝ＳＰＦのキャパシタ、Ｒ１、
Ｒ２・・・バイアス用抵抗（４００Ω）、Ｒ３、Ｒ４・
・・フィードバック抵抗特許出願人 日本電気株式会
社
代 理 人 弁理士 熊谷雄太部FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIG. 2 is a circuit diagram showing an example of the prior art. 11... 1 office width circuit, 12... Feedback circuit of the present invention, 22... Conventional feedback circuit, Q
l-...Gate width 200ua (7) FET, Q2-
...FET with gate width 50 nm, Q3...gate width 5
0gm FET, CI・=SPF capacitor, R1,
R2...Bias resistance (400Ω), R3, R4.
...Feedback resistance patent applicant NEC Corporation Representative Patent attorney Yutabe Kumagai
Claims (2)
特徴とするフィードバック回路。(1) A feedback circuit characterized by having a negative feedback circuit including a source follower.
を特徴とするフィードバック回路。(2) A feedback circuit characterized by having a negative feedback circuit including an emitter follower.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31329390A JPH04183103A (en) | 1990-11-19 | 1990-11-19 | Feedback circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31329390A JPH04183103A (en) | 1990-11-19 | 1990-11-19 | Feedback circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH04183103A true JPH04183103A (en) | 1992-06-30 |
Family
ID=18039480
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP31329390A Pending JPH04183103A (en) | 1990-11-19 | 1990-11-19 | Feedback circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH04183103A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007013635A (en) * | 2005-06-30 | 2007-01-18 | Icom Inc | Variable gain amplifier and differential amplifier |
| JP2010193258A (en) * | 2009-02-19 | 2010-09-02 | Renesas Electronics Corp | Ask modulator |
| JP2015015643A (en) * | 2013-07-05 | 2015-01-22 | ローム株式会社 | Signal transmission circuit |
-
1990
- 1990-11-19 JP JP31329390A patent/JPH04183103A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007013635A (en) * | 2005-06-30 | 2007-01-18 | Icom Inc | Variable gain amplifier and differential amplifier |
| JP2010193258A (en) * | 2009-02-19 | 2010-09-02 | Renesas Electronics Corp | Ask modulator |
| JP2015015643A (en) * | 2013-07-05 | 2015-01-22 | ローム株式会社 | Signal transmission circuit |
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