JP4817126B2 - Variable damping device - Google Patents

Variable damping device Download PDF

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JP4817126B2
JP4817126B2 JP2007114927A JP2007114927A JP4817126B2 JP 4817126 B2 JP4817126 B2 JP 4817126B2 JP 2007114927 A JP2007114927 A JP 2007114927A JP 2007114927 A JP2007114927 A JP 2007114927A JP 4817126 B2 JP4817126 B2 JP 4817126B2
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attenuator
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JP2008271451A (en
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悟 鈴木
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Yokogawa Electric Corp
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Description

本発明は、例えば、オシロスコープ、電力計等の測定器の入力部や、ファンクションジェネレータ等の信号発生器の出力部等に用いられ、本装置の入力端子に入力された電気信号を減衰して出力端子から出力する可変減衰装置に関し、詳しくは、大きな減衰量であってもノイズの影響等を少なくし、広帯域にわたって入力信号の波形の劣化を抑えた可変減衰装置に関するものである。   The present invention is used, for example, in an input unit of a measuring instrument such as an oscilloscope or a wattmeter, or an output unit of a signal generator such as a function generator, and attenuates and outputs an electric signal input to an input terminal of the apparatus. More particularly, the present invention relates to a variable attenuating device that reduces the influence of noise and the like and suppresses the deterioration of the waveform of an input signal over a wide band even when the amount of attenuation is large.

測定器の入力部や信号発生器の出力部等では、測定対象からの信号や測定対象への信号を適切な信号レベルにするため可変減衰装置が設けられる（例えば、特許文献１参照）。   A variable attenuator is provided in the input unit of the measuring instrument, the output unit of the signal generator, and the like in order to set the signal from the measuring object and the signal to the measuring object to an appropriate signal level (see, for example, Patent Document 1).

図５、図６は、従来の可変減衰装置の構成例を示した図であり、可変減衰装置の入力側からみた入力インピーダンスを１［ＭΩ］にした例である。また、同一のもには同一符号を付してある。   5 and 6 are diagrams showing a configuration example of a conventional variable attenuating device, in which the input impedance viewed from the input side of the variable attenuating device is 1 [MΩ]. Moreover, the same code | symbol is attached | subjected to the same thing.

図５は、減衰比１／１００の１個の減衰器によって、入力信号の減衰量を１／１、１／１００に可変できる装置例である。図６は、減衰比１／１０の減衰器を２段直列に並べ、減衰量を１／１、１／１０、１／１００に可変できる装置例である。   FIG. 5 shows an example of an apparatus in which the attenuation amount of an input signal can be varied between 1/1 and 1/100 with one attenuator having an attenuation ratio of 1/100. FIG. 6 shows an example of an apparatus in which two stages of attenuators with an attenuation ratio of 1/10 are arranged in series and the attenuation can be varied to 1/1, 1/10, and 1/100.

図５において、入力端子Ｐｉは本装置の入力端子であり、出力端子Ｐｏは本装置の出力端子であり、入力端子Ｐｉに入力された入力信号（電気信号）を所望の減衰量（１／１〜１／１００）で減衰させて出力端子Ｐｏから出力する。   In FIG. 5, an input terminal Pi is an input terminal of the apparatus, an output terminal Po is an output terminal of the apparatus, and an input signal (electric signal) input to the input terminal Pi is converted into a desired attenuation amount (1/1). ˜ 1/100) and output from the output terminal Po.

信号線Ｌ１と信号線Ｌ２は入力端子Ｐｉ、出力端子Ｐｏ間に並列に設けられる。信号線Ｌ１は減衰器がなく（減衰比１／１）、信号線Ｌ２上に減衰器１（減衰比１／１００）が設けられる。   The signal line L1 and the signal line L2 are provided in parallel between the input terminal Pi and the output terminal Po. The signal line L1 has no attenuator (attenuation ratio 1/1), and the attenuator 1 (attenuation ratio 1/100) is provided on the signal line L2.

切替スイッチは、入力側スイッチＳＷ１ａ、出力側スイッチＳＷ１ｂから構成され、スイッチＳＷ１ａ、ＳＷ１ｂは連動して切替を行なう。すなわち、切替スイッチＳＷ１ａ、ＳＷ１ｂは、信号線Ｌ１または信号線Ｌ２を択一的に選択し、選択した信号線Ｌ１、Ｌ２を介して入力端子Ｐｉからの電気信号を出力端子Ｐｏに伝送させる。   The changeover switch includes an input side switch SW1a and an output side switch SW1b, and the switches SW1a and SW1b are switched in conjunction with each other. That is, the selector switches SW1a and SW1b selectively select the signal line L1 or the signal line L2, and transmit the electrical signal from the input terminal Pi to the output terminal Po via the selected signal lines L1 and L2.

抵抗（抵抗値１［ＭΩ］）Ｒ０は、出力側スイッチＳＷ１ｂの出力端と出力端子Ｐｏ間に設けられ、一端が出力端子Ｐｏに電気的に接続され、他端がグランドに接地される。   The resistor (resistance value 1 [MΩ]) R0 is provided between the output terminal of the output side switch SW1b and the output terminal Po, one end is electrically connected to the output terminal Po, and the other end is grounded.

減衰器１は、抵抗Ｒ１ａと抵抗Ｒ１ｂとで分圧回路を構成し、抵抗Ｒ１ａ、Ｒ１ｂの接点が減衰器１の出力になる。抵抗Ｒ１ａ、Ｒ１ｂの抵抗値それぞれは、例えば、９９０［ｋΩ］、１０．１［ｋΩ］である。   In the attenuator 1, a resistor R1a and a resistor R1b constitute a voltage dividing circuit, and a contact point between the resistors R1a and R1b becomes an output of the attenuator 1. The resistance values of the resistors R1a and R1b are, for example, 990 [kΩ] and 10.1 [kΩ].

このような装置の動作を説明する。
減衰量を１／１とする場合、切替スイッチＳＷ１ａ、ＳＷ１ｂが、接続を切り替えて信号線Ｌ１を選択し、信号線Ｌ１を端子Ｐｉ，Ｐｏに接続させる。これによって、選択された信号線Ｌ１を介して入力端子Ｐｉからの電気信号が、減衰量１／１で出力端子Ｐｏに伝送される。 The operation of such an apparatus will be described.
When the attenuation is 1/1, the changeover switches SW1a and SW1b switch the connection, select the signal line L1, and connect the signal line L1 to the terminals Pi and Po. As a result, the electrical signal from the input terminal Pi is transmitted to the output terminal Po with the attenuation of 1/1 via the selected signal line L1.

減衰量を１／１００とする場合、切替スイッチＳＷ１ａ、ＳＷ１ｂが、接続を切り替えて減衰器１を有する信号線Ｌ２を選択し、信号線Ｌ２を端子Ｐｉ，Ｐｏに接続させる。これによって、入力端子Ｐｉからの信号が、スイッチＳＷ１ａを介して信号線Ｌ２上の減衰器１に入力される。そして、減衰器１が、信号レベルを１／１００に減衰しスイッチＳＷ１ｂを介して出力端子Ｐｉに出力する。   When the attenuation is set to 1/100, the change-over switches SW1a and SW1b select the signal line L2 having the attenuator 1 by switching the connection, and connect the signal line L2 to the terminals Pi and Po. As a result, the signal from the input terminal Pi is input to the attenuator 1 on the signal line L2 via the switch SW1a. Then, the attenuator 1 attenuates the signal level to 1/100 and outputs it to the output terminal Pi via the switch SW1b.

