JPH0618311B2 - Low frequency amplifier circuit - Google Patents
Low frequency amplifier circuitInfo
- Publication number
- JPH0618311B2 JPH0618311B2 JP60272699A JP27269985A JPH0618311B2 JP H0618311 B2 JPH0618311 B2 JP H0618311B2 JP 60272699 A JP60272699 A JP 60272699A JP 27269985 A JP27269985 A JP 27269985A JP H0618311 B2 JPH0618311 B2 JP H0618311B2
- Authority
- JP
- Japan
- Prior art keywords
- amplifier
- output
- input terminal
- inverting
- amplifier circuit
- 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
Landscapes
- Networks Using Active Elements (AREA)
- Amplifiers (AREA)
Description
【発明の詳細な説明】 （産業上の利用分野） 本発明は低周波増幅回路に関し、特に広帯域、低歪率の
差動出力を得ることのできる低周波増幅回路に関する。The present invention relates to a low frequency amplifier circuit, and more particularly to a low frequency amplifier circuit capable of obtaining a wide band and low distortion differential output.
（従来の技術） 従来、この種の低周波増幅回路としては、差動（平衡）
出力を得るために第２図のように同一利得の反転増幅器
９と非反転増幅器８とを組み合わせたものと、第３図の
ように出力が不平衡である増幅器10の出力端子に出力ト
ランス11を接続し、不平衡出力を平衡出力に変換するも
の等があった。(Prior Art) Conventionally, this type of low-frequency amplifier circuit has a differential (balanced)
In order to obtain an output, a combination of an inverting amplifier 9 and a non-inverting amplifier 8 having the same gain as shown in FIG. 2 and an output transformer 11 is connected to the output terminal of an amplifier 10 whose output is unbalanced as shown in FIG. There was a device for connecting an unbalanced output to a balanced output.
（発明が解決しようとする問題点） 低周波信号を伝送する際には、外来雑音の影響を少なく
するため、伝送線路として平衡線路を用いることが多
い。しかしながら、伝送線路が短い場合、あるいは伝送
線路の受端側に制約がある場合に伝送線路の片側を受端
側で接地することがある。ところが、第２図の増幅回路
の出力信号を片側接地の伝送線路に供給すると受端側に
伝送される信号の振幅が平衡線路の場合に比べて半分に
減少してしまう。(Problems to be Solved by the Invention) When transmitting a low-frequency signal, a balanced line is often used as a transmission line in order to reduce the influence of external noise. However, when the transmission line is short, or when the receiving end side of the transmission line is restricted, one side of the transmission line may be grounded at the receiving end side. However, when the output signal of the amplifier circuit of FIG. 2 is supplied to the transmission line grounded on one side, the amplitude of the signal transmitted to the receiving end side is reduced to half compared with the case of the balanced line.
一方、第３図の低周波増幅回路で片側接地の伝送線路に
信号を供給すれば受端側に伝送される信号の振幅は平衡
線路の場合と同じである。しかし、第３図の増幅回路の
伝送特性は、出力トランス11自体の伝送特性に大部分依
存してしまう。出力トランス11の振幅特性、歪等はトラ
ンスのコア材により決定される。このためかかる増幅回
路では使用周波数範囲や使用レベルに制限を受ける。On the other hand, if a signal is supplied to the transmission line grounded on one side in the low frequency amplifier circuit of FIG. 3, the amplitude of the signal transmitted to the receiving end side is the same as that of the balanced line. However, the transmission characteristic of the amplifier circuit of FIG. 3 largely depends on the transmission characteristic of the output transformer 11 itself. The amplitude characteristic, distortion, etc. of the output transformer 11 are determined by the core material of the transformer. Therefore, such an amplifier circuit is limited in the frequency range used and the level used.
そこで、本発明の目的は、出力端に接続される伝送線路
が平衡線路であるか不平衡線路であるかによって伝送さ
れる信号の振幅が影響されず、しかも広い周波数範囲に
わたって歪が少ない低周波増幅回路の提供にある。Therefore, an object of the present invention is to reduce the amplitude of a signal transmitted depending on whether a transmission line connected to an output end is a balanced line or an unbalanced line, and yet to have a low frequency with little distortion over a wide frequency range. In the provision of an amplifier circuit.
