JPS5931054Y2 - equivalent inductance circuit - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an equivalent inductance circuit in which inductance is obtained by an electronic circuit without using a coil.

Conventionally, coils have been used to obtain inductance; air-core coils have been used to obtain relatively small inductances, and iron-core coils have been used to obtain large inductances.

However, coils with iron cores in particular have various drawbacks such as being large in size, heavy in weight, expensive, easy to pick up noise, generate loud noise, and have large loss due to DC voltage drop. The circuit design top was also one of the parts that was difficult to use.

In view of the above-mentioned circumstances, this invention provides an equivalent inductance circuit in which the inductance is obtained by an electronic circuit without using a coil, and the first input terminal is connected via a first resistor to an inverting or non-inverting inductance circuit. A second input terminal is connected to one input terminal of an amplifier having both input terminals, a second input terminal is connected to the other input terminal of the amplifier through a second resistor, and a voltage between the one input terminal and the output terminal of the amplifier is connected to one input terminal of an amplifier having both input terminals. A third resistor and a capacitor are inserted in parallel to the amplifier, and a fourth resistor is inserted between the other input terminal and the output terminal of the amplifier.

Hereinafter, embodiments of this invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram showing a known negative impedance conversion circuit, and FIG. 2 is a circuit diagram showing an equivalent inductance circuit of this invention using the negative impedance conversion circuit shown in FIG. FIG. 1 is a circuit diagram of an embodiment of the invention.

In the negative impedance circuit shown in FIG. 1, an input terminal 1 is connected to one input terminal of an amplifier 2. An impedance element 3 (impedance [z,) is interposed between one input terminal and the output terminal of this amplifier 2. The other input terminal of the amplifier 2 is connected to the impedance element 4 (impedance ft1z3
), and an impedance element 5 (impedance ff1z2) is inserted between the other input terminal and output terminal of the amplifier 2.

When an input signal of voltage V is applied to input terminal 1, the input current is 13, and the output voltage is .

, if the current flowing through the impedance element 4 is i2, then (
However, current 11. The direction of y12 is shown in Figure 1).

An equation consisting of equations (1) and (2) is obtained, and by substituting equation (3) into equation (4), the following equation is obtained.

Therefore, if the impedance seen from the input terminal 1 to the amplifier 2 side is Zi, the relationship represented by the above equation (5) can be obtained.

Next, an embodiment of this invention shown in FIG. 2 will be described.

In the embodiment shown in FIG. 2, the first input terminal 11a is connected to the resistor 1.
2 ([direct R1) (first resistor) to one input terminal of the amplifier 13, the second input terminal 11b is grounded, and between the one input terminal and the output terminal of the amplifier 13, Resistor 14 (value R2) (third resistor), capacitor 15 (
value C) is inserted in parallel, the other input of the amplifier 13 is grounded via a resistor 16 (value R,) (second resistor),
Furthermore, a resistor 17 (f
12) (fourth resistor) is inserted.

The circuit shown in FIG. 2 is constructed by inserting a resistor 14 and a capacitor 15 connected in parallel as the impedance element 3 in the circuit shown in FIG. 1, and inserting a resistor 16 as the impedance element 4.
5, a resistor 1T is inserted, and a resistor 12 is further connected to the outside of the input terminal 1. Therefore, the impedance Zll when looking at the amplifier 13 side from the first and second input terminals 11a and llb is zi = R+zi ・・・・・・ (7
)1.

Here, in Zlt Z2y Z3 in the above formula (6), Zl = C/ R2s Z2 ”” R2, z3:=R
.

After substituting each, by substituting equation (6) into equation (7), we get
By calculating the right side of this equation (8), the input impedance zi1 of the circuit shown in FIG. 2 can be obtained as follows (However, in this equation (9), S=jω).

By the way, the composite impedance z12 of the parallel circuit of the resistor 20 (value R) and the coil 21 (inductance L) as shown in FIG. It can be seen from this that the circuit shown in FIG. 2 can be represented by a parallel circuit of a resistor and a coil shown in FIG. 3 in an equi-polarized manner.

However, in this case, it is necessary that the following relationship holds true.

That is, in the circuit shown in FIG. 2, the impedance between the first and second input terminals 11a and llb is equivalent to an equivalent inductance with an inductance component,
Further, the inductance portion is determined from the value R4 of the resistors 12 and 16, the value R2 of the resistors 14 and 17, and the value C of the capacitor 15 according to the above equation (11).

Note that the input polarity of the amplifier 13 in the circuit shown in FIG. However, if the first input terminal 11a is likely to be open during use, or if a negative impedance is connected between the first and second input terminals 11a; In these cases, the amplifier 1 is connected to the first input terminal 11a.
It is necessary to use the inverting input terminal of 3.

Figures 4 and 5 show examples of how this invention is used.
FIG. 4 shows an example in which this invention is used as an inductance in a filter circuit, and FIG. 5 shows an example in which this invention is used in a DC bias circuit of an amplifier composed of bipolar transistors.

In the figure, LC indicates an equivalent inductance circuit according to this invention.

In particular, the method of use shown in FIG. 5 is one of the very useful methods of use because the input side of the amplifier can be directly connected to the previous stage without using a coupling capacitor.

As explained above, according to this invention, equivalent inductance was realized from the amplifier, resistor, and capacitor, so
A large inductance can be obtained at low cost with a small-shaped component, the size of the inductance can be arbitrarily set over a wide range, it is not affected by external electromagnetic induction, and is therefore resistant to hum and noise. It has the effect of not generating noise, and is suitable for filter circuits, bipolar
It can be widely used in circuits that use inductance, such as DC bias circuits for amplifiers using transistors, and oscillators.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing an example of a conventional negative impedance conversion circuit, Fig. 2 is a circuit diagram showing an embodiment of this invention, and Fig. 3 is a circuit diagram showing an example of the embodiment shown in Fig. 2. FIGS. 4 and 5 are circuit diagrams showing an example of the use of this invention. 11a...first input terminal, 11b...
・Second input terminal, 12...First resistor (resistance), 13...Amplifier, 14...Third resistor (resistance), 15... ...Capacitor, 16...
...Second resistance (resistance), 11...Fourth resistance.

Claims (1)

[Scope of utility model registration request] , the first input terminal is connected to one input terminal of an amplifier having both inverting and non-inverting input terminals via a first resistor, and the noodle 2
A third resistor and a capacitor are inserted in parallel between the one input terminal and the output terminal of the amplifier; A fourth resistor is inserted between the other input terminal and the output terminal, and the impedance between the first and second input terminals has an inductance component equal to the number of songs. Equivalent inductance circuit.