続いて、図６において、入力端子Ｐｉと出力端子Ｐｏ間に、入力端子Ｐｉ側から順にスイッチＳＷ２ａ、並列に設けられた信号線Ｌ３、Ｌ４、スイッチＳＷ２ｂ、スイッチＳＷ３ａ、並列に設けられた信号線Ｌ５，Ｌ６、スイッチＳＷ３ｂ、抵抗Ｒ０が設けられる。   Subsequently, in FIG. 6, between the input terminal Pi and the output terminal Po, the switch SW2a, the signal lines L3 and L4 provided in parallel, the switch SW2b, the switch SW3a, and the signal lines provided in parallel from the input terminal Pi side. L5 and L6, a switch SW3b, and a resistor R0 are provided.

信号線Ｌ３，Ｌ５は減衰器が無く、減衰比１／１である。信号線Ｌ４には減衰器２が設けられ、信号線Ｌ６には減衰器３が設けられ、減衰器２、３共に減衰比１／１０である。   The signal lines L3 and L5 have no attenuator and have an attenuation ratio of 1/1. The signal line L4 is provided with an attenuator 2, the signal line L6 is provided with an attenuator 3, and both the attenuators 2 and 3 have an attenuation ratio of 1/10.

減衰器２は、抵抗による分圧回路であり、抵抗Ｒ２ａ、Ｒ２ｂを有する。減衰器３も、抵抗による分圧回路であり、抵抗Ｒ３ａ，Ｒ３ｂを有する。   The attenuator 2 is a voltage dividing circuit using resistors, and includes resistors R2a and R2b. The attenuator 3 is also a voltage dividing circuit using resistors, and includes resistors R3a and R3b.

切替スイッチＳＷ２ａ、ＳＷ２ｂは、連動して切替を行ない、信号線Ｌ３または信号線Ｌ４を択一的に選択し、選択した信号線Ｌ３、Ｌ４を介して入力端子Ｐｉからの電気信号を後段の切替スイッチ回路ＳＷ３ａに出力する。   The change-over switches SW2a and SW2b are switched in conjunction to selectively select the signal line L3 or the signal line L4, and switch the electrical signal from the input terminal Pi through the selected signal lines L3 and L4 to the subsequent stage. Output to the switch circuit SW3a.

切替スイッチＳＷ３ａ、ＳＷ３ｂは、連動して切替を行ない、信号線Ｌ５または信号線Ｌ６を択一的に選択し、選択した信号線Ｌ５、Ｌ６を介して切替スイッチＳＷ２ｂからの電気信号を出力端子Ｐｏに出力する。   The change-over switches SW3a and SW3b are switched in conjunction to selectively select the signal line L5 or the signal line L6, and the electric signal from the change-over switch SW2b is output to the output terminal Po via the selected signal lines L5 and L6. Output to.

このような装置の動作を説明する。
減衰量を１／１とする場合、切替スイッチＳＷ２ａ、ＳＷ２ｂが、接続を切り替えて信号線Ｌ３を選択し、切替スイッチＳＷ３ａ、ＳＷ３ｂが、接続を切り替えて信号線Ｌ５を選択する。これにより、入力端子Ｐｉ、信号線Ｌ３，Ｌ５，出力端子Ｐｏが電気的に接続され、入力端子Ｐｉからの電気信号が、減衰量１／１で出力端子Ｐｏに伝送される。 The operation of such an apparatus will be described.
When the attenuation amount is 1/1, the changeover switches SW2a and SW2b switch the connection and select the signal line L3, and the changeover switches SW3a and SW3b switch the connection and select the signal line L5. As a result, the input terminal Pi, the signal lines L3 and L5, and the output terminal Po are electrically connected, and the electrical signal from the input terminal Pi is transmitted to the output terminal Po with an attenuation of 1/1.

減衰量を１／１０とする場合、切替スイッチＳＷ２ａ、ＳＷ２ｂが、接続を切り替えて信号線Ｌ４（減衰器有りの経路）を選択し、切替スイッチＳＷ３ａ、ＳＷ３ｂが、接続を切り替えて信号線Ｌ５（減衰器無しの経路）を選択する。これにより、入力端子Ｐｉ、信号線Ｌ４，Ｌ５，出力端子Ｐｏが電気的に接続される。そして、入力端子Ｐｉからの電気信号の信号レベルが、減衰器２によって１／１０に減衰されて出力端子Ｐｏに伝送される。   When the attenuation is 1/10, the changeover switches SW2a and SW2b change the connection to select the signal line L4 (path with the attenuator), and the changeover switches SW3a and SW3b change the connection to change the signal line L5 ( Select a path without an attenuator. As a result, the input terminal Pi, the signal lines L4 and L5, and the output terminal Po are electrically connected. The signal level of the electrical signal from the input terminal Pi is attenuated to 1/10 by the attenuator 2 and transmitted to the output terminal Po.

減衰量を１／１００とする場合、切替スイッチＳＷ２ａ、ＳＷ２ｂが、接続を切り替えて信号線Ｌ４を選択し、切替スイッチＳＷ３ａ、ＳＷ３ｂが、接続を切り替えて信号線Ｌ６を選択する。これにより、入力端子Ｐｉ、信号線Ｌ４，Ｌ６，出力端子Ｐｏが電気的に接続される。そして、入力端子Ｐｉからの電気信号の信号レベルが、減衰器２、３それぞれによって１／１０づつ減衰され、全体として入力信号に対して１／１００に減衰されて出力端子Ｐｏに伝送される。   When the attenuation is set to 1/100, the changeover switches SW2a and SW2b switch the connection and select the signal line L4, and the changeover switches SW3a and SW3b switch the connection and select the signal line L6. Thereby, the input terminal Pi, the signal lines L4 and L6, and the output terminal Po are electrically connected. Then, the signal level of the electric signal from the input terminal Pi is attenuated by 1/10 by the attenuators 2 and 3 respectively, attenuated to 1/100 of the input signal as a whole, and transmitted to the output terminal Po.

特開２００１−３４５６５９号公報JP 2001-345659 A

このように減衰器有りの信号線、減衰器無しの信号線の経路を設け、これらの経路を選択することによって、所望の減衰量で入力信号を減衰して出力する。   In this way, the path of the signal line with the attenuator and the path of the signal line without the attenuator are provided, and by selecting these paths, the input signal is attenuated and output by a desired attenuation amount.

一般的に可変減衰装置は、どのような周波数帯域であっても、入力信号の波形の形状を劣化させることなく波形品位を保ったまま入力信号を減衰させることが要求される。また、可変減衰装置に接続される回路や機器に影響を与えないように、入力インピーダンスも一定である必要がある。   In general, the variable attenuator is required to attenuate the input signal while maintaining the waveform quality without degrading the shape of the waveform of the input signal in any frequency band. Also, the input impedance needs to be constant so as not to affect the circuits and devices connected to the variable attenuation device.

