JPS6196822A - Signal switching circuit - Google Patents
Signal switching circuitInfo
- Publication number
- JPS6196822A JPS6196822A JP21763684A JP21763684A JPS6196822A JP S6196822 A JPS6196822 A JP S6196822A JP 21763684 A JP21763684 A JP 21763684A JP 21763684 A JP21763684 A JP 21763684A JP S6196822 A JPS6196822 A JP S6196822A
- Authority
- JP
- Japan
- Prior art keywords
- signal
- switching
- switching circuit
- differential amplifier
- current
- 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
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/16—Modifications for eliminating interference voltages or currents
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/51—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used
- H03K17/56—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices
- H03K17/60—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices the devices being bipolar transistors
- H03K17/603—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices the devices being bipolar transistors with coupled emitters
Landscapes
- Studio Circuits (AREA)
- Electronic Switches (AREA)
Abstract
Description
【発明の詳細な説明】
産業上の利用分野
この発明は映像信号の切替回路、とくに半導体集積回路
化に好適な映像信号切替回路に関する。DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a video signal switching circuit, and particularly to a video signal switching circuit suitable for semiconductor integrated circuit implementation.
従来例の構成とその問題点
映像信号の処理においては映像期間での映像信号の切替
時に、切替信号のリークによる画質の劣化を抑制するこ
とが要求される。ところで現在、一般的映像信号切替方
法としては映像信号を電流に変換し、切替信号に同期し
たトランジスタのオンオフ動作を用い切替を行っている
。Conventional configuration and its problems In video signal processing, it is required to suppress deterioration of image quality due to leakage of switching signals when switching video signals in a video period. By the way, currently, as a general video signal switching method, a video signal is converted into a current, and switching is performed using an on/off operation of a transistor in synchronization with a switching signal.
第１図は従来の映像信号切替回路を示す図であり、１，
２は差動増幅器を構成するｎｐｎ形トランジスタであり
、互いに工ばツタは共通接続され、さらに電流源３に接
続されている。トランジスタ１．２のコレクタには各々
４，５の負荷抵抗が接続されており、負荷抵抗４，６の
他端は電圧源６に接続されている。７は切替信号入力端
子、８は切替信号用切替直流電圧印加端子、９，１ｏは
各々切替出力端子である。FIG. 1 is a diagram showing a conventional video signal switching circuit.
Reference numeral 2 designates npn type transistors constituting a differential amplifier, which are commonly connected to each other and further connected to a current source 3. Load resistors 4 and 5 are connected to the collectors of the transistors 1 and 2, respectively, and the other ends of the load resistors 4 and 6 are connected to a voltage source 6. 7 is a switching signal input terminal, 8 is a switching signal switching DC voltage application terminal, and 9 and 1o are switching output terminals.
〜この信号切替回路は、第１図の破線で示したトランジ
スタ１のコレクタベース容量のため、第２図に示すＯＲ
の等何回路に置き換えられ、第２図のＣはトランジスタ
１のコレクタペース容量であり、Ｒはトランジスタ１の
コレクタに接続されて ゛いる負荷抵抗である。第
２図のＨの両端電圧をｖｏ。〜This signal switching circuit has an OR as shown in FIG. 2 due to the collector-base capacitance of transistor 1 shown by the broken line in FIG.
C in FIG. 2 is the collector space capacitance of transistor 1, and R is the load resistance connected to the collector of transistor 1. The voltage across H in FIG. 2 is vo.
信号電圧源をＥｉとす不と、入出力応答は次式に表この
ことから、第３図のａの切替信号を第１図の切替信号入
力端子７に入力し、トランジスタ′１゜２をオン・オフ
すると、出力端子９の出力信号は信号電流源３が無信号
状態の場合、式（１）に示すよう切替信号に対し微分特
性をもったリーク信号を含むｂの波形になる。Assuming that the signal voltage source is Ei, the input/output response is shown in the following equation.From this, the switching signal a in Fig. 3 is input to the switching signal input terminal 7 in Fig. 1, and the transistor '1゜2 is When turned on and off, when the signal current source 3 is in a no-signal state, the output signal of the output terminal 9 has a waveform b including a leak signal having differential characteristics with respect to the switching signal as shown in equation (1).
当然、このようなリーク信号が映像信号の映像期間に存
在すれば画質の劣化を招き、式（１）より切替信号の変
化、；レクタベース容量の変化、負荷抵抗値の変化の要
因でリーク信号が変化し画像の変化という不都合が生じ
る。Naturally, if such a leak signal exists during the video period of the video signal, it will cause deterioration of the image quality, and from equation (1), the leak signal will be reduced due to factors such as changes in the switching signal, changes in the reflector base capacitance, and changes in the load resistance value. changes, causing the inconvenience of a change in the image.