（問題点を解決するための手段） 前述の問題点を解決するために本発明が提供する低周波
増幅回路は、第１の反転入力端子及び第１の非反転入力
端子を有し利得がＧである第１の差動増幅器と、第２の
反転入力端子及び第２の非反転入力端子を有し利得がＧ
である第２の差動増幅器と、前記第１の差動増幅器の出
力信号を増幅し前記第２の非反転入力端子に加える非反
転増幅器と、前記第２の差動増幅器の出力信号を増幅し
前記第１の反転入力端子に加える反転増幅器とからな
り、前記非反転増幅器及び反転増幅器の利得はそれぞれ
1/G及び-1/Gであり、入力信号は前記第１の非反転入力
端子及び前記第２の反転入力端子に加えられ、前記第１
の差動増幅器の出力端子と前記第２の差動増幅器の出力
端子との間から出力信号を取り出すことを特徴とする。(Means for Solving Problems) A low-frequency amplifier circuit provided by the present invention to solve the above problems has a first inverting input terminal and a first non-inverting input terminal and has a gain of G And a second differential amplifier and a second non-inverting input terminal and a gain of G
A second differential amplifier, a non-inverting amplifier that amplifies the output signal of the first differential amplifier and applies it to the second non-inverting input terminal, and an output signal of the second differential amplifier. And an inverting amplifier applied to the first inverting input terminal, wherein the gains of the non-inverting amplifier and the inverting amplifier are respectively
1 / G and -1 / G, the input signal being applied to the first non-inverting input terminal and the second inverting input terminal,
The output signal is taken out between the output terminal of the differential amplifier and the output terminal of the second differential amplifier.
（実施例） 次に、本発明の低周波増幅回路について添附図面を参照
して詳細に説明する。(Embodiment) Next, a low frequency amplifier circuit of the present invention will be described in detail with reference to the accompanying drawings.
第１図は本発明の低周波増幅回路の一実施例を示すブロ
ック図である。入力端子１に供給された入力信号は第１
の差動増幅器２の非反転入力端子及び第２の差動増幅器
３の反転入力端子に供給され増幅される。第１の差動増
幅器２の出力信号100は出力端子６に出力されると共に
非反転増幅器４により増幅される。この増幅された出力
信号101は第２の差動増幅器３の非反転入力端子に供給
される。また、第２の差動増幅器３の出力信号102は出
力端子７に出力されると共に反転増幅器５により増幅さ
れる。この増幅された出力信号103は第１の差動増幅器
２の反転入力端子に供給される。FIG. 1 is a block diagram showing an embodiment of a low frequency amplifier circuit of the present invention. The input signal supplied to the input terminal 1 is the first
Is supplied to the non-inverting input terminal of the differential amplifier 2 and the inverting input terminal of the second differential amplifier 3 and is amplified. The output signal 100 of the first differential amplifier 2 is output to the output terminal 6 and is amplified by the non-inverting amplifier 4. The amplified output signal 101 is supplied to the non-inverting input terminal of the second differential amplifier 3. The output signal 102 of the second differential amplifier 3 is output to the output terminal 7 and is amplified by the inverting amplifier 5. The amplified output signal 103 is supplied to the inverting input terminal of the first differential amplifier 2.
ここで２つの差動増幅器２，３の利得をＧ、非反転増幅
器の利得をｇ、反転増幅器５の利得を−ｇとし、入力信
号の電圧をＶin、出力端子６，７の出力信号の電圧をそ
れぞれＶout１，Ｖout２とすると、差動出力電圧Ｖout
は次の式で表わすことができる。Here, the gain of the two differential amplifiers 2 and 3 is G, the gain of the non-inverting amplifier is g, the gain of the inverting amplifier 5 is −g, the voltage of the input signal is V in , and the output signals of the output terminals 6 and 7 are If the voltages are V out 1 and V out 2, respectively, the differential output voltage V out
Can be expressed by the following equation.
次に、出力端子の片側を接地した場合の出力信号
Ｖout′は、 Ｖout′＝ＧＶin（又は−ＧＶin）・・・・・・（２） （１），（２）式よりｇ＝1/Gにそれぞれの増幅器の利
得を設定すれば、 ｜Ｖout｜＝｜Ｖout′｜＝ＧＶinとなる。 Next, the output signal V out ′ when one side of the output terminal is grounded is V out ′ = GV in (or −GV in ) ... (2) From equations (1) and (2), g if = 1 / G setting the gain of each amplifier, | a = GV in | V out | = | V out '.