しかしながら、図５に示す装置（１段の減衰器１で１／１００に減衰）の場合、減衰器１の分圧比（抵抗Ｒ１ａの抵抗値＞＞抵抗Ｒ１ｂの抵抗値）が大きい。そのため、抵抗Ｒ１ａの寄生容量よって、数十［ＭＨｚ］を超えるような高周波数領域では、出力端子Ｐｏの信号にオーバーシュート等の現象が発生し、波形が歪んでしまい、波形品位が悪くなるという問題があった。   However, in the case of the apparatus shown in FIG. 5 (attenuated to 1/100 with the one-stage attenuator 1), the voltage dividing ratio of the attenuator 1 (resistance value of the resistor R1a >> resistance value of the resistor R1b) is large. Therefore, due to the parasitic capacitance of the resistor R1a, in a high frequency region exceeding several tens [MHz], a phenomenon such as overshoot occurs in the signal of the output terminal Po, the waveform is distorted, and the waveform quality is deteriorated. There was a problem.

また、抵抗Ｒ１ａの寄生容量の影響を補償するために抵抗Ｒ１ｂに並列に可変コンデンサを設けたとしても、抵抗Ｒ１ａ、Ｒ１ｂの抵抗比（約１００倍）が大きいため、寄生容量の容量変動に対し約１００倍の感度で補償用コンデンサを調整する必要があり、事実上、寄生容量の影響を除去することが非常に困難であるという問題があった。   Even if a variable capacitor is provided in parallel with the resistor R1b in order to compensate for the effect of the parasitic capacitance of the resistor R1a, the resistance ratio (about 100 times) of the resistors R1a and R1b is large. There is a problem that it is necessary to adjust the compensation capacitor with a sensitivity of about 100 times, and it is practically difficult to remove the influence of the parasitic capacitance.

一方、図６に示す装置（減衰比が１／１０の減衰器２、３を２段直列接続）の場合、減衰器２、３での分圧比が小さいので高周波数領域まで特性がよい。   On the other hand, in the case of the apparatus shown in FIG. 6 (attenuators 2 and 3 having an attenuation ratio of 1/10 are connected in two stages in series), the voltage dividing ratio at the attenuators 2 and 3 is small, so the characteristics are good up to the high frequency region.

しかしながら、どの減衰量であっても入力インピーダンスを１［ＭΩ］とする必要があるため、必然的に、抵抗Ｒ０と並列接続になる抵抗Ｒ２ｂ，Ｒ３ｂの抵抗値が大きくなる。これによって、出力側（出力端子Ｐｏ）からみた出力インピーダンスが大きくなり（図６では、約１００［ｋΩ］）、特に、減衰量１／１００の場合、抵抗Ｒ３ｂによる熱雑音が大きくなり、その結果、ノイズが大きくなるという問題があった。また、外部からの外来ノイズの影響も受けやすくなるという問題があった。   However, since it is necessary to set the input impedance to 1 [MΩ] regardless of the amount of attenuation, the resistance values of the resistors R2b and R3b connected in parallel with the resistor R0 are inevitably increased. As a result, the output impedance viewed from the output side (output terminal Po) is increased (in FIG. 6, about 100 [kΩ]). In particular, when the attenuation is 1/100, the thermal noise due to the resistor R3b increases. There was a problem that noise increased. In addition, there is a problem that it is easily affected by external noise from the outside.

そこで本発明の目的は、大きな減衰量であってもノイズの影響等を少なくし、広帯域にわたって入力信号の波形の劣化を抑えた可変減衰装置を実現することにある。   Accordingly, an object of the present invention is to realize a variable attenuation device that reduces the influence of noise and the like even with a large attenuation amount and suppresses the deterioration of the waveform of an input signal over a wide band.

請求項１記載の発明は、
入力端子に入力された電気信号を減衰して出力端子から出力する可変減衰装置において、
前記入力端子からの電気信号を、第１の抵抗と第２の抵抗の抵抗比で分圧して減衰させる初段の減衰器と、
前記初段の減衰器からの電気信号を、第３の抵抗と第４の抵抗の抵抗比で分圧して減衰させて前記出力端子に出力する後段の減衰器と、
前記後段の減衰器に並列に設けられ、第５の抵抗を介して接地されている信号線と、
前記後段の減衰器または前記信号線の一方を選択し、選択した後段の減衰器または信号線を介して、前記初段の減衰器からの出力を前記出力端子に伝送させる一対の切替スイッチと、
前記出力端子とグランドとの間に設けられる第６の抵抗とを設け、
前記初段の減衰器は、前記第１の抵抗が本減衰器の入力側と出力側との間に、前記第２の抵抗が本減衰器の出力側とグランドとの間に設けられ、
前記後段の減衰器は、前記第３の抵抗が本減衰器の入力側と出力側との間に、前記第４の抵抗が本減衰器の出力側とグランドとの間に設けられることを特徴とするものである。
請求項２記載の発明は、
入力端子に入力された電気信号を減衰して出力端子から出力する可変減衰装置において、
第１の経路と、
前記第１の経路と並列に設けられ、前記電気信号を抵抗で分圧して減衰させる減衰器を複数有する第２の経路と、
前記第１の経路または第２の経路の一方を選択し、選択した経路を介して前記入力端子からの電気信号を前記出力端子に伝送させる一対の第１の切替スイッチと、
前記出力端子とグランドとの間に設けられる第６の抵抗とを設け、
前記第２の経路は、
前記入力端子からの電気信号を、第１の抵抗と第２の抵抗の抵抗比で分圧して減衰させる初段の減衰器と、
前記初段の減衰器からの電気信号を、第３の抵抗と第４の抵抗の抵抗比で分圧して減衰させて前記出力端子に出力する後段の減衰器と、
前記後段の減衰器に並列に設けられ、第５の抵抗を介して接地されている信号線と、
前記後段の減衰器または前記信号線の一方を選択し、選択した後段の減衰器または信号線を介して、前記初段の減衰器からの出力を出力側の前記第１の切替スイッチに伝送させる一対の第２の切替スイッチとを備え、
前記初段の減衰器は、前記第１の抵抗が本減衰器の入力側と出力側との間に、前記第２の抵抗が本減衰器の出力側とグランドとの間に設けられ、
前記後段の減衰器は、前記第３の抵抗が本減衰器の入力側と出力側との間に、前記第４の抵抗が本減衰器の出力側とグランドとの間に設けられることを特徴とするものである。
請求項３記載の発明は、請求項２記載の発明において、
一端が前記入力端子に接続され、他端が入力側の前記第１の切替スイッチに接続される分圧用の第７の抵抗を設けたことを特徴とするものである。
請求項４記載の発明は、請求項１〜３のいずれかに記載の発明において、
入力インピーダンスが減衰量によらず一定となることを特徴とするものである。
The invention described in claim 1
In the variable attenuation device that attenuates the electrical signal input to the input terminal and outputs it from the output terminal,
A first-stage attenuator that divides and attenuates the electrical signal from the input terminal by a resistance ratio of the first resistor and the second resistor;
A subsequent- stage attenuator that divides and attenuates the electrical signal from the first-stage attenuator by a resistance ratio of a third resistor and a fourth resistor and outputs the divided signal to the output terminal;
Provided in parallel to the latter stage of the attenuator, a signal line is grounded via a fifth resistor,
A pair of changeover switches for selecting one of the subsequent attenuator or the signal line and transmitting the output from the first attenuator to the output terminal via the selected subsequent attenuator or signal line;
A sixth resistor provided between the output terminal and the ground;
In the first-stage attenuator, the first resistor is provided between the input side and the output side of the attenuator, and the second resistor is provided between the output side of the attenuator and the ground.
In the attenuator at the rear stage, the third resistor is provided between the input side and the output side of the attenuator, and the fourth resistor is provided between the output side of the attenuator and the ground. It is what.
The invention according to claim 2
In the variable attenuation device that attenuates the electrical signal input to the input terminal and outputs it from the output terminal,
A first path;
A second path provided in parallel with the first path, and having a plurality of attenuators that divide and attenuate the electrical signal by a resistor;
A pair of first changeover switches for selecting one of the first path or the second path and transmitting an electrical signal from the input terminal to the output terminal via the selected path;
A sixth resistor provided between the output terminal and the ground;
The second route is:
A first-stage attenuator that divides and attenuates the electrical signal from the input terminal by a resistance ratio of the first resistor and the second resistor;
A subsequent- stage attenuator that divides and attenuates the electrical signal from the first-stage attenuator by a resistance ratio of a third resistor and a fourth resistor and outputs the divided signal to the output terminal;
Provided in parallel to the latter stage of the attenuator, a signal line is grounded via a fifth resistor,
A pair that selects one of the latter-stage attenuator or the signal line and transmits the output from the first-stage attenuator to the first change-over switch on the output side via the selected latter-stage attenuator or signal line. A second changeover switch,
In the first-stage attenuator , the first resistor is provided between the input side and the output side of the attenuator, and the second resistor is provided between the output side of the attenuator and the ground.
In the attenuator at the rear stage, the third resistor is provided between the input side and the output side of the attenuator, and the fourth resistor is provided between the output side of the attenuator and the ground. It is what.
The invention according to claim 3 is the invention according to claim 2,
A seventh resistor for voltage division is provided, one end of which is connected to the input terminal and the other end is connected to the first changeover switch on the input side.
The invention according to claim 4 is the invention according to any one of claims 1 to 3,
The input impedance is constant regardless of the amount of attenuation.