発明の目的
この発明は上記の従来例で生じた欠点を排除すべくなさ
れたものであり、画質の劣化を招く切替信号のリーク信
号を抑圧することができ、かつ半導体集積化に好適な信
号切替回路を提供するものである。Purpose of the Invention The present invention has been made in order to eliminate the drawbacks that occurred in the above-mentioned conventional example, and provides a signal switching method that can suppress leakage signals of switching signals that cause deterioration of image quality and is suitable for semiconductor integration. It provides a circuit.
発明の構成
本発明の構成は、信号の切替回路を形成する第１の差動
増幅器に対し、さらに別の信号切替用の第２の差動増幅
器を結合する。第１の差動増幅器に従来例同様に信号電
流及び直流電流を与え、第２の差動増幅器には無信号状
態にした直流電流のみを与える。このとき第１の差動増
幅器出力では切替信号とリーク信号、第２の差動増幅器
の出力ではリーク信号のみが得られ、これら切替信号と
リーク信号また同一極性のリーク信号を次段の差動増幅
器に入力することで次段の差動増幅器の出力は、リーク
信号が除去された切替信号のみを得ることができる。Configuration of the Invention In the configuration of the present invention, a second differential amplifier for signal switching is further coupled to a first differential amplifier forming a signal switching circuit. A signal current and a direct current are applied to the first differential amplifier as in the conventional example, and only a direct current in a no-signal state is applied to the second differential amplifier. At this time, the switching signal and the leak signal are obtained at the output of the first differential amplifier, and only the leak signal is obtained at the output of the second differential amplifier. By inputting the signal into the amplifier, only the switching signal from which the leakage signal has been removed can be obtained as the output of the next-stage differential amplifier.
実施例の説明
以下第４図に示す実施例回路を参照してこの発明を説明
する。この信号切替回路において、トランジスタＱ１．
Ｑ２は信号電流源工７．直流電流源工２を各々エバツタ
に接続された切替用差動増幅器を構成し、トランジスタ
Ｑ１．Ｑ２Ｏコレクタニは負荷抵抗Ｒ，，Ｒ２が各々接
続され、負荷抵抗Ｒ９゜Ｒ２の他端は直流電圧源Ｖｃｃ
に接続されている。トランジスタＱ３ 、Ｑ４は直流電
流源工、を各々の共通エミッタに接続された切替用差動
増幅器を構成し、トランジスタＱ３ 、Ｑ４のコレクタ
にハ負荷抵抗Ｒ３，Ｒ４が各々接続され、負荷抵抗Ｒ３
，Ｒ４の他端は直流電圧源Ｖｃｃ Ｋ接続されている。DESCRIPTION OF THE EMBODIMENTS The present invention will be described below with reference to the embodiment circuit shown in FIG. In this signal switching circuit, transistor Q1.
Q2 is the signal current source 7. Each DC current source 2 constitutes a switching differential amplifier connected to an evaporator, and transistors Q1 . The Q2O collector is connected to load resistors R, , R2, and the other end of the load resistor R9゜R2 is connected to the DC voltage source Vcc.
It is connected to the. Transistors Q3 and Q4 constitute a switching differential amplifier in which DC current sources are connected to their common emitters, and load resistors R3 and R4 are connected to the collectors of transistors Q3 and Q4, respectively.
, R4 is connected to a DC voltage source VccK.
またトランジスタＱ’＋Ｑ’のコレクタ出力は、次段の
電流源工。をもつトランジスタＱｓ 、Ｑｅで構成され
た差動増幅器に入力され、トランジスタＱ１（７）コレ
クタはトランジスタＱ５のベース、トランジスタＱ４の
コレクタはトランジスタＱａのベースに接続され、トラ
ンジスタＱ６のコレクタは負荷抵抗Ｒ６を通って接地さ
れ、トランジスタＱ６のコレクタは接地されている。Also, the collector output of transistor Q'+Q' is the current source of the next stage. The collector of transistor Q1 (7) is connected to the base of transistor Q5, the collector of transistor Q4 is connected to the base of transistor Qa, and the collector of transistor Q6 is connected to a load resistor R6. The collector of transistor Q6 is grounded.