すなわち、本実施例の低周波増幅回路では、ｇ＝1/Gに
それぞれの増幅器の利得を設定することにより増幅回路
の出力を平衡あるいは不平衡のどちらで使用しても出力
レベルが変化しないようにすることができる。That is, in the low frequency amplifier circuit of the present embodiment, the output level of the amplifier circuit is set to g = 1 / G so that the output level does not change whether the output of the amplifier circuit is balanced or unbalanced. Can be
また、本実施例は、出力トランスを用いずに低周波増幅
回路を構成しているので、周波数帯域が広く、歪が少な
い。Further, in this embodiment, since the low frequency amplifier circuit is configured without using the output transformer, the frequency band is wide and the distortion is small.
（発明の効果） 以上説明したように本発明によれば、平衡伝送路又は不
平衡伝送路のいずれに出力を供給しても出力信号レベル
が変化せず、周波数帯域が広く、歪が少ない低周波増幅
回路を提供できる。As described above, according to the present invention, the output signal level does not change regardless of whether the output is supplied to the balanced transmission line or the unbalanced transmission line, the frequency band is wide, and the distortion is low. A frequency amplifier circuit can be provided.
第１図は本発明の低周波増幅回路の一実施例を示すブロ
ック図、第２図及び第３図は従来の低周波増幅回路のブ
ロック図である。 １……入力端子、２，３……差動増幅器、４，８……非
反転増幅器、５，９……反転増幅器、６，７……出力端
子、10……増幅器、11……出力トランス。FIG. 1 is a block diagram showing an embodiment of a low frequency amplifier circuit of the present invention, and FIGS. 2 and 3 are block diagrams of a conventional low frequency amplifier circuit. 1 ... input terminal, 2, 3 ... differential amplifier, 4, 8 ... non-inverting amplifier, 5, 9 ... inverting amplifier, 6, 7 ... output terminal, 10 ... amplifier, 11 ... output transformer .
Claims (1)
端子を有し利得がＧである第１の差動増幅器と、第２の
反転入力端子及び第２の非反転入力端子を有し利得がＧ
である第２の差動増幅器と、前記第１の差動増幅器の出
力信号を増幅し前記第２の非反転入力端子に加える非反
転増幅器と、前記第２の差動増幅器の出力信号を増幅し
前記第１の反転入力端子に加える反転増幅器とからな
り、前記非反転増幅器及び反転増幅器の利得はそれぞれ
１／Ｇ及び−１／Ｇであり、入力信号は前記第１の非反
転入力端子及び前記第２の反転入力端子に加えられ、前
記第１の差動増幅器の出力端子と前記第２の差動増幅器
の出力端子との間から出力信号を取り出すことを特徴と
する低周波増幅回路。1. A first differential amplifier having a first inverting input terminal and a first non-inverting input terminal having a gain of G, a second inverting input terminal and a second non-inverting input terminal. Owned gain is G
A second differential amplifier, a non-inverting amplifier that amplifies the output signal of the first differential amplifier and applies it to the second non-inverting input terminal, and an output signal of the second differential amplifier. An inverting amplifier applied to the first inverting input terminal, the gains of the non-inverting amplifier and the inverting amplifier are 1 / G and -1 / G, respectively, and the input signal is the first non-inverting input terminal and A low-frequency amplifier circuit, which is applied to the second inverting input terminal and extracts an output signal from between the output terminal of the first differential amplifier and the output terminal of the second differential amplifier.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60272699A JPH0618311B2 (en) | 1985-12-04 | 1985-12-04 | Low frequency amplifier circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60272699A JPH0618311B2 (en) | 1985-12-04 | 1985-12-04 | Low frequency amplifier circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS62132409A JPS62132409A (en) | 1987-06-15 |
| JPH0618311B2 true JPH0618311B2 (en) | 1994-03-09 |
Family
ID=17517557
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP60272699A Expired - Lifetime JPH0618311B2 (en) | 1985-12-04 | 1985-12-04 | Low frequency amplifier circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0618311B2 (en) |
-
1985
- 1985-12-04 JP JP60272699A patent/JPH0618311B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPS62132409A (en) | 1987-06-15 |
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