抵抗で分圧して電気信号を減衰させる減衰器を２段配置し、後段の減衰器に対するスルー用の信号線（減衰比１／１）を抵抗を介して接地させるので、後段の減衰器中の抵抗の抵抗値を小さくできる。これにより、大きな減衰量（初段、後段両方の減衰器で減衰させる場合）であっても出力インピーダンスを小さくできると共に、２段の減衰器で入力信号を減衰するので各減衰器の分圧比を小さくでき、高周波数領域でも信号の波形品位が悪化しない。従って、大きな減衰量であってもノイズの影響等を少なくし、広帯域にわたって入力信号の波形の劣化を抑えることができる。   Two stages of attenuators that divide the voltage by resistors and attenuate the electrical signal are arranged, and the signal line for through (attenuation ratio 1/1) to the attenuators in the subsequent stage is grounded through the resistors. The resistance value of the resistor can be reduced. As a result, the output impedance can be reduced even with a large amount of attenuation (when attenuated by both the first-stage and subsequent-stage attenuators), and the input signal is attenuated by the two-stage attenuator, so the voltage dividing ratio of each attenuator is reduced. The waveform quality of the signal does not deteriorate even in the high frequency range. Therefore, even if the amount of attenuation is large, the influence of noise and the like can be reduced, and deterioration of the waveform of the input signal can be suppressed over a wide band.

以下図面を用いて本発明の実施の形態を説明する。
［第１の実施例］
図１〜図３は、本発明の第１の実施例を示した構成図であり、可変減衰装置の入力側からみた入力インピーダンスを１［ＭΩ］にした例を示している。ここで、図１は、入力信号に対する出力信号の減衰量を１／１とし、図２は減衰量を１／１０とし、図３は減衰量を１／１００とする構成例である。 Embodiments of the present invention will be described below with reference to the drawings.
[First embodiment]
1 to 3 are block diagrams showing a first embodiment of the present invention, showing an example in which the input impedance viewed from the input side of the variable attenuator is 1 [MΩ]. Here, FIG. 1 is an example of a configuration in which the attenuation amount of the output signal with respect to the input signal is 1/1, FIG. 2 is 1/10 attenuation amount, and FIG. 3 is 1/100 attenuation amount.

図１〜図３において、入力端子Ｐｉは本装置の入力端子であり、出力端子Ｐｏは本装置の出力端子であり、入力端子Ｐｉに入力された入力信号（電気信号）を所望の減衰量（１／１〜１／１００）で減衰させて出力端子Ｐｏから出力する。また、出力端子Ｐｏからの信号は、後段の高入力インピーダンスのバッファ回路（図示せず）に入力される。   1 to 3, an input terminal Pi is an input terminal of the present apparatus, an output terminal Po is an output terminal of the present apparatus, and an input signal (electric signal) input to the input terminal Pi is converted into a desired attenuation amount ( Attenuated by 1/1 to 1/100) and output from the output terminal Po. The signal from the output terminal Po is input to a subsequent high input impedance buffer circuit (not shown).

減衰器無しの信号線Ｌ７は、端子Ｐｉ，Ｐｏ間に設けられ、減衰比１／１であり、スルー用の経路である。   The signal line L7 without an attenuator is provided between the terminals Pi and Po, has an attenuation ratio of 1/1, and is a through path.

信号線Ｌ８は、信号線Ｌ７と並列に設けられ、抵抗で分圧する減衰器４、５を合計２個有する。   The signal line L8 is provided in parallel with the signal line L7, and has a total of two attenuators 4 and 5 that divide the voltage with resistors.

なお、信号線Ｌ７は、特許請求の範囲の第１の経路に相当し、信号線Ｌ８は第２の経路に相当する。

The signal line L7 corresponds to the first path in the claims, and the signal line L8 corresponds to the second path .

第１の切替スイッチＳＷ５ａ（入力側）、ＳＷ５ｂ（出力側）は、連動して切替を行ない、信号線Ｌ７または信号線Ｌ８を択一的に選択し、選択した信号線Ｌ７，Ｌ８を介して入力端子Ｐｉからの電気信号を出力端子Ｐｏに伝送させる。   The first change-over switches SW5a (input side) and SW5b (output side) are switched in conjunction to selectively select the signal line L7 or the signal line L8, and pass through the selected signal lines L7 and L8. An electric signal from the input terminal Pi is transmitted to the output terminal Po.

より詳細には、入力側のスイッチＳＷ５ａの入力端が入力端子Ｐｉに接続され、一方の出力端が信号線Ｌ７の一端に接続され、他方の出力端が信号線Ｌ８の一端に接続される。出力側のスイッチＳＷ５ｂの一方の入力端が信号線Ｌ７の他端に接続され、他方の入力端が信号線Ｌ８の他端に接続され、出力端が出力端子Ｐｏに接続される。   More specifically, the input end of the switch SW5a on the input side is connected to the input terminal Pi, one output end is connected to one end of the signal line L7, and the other output end is connected to one end of the signal line L8. One input end of the output-side switch SW5b is connected to the other end of the signal line L7, the other input end is connected to the other end of the signal line L8, and an output end is connected to the output terminal Po.

