JPH0333017Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to a measurement signal supply circuit for a circuit element measuring instrument that measures resistance, capacitors, coils, etc.

[Prior Art] Next, the configuration of a measurement signal supply circuit according to the prior art will be explained with reference to FIG. 1 in Fig. 1 is a signal source,
2 is a transformer, 3 is a circuit element to be measured, 4 is an amplifier, 5 is a reference resistor, 6 is a voltage terminal, and 7 is a current terminal.

In FIG. 1, a signal from a signal source 1 is applied from a transformer 2 to a circuit element 3, the voltage applied to the circuit element 3 is measured at a voltage terminal 6, and the current flowing through the circuit element 3 is measured at a current terminal 7. Then, the impedance of the circuit element 3 is determined from the measured values of the voltage terminal 6 and the current terminal 7. That is, 1 and 2 constitute a measurement signal supply circuit, and 4 to 7 constitute a measurement circuit for the circuit element 3.

The reason why the transformer 2 is inserted between the signal source 1 and the circuit element 3 is to remove command mode noise superimposed on the signal source 1.

[Problems to be solved by the invention] In FIG. 1, it is difficult to measure the circuit element 3 over a wide band. The reason is that it is necessary to electrostatically shield transformer 2, but when electrostatically shielded, the coupling between the primary and secondary of transformer 2 deteriorates.
This is because the wide area characteristics deteriorate.

This idea replaces the transformer 2 in Figure 1 with 2
The purpose of this system is to use a transformer of this type to widen the bandwidth of the measurement circuit.

[Means for Solving the Problem] In order to achieve this object, this invention uses a two-winding transformer consisting of a resistor 8 connected to the signal source 1, and a first winding and a second winding. 9, the resistor 9 has a resistance value equal to the characteristic impedance of the two-winding transformer 9, the first terminal of the first winding is connected to the resistor 8, and the second terminal of the first winding is connected to the resistor 8. is connected to the measuring circuit, the third terminal of the second winding is connected to the ground of the signal source 1, and the fourth terminal of the second winding is connected to the ground of the measuring circuit.

Next, the configuration of the measurement signal supply circuit according to this invention will be explained with reference to FIG. 8 in Figure 2 is resistance, 9
is a two-winding transformer, and the other parts are the same as in Fig. 1. That is, in FIG. 2, the transformer 2 in FIG. 1 is replaced with a resistor 8 and a two-turn transformer 9.

The resistance value of the resistor 8 is made equal to the characteristic impedance of the two-winding transformer 9. When the circuit element 3 is connected, a reflected wave is generated, and the resistor 8 is made to act as a terminating resistor for this reflected wave.

In FIG. 2, since the two-winding transformer 9 is connected to both ends of the signal source 1, common mode noise superimposed on the signal source 1 can be canceled out. Furthermore, since the two-wound transformer 9 does not require an electrostatic shield, the signal from the signal source 1 can be applied to the circuit element 3 without attenuating the signal at high frequencies.

In order to prevent the signal source 1 side and the circuit element 3 side in FIG.
Of the two windings, one end of the winding to which the resistor 8 is not connected is connected to the ground of the signal source 1, and one end of the winding is connected to the ground of the amplifier 4 side.

[Effects of the invention] According to this invention, since a two-winding transformer and a resistor having a resistance value equal to the characteristic impedance of the two-winding transformer are used, noise superimposed on the signal source can be removed. In addition, it is possible to realize a wideband measurement circuit.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a measurement signal supply circuit according to the prior art, and FIG. 2 is a block diagram of a measurement signal supply circuit according to this invention. DESCRIPTION OF SYMBOLS 1...Signal source, 2...Transformer, 3...Circuit element to be measured, 4...Amplifier, 5...Reference resistance,
6...Voltage terminal, 7...Current terminal, 8...Resistance,
9...Two-volume transformer.

Claims (1)

[Claims for Utility Model Registration] A resistor connected to a signal source, and a two-winding transformer configured with a first winding and a second winding, the resistor having a characteristic of the two-winding transformer. The first coil of the first winding has a resistance value equal to the impedance.
is connected to the resistor, and the second terminal of the first winding is connected to the resistor.
The terminal of the third winding of the second winding is connected to the measuring circuit.
A measurement signal supply circuit for a circuit element measuring instrument, wherein a terminal of the second winding is connected to ground of the signal source, and a fourth terminal of the second winding is connected to ground of the measurement circuit.