端子１２は切替信号入力端子、端子１１は切替信号用基
準直流電圧印加端子、端子１３は出力端子である。また
、第５図は第４図の信号切替回路の各端子及び接続点の
波形であり、ａは切替ようとする信号電流波形であり、
ｂの切替信号を端子１２に入力したときのトランジスタ
Ｑ１のコレクタ、トランジスタＱ４のコレクタ出力波形
は各々ｃ、ｄとなり、端子１３の出力波形はｅの出力波
形となる。すなわち信号切替回路で発生する切替信号の
リーク信号のみを無信号入力の信号切替回路で発生し、
信号切替回路で得られた信号とリーク信号とを次段の差
動増幅器に入力し、同相除去の機能からリーク信号のみ
が除去されることになる。Terminal 12 is a switching signal input terminal, terminal 11 is a switching signal reference DC voltage application terminal, and terminal 13 is an output terminal. Moreover, FIG. 5 shows the waveforms of each terminal and connection point of the signal switching circuit of FIG. 4, and a is the signal current waveform to be switched,
When the switching signal b is input to the terminal 12, the output waveforms of the collector of the transistor Q1 and the collector of the transistor Q4 are c and d, respectively, and the output waveform of the terminal 13 is the output waveform of e. In other words, only the leak signal of the switching signal generated in the signal switching circuit is generated in the signal switching circuit with no signal input,
The signal obtained by the signal switching circuit and the leak signal are input to the next stage differential amplifier, and only the leak signal is removed by the common mode removal function.
この発明によれば切替信号の大きさによりリーク信号が
式（１）で示すように影響されることなく次段の差動増
幅器で除去可能となる。According to the present invention, the leakage signal can be removed by the next stage differential amplifier without being affected by the magnitude of the switching signal as shown in equation (1).
発明の効果
以上の説明から明らかなように、この発明の信号切替回
路においては、切替信号のリーク信号発生回路を設は映
像信号の切替時の切替信号のリーク信号を次段の差動増
幅器で同相除去して映像期間での影響をなくシ、従来例
で生じた不都合はことごとく排除される。またこの発明
は信号切替回路に同一特性をもつ差動増幅器を追加した
ものであるだめ、回路の半導体集積回路化に好適な信号
切替回路を得ることができる。Effects of the Invention As is clear from the above explanation, in the signal switching circuit of the present invention, a switching signal leakage signal generation circuit is provided to generate a leakage signal of the switching signal when switching the video signal by using the next stage differential amplifier. By removing the common phase and eliminating the influence on the video period, all the inconveniences that occurred in the conventional example are eliminated. Furthermore, since the present invention adds a differential amplifier having the same characteristics to the signal switching circuit, it is possible to obtain a signal switching circuit suitable for semiconductor integrated circuits.
第１図は従来例の信号切替回路図、第２図は切替信号回
路部の等価回路図、第３図は第２図示等価回路図の入出
力波形を示す図、第４図はこの発明の一実施例の信号切
替回路図、第５図は第４図の回路での実施例の信号波形
図である。
Ｑ１〜Ｑ６・・・・・・トランジスタ、Ｒ１−Ｒ６・・
・・・・抵抗、■、〜工、・・・・・・電流源、１１・
・・・・・信号切替用基準直流電圧印加端子、１２・・
・・・・切替信号入力端子、１３・・・・・・出力端子
。
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
（ｂ）ニー、−Fig. 1 is a signal switching circuit diagram of the conventional example, Fig. 2 is an equivalent circuit diagram of the switching signal circuit section, Fig. 3 is a diagram showing input/output waveforms of the equivalent circuit diagram shown in Fig. 2, and Fig. 4 is a diagram of the present invention. FIG. 5 is a signal switching circuit diagram of an embodiment. FIG. 5 is a signal waveform diagram of an embodiment of the circuit of FIG. Q1-Q6...Transistor, R1-R6...
...Resistance, ■, ...Current source, 11.
...Reference DC voltage application terminal for signal switching, 12...
...Switching signal input terminal, 13...Output terminal. Name of agent: Patent attorney Toshio Nakao and 1 other person 1st
Figure 2 Figure 3 (b) Knee, -
Claims (1)
回路でこの切替回路出力と直流電流のみの同一形式切替
回路での切替回路出力とをそれぞれ入力する差動増幅器
をそなえた信号切替回路。(1) A signal switching circuit equipped with a differential amplifier that inputs the switching circuit output of a signal current that is a combination of signal current and DC current, and the switching circuit output of a switching circuit of the same type that only uses DC current. .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP21763684A JPS6196822A (en) | 1984-10-17 | 1984-10-17 | Signal switching circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP21763684A JPS6196822A (en) | 1984-10-17 | 1984-10-17 | Signal switching circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS6196822A true JPS6196822A (en) | 1986-05-15 |
Family
ID=16707368
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP21763684A Pending JPS6196822A (en) | 1984-10-17 | 1984-10-17 | Signal switching circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6196822A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5115151A (en) * | 1990-06-08 | 1992-05-19 | Western Digital Corporation | Triple comparator circuit |
-
1984
- 1984-10-17 JP JP21763684A patent/JPS6196822A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5115151A (en) * | 1990-06-08 | 1992-05-19 | Western Digital Corporation | Triple comparator circuit |
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