信号線Ｌ８は、初段の減衰器４、信号線Ｌ９に設けられる後段の減衰器５、減衰器無しの信号線Ｌ１０、第２の切替スイッチＳＷ６ａ（入力側）、ＳＷ６ｂ（出力側）を有し、切替スイッチＳＷ５ａからの入力信号の信号レベル（電圧の振幅）を、１／１０または１／１００に減衰してスイッチＳＷ５ｂに伝送する。ここで、初段とは、後段よりも入力端子Ｐｉに近く信号が先に入力されることを意味する。   The signal line L8 includes a first-stage attenuator 4, a subsequent-stage attenuator 5 provided on the signal line L9, a signal line L10 without an attenuator, a second changeover switch SW6a (input side), and SW6b (output side). The signal level (voltage amplitude) of the input signal from the changeover switch SW5a is attenuated to 1/10 or 1/100 and transmitted to the switch SW5b. Here, the first stage means that the signal is input earlier than the latter stage, closer to the input terminal Pi.

初段の減衰器４は、抵抗Ｒ４ａ（以下第１の抵抗ともいう）と抵抗Ｒ４ｂ（以下第２の抵抗ともいう）の抵抗比で信号を分圧する分圧回路であり、抵抗Ｒ４ａとＲ４ｂの接続点が減衰器４の出力になる。抵抗Ｒ４ａ、Ｒ４ｂの抵抗値それぞれは、例えば、９９０［ｋΩ］、２２２［ｋΩ］である。そして、減衰器４は、信号線Ｌ８の一端から入力された信号を、抵抗Ｒ４ａ、Ｒ４ｂの抵抗比に従って分圧して減衰し、スイッチＳＷ６ａに伝送する。なお、抵抗Ｒ４ａは信号線Ｌ８上に設けられ、抵抗Ｒ４ｂは信号線Ｌ８とグランド間に設けられる。 The first-stage attenuator 4 is a voltage dividing circuit that divides a signal by a resistance ratio of a resistor R4a (hereinafter also referred to as a first resistor) and a resistor R4b (hereinafter also referred to as a second resistor) , and the connection between the resistors R4a and R4b. The point becomes the output of the attenuator 4. The resistance values of the resistors R4a and R4b are, for example, 990 [kΩ] and 222 [kΩ]. The attenuator 4 divides and attenuates the signal input from one end of the signal line L8 according to the resistance ratio of the resistors R4a and R4b, and transmits the attenuated signal to the switch SW6a. The resistor R4a is provided on the signal line L8, and the resistor R4b is provided between the signal line L8 and the ground.

後段の減衰器５は、抵抗Ｒ５ａ（以下第３の抵抗ともいう）と抵抗Ｒ５ｂ（以下第４の抵抗ともいう）の抵抗比で信号を分圧する分圧回路であり、抵抗Ｒ５ａとＲ５ｂの接続点が減衰器５の出力になる。抵抗Ｒ５ａ、Ｒ５ｂの抵抗値それぞれは、例えば、２００［ｋΩ］、２２．７［ｋΩ］である。そして、減衰器５は、切替スイッチＳＷ６ａ、ＳＷ６ｂ間に設けられ、スイッチＳＷ６ａからの信号を、抵抗Ｒ５ａ、Ｒ５ｂの抵抗比に従って分圧して減衰し、スイッチＳＷ６ｂに伝送する。なお、抵抗Ｒ５ａは信号線Ｌ９上に設けられ、抵抗Ｒ５ｂは信号線Ｌ９とグランド間に設けられる。 The attenuator 5 at the subsequent stage is a voltage dividing circuit that divides a signal by a resistance ratio of a resistor R5a (hereinafter also referred to as a third resistor) and a resistor R5b (hereinafter also referred to as a fourth resistor) , and connects the resistors R5a and R5b. The point becomes the output of the attenuator 5. The resistance values of the resistors R5a and R5b are 200 [kΩ] and 22.7 [kΩ], for example. The attenuator 5 is provided between the changeover switches SW6a and SW6b, divides and attenuates the signal from the switch SW6a according to the resistance ratio of the resistors R5a and R5b, and transmits the attenuated signal to the switch SW6b. The resistor R5a is provided on the signal line L9, and the resistor R5b is provided between the signal line L9 and the ground.

信号線Ｌ１０は、減衰比１／１であって、信号線Ｌ９と並列に設けられ、抵抗Ｒ６（以下第５の抵抗ともいう）を介してグランドに接地される。なお、抵抗Ｒ６の抵抗値は２２２［ｋΩ］である。 The signal line L10 has an attenuation ratio of 1/1, is provided in parallel with the signal line L9, and is grounded via a resistor R6 (hereinafter also referred to as a fifth resistor) . The resistance value of the resistor R6 is 222 [kΩ].

第２の切替スイッチＳＷ６ａ、ＳＷ６ｂは、連動して切替を行ない、信号線Ｌ９または信号線Ｌ１０を択一的に選択し、選択した信号線Ｌ９，Ｌ１０を介して入力側の切替スイッチＳＷ５ａからの電気信号を出力側の切替スイッチＳＷ５ｂに伝送させる。   The second change-over switches SW6a and SW6b are switched in conjunction with each other to selectively select the signal line L9 or the signal line L10 and from the input-side change-over switch SW5a via the selected signal lines L9 and L10. The electrical signal is transmitted to the output side switch SW5b.

より詳細には、スイッチＳＷ６ａの入力端が減衰器５の出力側に接続され、一方の出力端が信号線Ｌ９の一端（減衰器５の入力側）に接続され、他方の出力端が信号線Ｌ１０の一端に接続される。スイッチＳＷ６ｂの一方の入力端が信号線Ｌ９の他端（減衰器５の出力側）に接続され、他方の入力端が信号線Ｌ１０の他端に接続され、出力端が切替スイッチＳＷ５ｂの他方の入力端に接続される。   More specifically, the input end of the switch SW6a is connected to the output side of the attenuator 5, one output end is connected to one end of the signal line L9 (input side of the attenuator 5), and the other output end is connected to the signal line. Connected to one end of L10. One input end of the switch SW6b is connected to the other end of the signal line L9 (the output side of the attenuator 5), the other input end is connected to the other end of the signal line L10, and the output end is the other end of the changeover switch SW5b. Connected to the input end.

抵抗Ｒ０（以下第６の抵抗ともいう）は、出力端子Ｐｏとグランド間に設けられ、抵抗値は１［ＭΩ］である。
なお、各抵抗の抵抗値は、どのような値でもよく、第１の切替スイッチＳＷ５ａ、ＳＷ５ｂおよび第２の切替スイッチＳＷ６ａ、ＳＷ６ｂの接続に関わらず、つまり、減衰量１／１、１／１０、１／１００に関わらず、入力インピーダンスが１［ＭΩ］と一定になるような抵抗値を組み合わせればよい。 The resistor R0 (hereinafter also referred to as a sixth resistor) is provided between the output terminal Po and the ground, and has a resistance value of 1 [MΩ].
The resistance value of each resistor may be any value, regardless of the connection of the first change-over switches SW5a and SW5b and the second change-over switches SW6a and SW6b, that is, the attenuation amounts 1/1 and 1/10. Regardless of 1/100, a resistance value that makes the input impedance constant at 1 [MΩ] may be combined.

