JPS6278905A - Attenuator switching circuit - Google Patents

Abstract

PURPOSE:To constituted the changeover switch of the attenuator as one circuit and to simplify the structure of an attenuator switching circuit by connecting all divided resistances for attenuating an input signal in series and connecting capacitors to the respective resistances in parallel, and leading signals out of between the resistances. CONSTITUTION:A voltage impressed from an input terminal 1 is AC-coupled, DC-coupled, or ground(G)-coupled and passed through an AC-G-DC coupling switch SW 2 before inputted to the attenuator. The resistances R1-Rn are interposed in series between the input part and ground of a next attenuator part, and the ratio of their resistance values is the attenuation rate of each range of the attenuator. Then, the capacitor C1-Cn are connected in parallel to the resistances R1-Rn so as to make frequency corrections. Input voltages which are attenuated among the resistances R1-Rn according to respective attenuation ratios are connected to respective contact points of a range SW 3. The voltage leg out of the common terminal of the range SW is inputted to an amplifier part 4 and amplified with a constant gain up to a level that its following stage requires.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an attenuator switching circuit.

[Summary of the invention]

The present invention is an attenuator switching circuit in which dividing resistors for attenuating an input signal are all connected in series, a capacitor is connected in parallel to each resistor, and the attenuated signal is extracted from between the resistors. is made into one circuit.

[Conventional technology]

As shown in Figure 2, conventional attenuator switching circuits attenuate the input voltage by combining several dividing resistors and several dividing circuits each with frequency correction using capacitors connected in parallel. switch 1
1, j2, and 13.14.

[Problems and Objects to be Solved by the Invention] However, the above-mentioned prior art has a problem in that vl number of switching contacts are required for each switching position.

The present invention is intended to solve this problem, and its purpose is to simplify the structure of the attenuator circuit by integrating the attenuator changeover switch into one circuit.

[Means for solving problems]

The 7-tensioner circuit of the present invention includes a plurality of resistors connected in series to attenuate an input signal, a capacitor connected in parallel to each resistor, and a changeover switch between each resistor to take out the attenuated signal. It is characterized by consisting of.

〔Example〕

#! Figure 1 shows 7 of the oscilloscope in an embodiment of the present invention.
FIG. 2 is a circuit diagram of a power supply circuit.

1 is the input terminal, and the voltage applied from here is AC-coupled, DC-coupled, or grounded (G
) bond, and the A C-G-D C bond of 2'1WXt
- Pass.

In the next attenuator section, there is a resistor R8 between the input section and ground.
~Rn are connected in series, and the ratio of their resistance values becomes the attenuation ratio of each range of the attenuator. Here, the total sum of resistors R8 to Rn is set to 1MΩ, and the input impedance is set to 1MΩ. Furthermore, since the accuracy of the attenuation ratio is determined by the accuracy of these resistors, it is also possible to use semi-fixed resistors.

However, since there is a problem with the frequency characteristics if left as is, stomach wave number correction is performed. -〇n. This is because the attenuation rate becomes uneven depending on the frequency due to the contact capacitance of the range switch (5), the input capacitance of the amplifier section (4), the wiring on the board, the floating resistance between the fixed resistor and the ground, etc. A resistor R is placed in parallel with the resistor to form a bridge, and by balancing this bridge, the attenuation ratio is not affected by frequency.
The input voltages attenuated by the respective attenuation ratios from between ~Rn are connected to the respective contacts of the 3 range SWs. And the voltage taken out from the common terminal of this range i9W is 4
The signal goes into the amplifier section and is amplified at a constant gain to the required level in the subsequent stage.

With such an attenuator switching circuit, even if the number of switching ranges increases to a certain extent, it can be configured by using only a single circuit multi-contact switch.

〔Effect of the invention〕

As described above, according to the present invention, since the range SW is a single circuit, the mounting area of the SWs can be reduced compared to conventional systems that require multiple circuits, and the input impedance By holding constant and performing frequency correction, there is an effect that stable attenuation can be obtained with respect to the characteristics between each range and the measurement frequency.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the attenuator circuit of the present invention. FIG. 2 is a circuit diagram of a conventional attenuator circuit. 1...Input terminal 2...AC-G-DC coupling SW4...
Above the amplifier section

Claims (1)

[Claims] An attenuator switching circuit comprising a plurality of resistors connected in series to attenuate an input signal, a capacitor connected in parallel to each resistor, and a changeover switch to take out the attenuated signal from between each resistor. .