このような装置の動作を説明する。
減衰量（入力信号の振幅に対する出力信号の振幅の大きさ）を１／１とする場合（図１参照）、切替スイッチＳＷ５ａ、ＳＷ５ｂが、接続を切り替えて信号線Ｌ７を選択する。この際、切替スイッチＳＷ６ａ、６ｂの接続はどのような状態であってもよい。これにより、入力端子Ｐｉ、信号線Ｌ７，出力端子Ｐｏが電気的に接続され、入力端子Ｐｉからの電気信号が、減衰量１／１で出力端子Ｐｏに伝送される。もちろん、入力インピーダンスは、１［ＭΩ］である。 The operation of such an apparatus will be described.
When the attenuation amount (the amplitude of the output signal with respect to the amplitude of the input signal) is 1/1 (see FIG. 1), the change-over switches SW5a and SW5b switch the connection and select the signal line L7. At this time, the connection of the changeover switches SW6a and 6b may be in any state. Thereby, the input terminal Pi, the signal line L7, and the output terminal Po are electrically connected, and the electric signal from the input terminal Pi is transmitted to the output terminal Po with an attenuation of 1/1. Of course, the input impedance is 1 [MΩ].

減衰量を１／１０とする場合（図２参照）、切替スイッチＳＷ５ａ、ＳＷ５ｂが、接続を切り替えて信号線Ｌ８を選択し、切替スイッチＳＷ６ａ、ＳＷ６ｂが、接続を切り替えて信号線Ｌ１０を選択する。これにより、入力端子Ｐｉ、信号線Ｌ８，Ｌ１０，出力端子Ｐｏが電気的に接続される。そして、入力端子Ｐｉからの電気信号の信号レベルが、減衰器４によって１／１０に減衰されて出力端子Ｐｏに伝送される。   When the attenuation is 1/10 (see FIG. 2), the change-over switches SW5a and SW5b switch the connection and select the signal line L8, and the change-over switches SW6a and SW6b switch the connection and select the signal line L10. . As a result, the input terminal Pi, the signal lines L8 and L10, and the output terminal Po are electrically connected. The signal level of the electrical signal from the input terminal Pi is attenuated to 1/10 by the attenuator 4 and transmitted to the output terminal Po.

この際、入力インピーダンスは、抵抗Ｒ０、Ｒ４ａ、Ｒ４ｂ，Ｒ６の合成抵抗となり、約１［ＭΩ］である。すなわち、後段の減衰器５に対するスルー用の信号線Ｌ１０に抵抗Ｒ６を設けることにより、図６と比較して、初段の減衰器４の抵抗Ｒ４ｂの抵抗値を大きくできる。なお、出力側（出力端子Ｐｏ）からみた出力インピーダンスは、約１１１［ｋΩ］であり、図６とほとんど変わらず、ノイズ特性が悪化することも無い。   At this time, the input impedance is a combined resistance of the resistors R0, R4a, R4b, and R6, and is about 1 [MΩ]. That is, the resistance value of the resistor R4b of the first-stage attenuator 4 can be increased by providing the resistor R6 on the through signal line L10 for the latter-stage attenuator 5 as compared with FIG. The output impedance viewed from the output side (output terminal Po) is about 111 [kΩ], which is almost the same as in FIG. 6, and the noise characteristics are not deteriorated.

減衰量を１／１００とする場合（図３参照）、切替スイッチＳＷ５ａ、ＳＷ５ｂが、接続を切り替えて信号線Ｌ８を選択し、切替スイッチＳＷ６ａ、ＳＷ６ｂが、接続を切り替えて信号線Ｌ９を選択する。これにより、入力端子Ｐｉ、信号線Ｌ８，Ｌ９，出力端子Ｐｏが電気的に接続される。そして、入力端子Ｐｉからの電気信号の信号レベルが、初段の減衰器４によって１／１０に減衰され、後段の減衰器５によって更に１／１０に減衰され、全体として入力信号に対して１／１００に減衰されて出力端子Ｐｏに伝送される。   When the attenuation is 1/100 (see FIG. 3), the change-over switches SW5a and SW5b switch the connection and select the signal line L8, and the change-over switches SW6a and SW6b switch the connection and select the signal line L9. . As a result, the input terminal Pi, the signal lines L8 and L9, and the output terminal Po are electrically connected. Then, the signal level of the electric signal from the input terminal Pi is attenuated to 1/10 by the first-stage attenuator 4, further attenuated to 1/10 by the subsequent-stage attenuator 5, and as a whole, 1 / The signal is attenuated to 100 and transmitted to the output terminal Po.

この際、入力インピーダンスは、抵抗Ｒ０、Ｒ４ａ、Ｒ４ｂ、Ｒ５ａ、Ｒ５ｂの合成抵抗となり、約１［ＭΩ］である。また、出力側（出力端子Ｐｏ）からみた出力インピーダンスも、抵抗Ｒ０、Ｒ４ａ、Ｒ４ｂ，Ｒ５ａ、Ｒ５ｂの合成抵抗となるが、１／１００の経路の信号線Ｌ９とグランド間の抵抗Ｒ５ｂが支配的であり、約２０［ｋΩ］程度になる。すなわち、初段の減衰器４の抵抗Ｒ４ｂの抵抗値を大きくとることができるため（スルー用の信号線Ｌ１０の抵抗Ｒ６があるため）、後段の抵抗Ｒ５ｂの抵抗値を小さく（（抵抗Ｒ０の抵抗値＞＞抵抗Ｒ５ｂの抵抗値））することができる。   At this time, the input impedance is a combined resistance of the resistors R0, R4a, R4b, R5a, and R5b, and is about 1 [MΩ]. The output impedance viewed from the output side (output terminal Po) is also a combined resistance of the resistors R0, R4a, R4b, R5a, and R5b, but the resistance R5b between the signal line L9 and the ground in the 1/100 path is dominant. It is about 20 [kΩ]. That is, since the resistance value of the resistor R4b of the first-stage attenuator 4 can be increased (because there is a resistor R6 of the through signal line L10), the resistance value of the subsequent-stage resistor R5b is decreased ((the resistance of the resistor R0). Value >> resistance value of resistor R5b)).

このように、減衰器無しの経路（信号線Ｌ７）を、減衰器有りの経路（信号線Ｌ８）全体に対して並列にする。そして、減衰器ありの経路（信号線Ｌ８）上に減衰比１／１０の減衰器４、５の２段を配置することにより、後段の減衰器５に対するスルー用の経路（装置全体の減衰量１／１０で用いる信号線Ｌ１０）に抵抗Ｒ６を設けても入力インピーダンスを１［ＭΩ］に保つことができる。さらに、図６と異なり、スルー用の経路（信号線Ｌ１０）に抵抗Ｒ６を設けるので、入力インピーダンスを１［ＭΩ］を保ったままで、減衰量１／１００で用いる減衰器５の抵抗Ｒ５ｂの抵抗値を小さくできる。これにより、大きな減衰量（図１では１／１００）であっても出力インピーダンスを小さくできると共に、２段の減衰器４、５で入力信号を減衰するので各減衰器４、５の分圧比を小さくでき、高周波数領域でも信号の劣化を抑えることができる。従って、大きな減衰量であってもノイズの影響等を少なくし、広帯域にわたって入力信号の波形の劣化を抑えることができる。   In this way, the path without the attenuator (signal line L7) is parallel to the entire path with the attenuator (signal line L8). Then, by arranging two stages of attenuators 4 and 5 having an attenuation ratio of 1/10 on a path with an attenuator (signal line L8), a through path (attenuation amount of the entire apparatus) for the attenuator 5 at the subsequent stage is arranged. Even if the resistor R6 is provided on the signal line L10) used for 1/10, the input impedance can be kept at 1 [MΩ]. Further, unlike FIG. 6, since the resistor R6 is provided in the through path (signal line L10), the resistance of the resistor R5b of the attenuator 5 used with an attenuation of 1/100 while maintaining the input impedance of 1 [MΩ]. The value can be reduced. As a result, the output impedance can be reduced even with a large attenuation (1/100 in FIG. 1), and the input signal is attenuated by the two-stage attenuators 4 and 5. It is possible to reduce the signal degradation even in a high frequency region. Therefore, even if the amount of attenuation is large, the influence of noise and the like can be reduced, and deterioration of the waveform of the input signal can be suppressed over a wide band.

［第２の実施例］
図４は、本発明の第２の実施例を示した構成図である。図１と同一のものには同一符号を付し、説明を省略する。図４は、１／１、１／１０、１／１００の減衰量の代わりに、所望の減衰比とする構成を示した例である。 [Second Embodiment]
FIG. 4 is a block diagram showing a second embodiment of the present invention. The same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted. FIG. 4 shows an example in which a desired attenuation ratio is used instead of the attenuation of 1/1, 1/10, and 1/100.

図４において、入力端子Ｐｉと入力側の切替スイッチＳＷ５ａの信号線上に抵抗Ｒ７（以下第７の抵抗ともいう）が新たに設けられる。ここで、抗Ｒ７と抵抗Ｒ０との抵抗比を選ぶことにより、減衰量１／１でなく、所望の減衰量とすることができる。
In FIG. 4, a resistor R7 (hereinafter also referred to as a seventh resistor) is newly provided on the signal line of the input terminal Pi and the input side changeover switch SW5a. Here, by selecting the resistance ratio between the resistance R7 and the resistance R0, it is possible to obtain a desired attenuation amount instead of the attenuation amount 1/1.

図４では、抵抗Ｒ０（８００［ｋΩ］）、抵抗Ｒ７（２００［ｋΩ］）との分圧によって定分圧とし、最も少ない減衰量が８／１０となる。その他の抵抗は、入力インピーダンスが１［ＭΩ］となるように、例えば、抵抗Ｒ４ａ＝７２０［ｋΩ］、抵抗Ｒ４ｂ＝１７８［ｋΩ］、抵抗Ｒ５ａ＝１３１［ｋΩ］、抵抗Ｒ５ｂ＝１４．８［ｋΩ］、抵抗Ｒ６＝１７８［ｋΩ］とする構成例である。   In FIG. 4, a constant partial pressure is obtained by the partial pressure of the resistor R0 (800 [kΩ]) and the resistor R7 (200 [kΩ]), and the smallest attenuation is 8/10. The other resistors are, for example, a resistor R4a = 720 [kΩ], a resistor R4b = 178 [kΩ], a resistor R5a = 131 [kΩ], and a resistor R5b = 14.8 [1] so that the input impedance is 1 [MΩ]. kΩ] and resistance R6 = 178 [kΩ].

このような装置の動作は、図１に示す装置とほぼ同様であるが、スイッチＳＷ５ａ前段の抵抗Ｒ７とスイッチＳＷ５ａより後段の抵抗との抵抗比により、図１に示す装置での１／１、１／１０、１／１００であった入力信号に対する減衰量が、８／１０、８／１００、８／１０００になる。   The operation of such a device is almost the same as that of the device shown in FIG. 1, but 1/1 in the device shown in FIG. 1, depending on the resistance ratio between the resistor R7 before the switch SW5a and the resistor after the switch SW5a. Attenuation amounts for input signals that were 1/10 and 1/100 are 8/10, 8/100, and 8/1000.

なお、本発明はこれに限定されるものではなく、以下に示すようなものでもよい。
（１）図１に示す装置において、１／１、１／１０、１／１００の３種類で入力信号を減衰させる構成を示したが、信号を減衰させない経路１／１が不要の場合、つまり、減衰量が１／１０、１／１００の２種類の場合、信号線Ｌ７、第１の切替スイッチＳＷ５ａ、ＳＷ５ｂは不要である。図２でも同様である。 The present invention is not limited to this, and may be as shown below.
(1) In the apparatus shown in FIG. 1, the configuration in which the input signal is attenuated by three types of 1/1, 1/10, and 1/100 is shown. However, when the path 1/1 that does not attenuate the signal is unnecessary, that is, In the case of two types of attenuation of 1/10 and 1/100, the signal line L7 and the first change-over switches SW5a and SW5b are not necessary. The same applies to FIG.

（２）図１に示す装置において、減衰量１／１での入力インピーダンス１［ＭΩ］の例を示したが、その他の抵抗Ｒ４ａ、Ｒ４ｂ、Ｒ５ａ、Ｒ５ｂ、Ｒ６の抵抗値は、各減衰量１／１０、１／１００における合成抵抗値（入力インピーダンス）が約１［ＭΩ］となればよく、どのような抵抗値を組合せてもよい。また、入力インピーダンスは特に１［ＭΩ］にこだわる必要はなく、どのような値でもよい。 (2) In the apparatus shown in FIG. 1, an example of input impedance 1 [MΩ] at an attenuation of 1/1 is shown. However, the resistance values of the other resistors R4a, R4b, R5a, R5b, and R6 are the attenuation values. The combined resistance value (input impedance) at 1/10 and 1/100 only needs to be about 1 [MΩ], and any resistance value may be combined. Further, the input impedance does not have to be particularly 1 [MΩ], and may be any value.

（３）図１、図２に示す装置において、信号線Ｌ８に初段の減衰器４、後段の減衰器５の２個の減衰器を設ける構成を示したが、複数個の減衰器を設けてよい。例えば、３個にする場合、後段の減衰器５と第２の切替スイッチＳＷ６ｂの間に、減衰器を持つ信号線とスルー用の信号線（抵抗を介して接地させる）とを並列に設け、切替スイッチで接続を択一的に行なうとよい。 (3) In the apparatus shown in FIG. 1 and FIG. 2, the configuration in which two attenuators, the first-stage attenuator 4 and the second-stage attenuator 5 are provided on the signal line L8, but a plurality of attenuators are provided. Good. For example, in the case of three, a signal line having an attenuator and a through signal line (grounded through a resistor) are provided in parallel between the attenuator 5 at the subsequent stage and the second changeover switch SW6b. It is advisable to use a change-over switch for connection.

本発明の第１の実施例（減衰量１／１）を示した構成図である。It is the block diagram which showed the 1st Example (attenuation amount 1/1) of this invention. 図１に示す装置で減衰量１／１０の場合の実施例を示した構成図である。It is the block diagram which showed the Example in the case of attenuation amount 1/10 with the apparatus shown in FIG. 図１に示す装置で減衰量１／１００の場合の実施例を示した構成図である。It is the block diagram which showed the Example in the case of attenuation amount 1/100 with the apparatus shown in FIG. 本発明の第２の実施例を示した構成図である。It is the block diagram which showed the 2nd Example of this invention. 従来の可変減衰装置の構成を示した図である。It is the figure which showed the structure of the conventional variable attenuation apparatus. 従来の可変減衰装置のその他の構成を示した図である。It is the figure which showed the other structure of the conventional variable attenuation apparatus.

符号の説明Explanation of symbols

４ 初段の減衰器
５ 後段の減衰器
Ｐｉ 入力端子
Ｐｏ 出力端子
Ｌ７〜Ｌ１０ 信号線
Ｒ０、Ｒ４ａ、Ｒ４ｂ，Ｒ５ａ、Ｒ５ｂ，Ｒ６，Ｒ７ 抵抗
ＳＷ５ａ、ＳＷ５ｂ、ＳＷ６ａ、ＳＷ６ｂ 切替スイッチ 4 First-stage attenuator 5 Second-stage attenuator Pi input terminal Po output terminal L7 to L10 Signal lines R0, R4a, R4b, R5a, R5b, R6, R7 Resistors SW5a, SW5b, SW6a, SW6b Changeover switch

Claims (4)

入力端子に入力された電気信号を減衰して出力端子から出力する可変減衰装置において、
前記入力端子からの電気信号を、第１の抵抗と第２の抵抗の抵抗比で分圧して減衰させる初段の減衰器と、
前記初段の減衰器からの電気信号を、第３の抵抗と第４の抵抗の抵抗比で分圧して減衰させて前記出力端子に出力する後段の減衰器と、
前記後段の減衰器に並列に設けられ、第５の抵抗を介して接地されている信号線と、
前記後段の減衰器または前記信号線の一方を選択し、選択した後段の減衰器または信号線を介して、前記初段の減衰器からの出力を前記出力端子に伝送させる一対の切替スイッチと、
前記出力端子とグランドとの間に設けられる第６の抵抗とを設け、
前記初段の減衰器は、前記第１の抵抗が本減衰器の入力側と出力側との間に、前記第２の抵抗が本減衰器の出力側とグランドとの間に設けられ、
前記後段の減衰器は、前記第３の抵抗が本減衰器の入力側と出力側との間に、前記第４の抵抗が本減衰器の出力側とグランドとの間に設けられることを特徴とする可変減衰装置。 In the variable attenuation device that attenuates the electrical signal input to the input terminal and outputs it from the output terminal,
A first-stage attenuator that divides and attenuates the electrical signal from the input terminal by a resistance ratio of the first resistor and the second resistor;
A subsequent- stage attenuator that divides and attenuates the electrical signal from the first-stage attenuator by a resistance ratio of a third resistor and a fourth resistor and outputs the divided signal to the output terminal;
Provided in parallel to the latter stage of the attenuator, a signal line is grounded via a fifth resistor,
A pair of changeover switches for selecting one of the subsequent attenuator or the signal line and transmitting the output from the first attenuator to the output terminal via the selected subsequent attenuator or signal line;
A sixth resistor provided between the output terminal and the ground;
In the first-stage attenuator, the first resistor is provided between the input side and the output side of the attenuator, and the second resistor is provided between the output side of the attenuator and the ground.
In the attenuator at the rear stage, the third resistor is provided between the input side and the output side of the attenuator, and the fourth resistor is provided between the output side of the attenuator and the ground. A variable attenuation device. 入力端子に入力された電気信号を減衰して出力端子から出力する可変減衰装置において、
第１の経路と、
前記第１の経路と並列に設けられ、前記電気信号を抵抗で分圧して減衰させる減衰器を複数有する第２の経路と、
前記第１の経路または第２の経路の一方を選択し、選択した経路を介して前記入力端子からの電気信号を前記出力端子に伝送させる一対の第１の切替スイッチと、
前記出力端子とグランドとの間に設けられる第６の抵抗とを設け、
前記第２の経路は、
前記入力端子からの電気信号を、第１の抵抗と第２の抵抗の抵抗比で分圧して減衰させる初段の減衰器と、
前記初段の減衰器からの電気信号を、第３の抵抗と第４の抵抗の抵抗比で分圧して減衰させて前記出力端子に出力する後段の減衰器と、
前記後段の減衰器に並列に設けられ、第５の抵抗を介して接地されている信号線と、
前記後段の減衰器または前記信号線の一方を選択し、選択した後段の減衰器または信号線を介して、前記初段の減衰器からの出力を出力側の前記第１の切替スイッチに伝送させる一対の第２の切替スイッチとを備え、
前記初段の減衰器は、前記第１の抵抗が本減衰器の入力側と出力側との間に、前記第２の抵抗が本減衰器の出力側とグランドとの間に設けられ、
前記後段の減衰器は、前記第３の抵抗が本減衰器の入力側と出力側との間に、前記第４の抵抗が本減衰器の出力側とグランドとの間に設けられることを特徴とする可変減衰装置。 In the variable attenuation device that attenuates the electrical signal input to the input terminal and outputs it from the output terminal,
A first path;
A second path provided in parallel with the first path, and having a plurality of attenuators that divide and attenuate the electrical signal by a resistor;
A pair of first changeover switches for selecting one of the first path or the second path and transmitting an electrical signal from the input terminal to the output terminal via the selected path;
A sixth resistor provided between the output terminal and the ground;
The second route is:
A first-stage attenuator that divides and attenuates the electrical signal from the input terminal by a resistance ratio of the first resistor and the second resistor;
A subsequent- stage attenuator that divides and attenuates the electrical signal from the first-stage attenuator by a resistance ratio of a third resistor and a fourth resistor and outputs the divided signal to the output terminal;
Provided in parallel to the latter stage of the attenuator, a signal line is grounded via a fifth resistor,
A pair that selects one of the latter-stage attenuator or the signal line and transmits the output from the first-stage attenuator to the first change-over switch on the output side via the selected latter-stage attenuator or signal line. A second changeover switch,
In the first-stage attenuator , the first resistor is provided between the input side and the output side of the attenuator, and the second resistor is provided between the output side of the attenuator and the ground.
In the attenuator at the rear stage, the third resistor is provided between the input side and the output side of the attenuator, and the fourth resistor is provided between the output side of the attenuator and the ground. A variable attenuation device. 一端が前記入力端子に接続され、他端が入力側の前記第１の切替スイッチに接続される分圧用の第７の抵抗を設けたことを特徴とする請求項２記載の可変減衰器。   The variable attenuator according to claim 2, further comprising a seventh resistor for voltage division whose one end is connected to the input terminal and the other end is connected to the first selector switch on the input side. 入力インピーダンスが減衰量によらず一定となることを特徴とする請求項１〜３のいずれかに記載の可変減衰装置。   4. The variable attenuation device according to claim 1, wherein the input impedance is constant regardless of the attenuation.
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