KR20030014458A - A Frequency-Dependent Negative Resistance - Google Patents

Abstract

PURPOSE: A frequency-dependent negative resistor is provided to easily adjust current or voltage by changing a D-value of an FDNR using a TAA(trans-admittance amplifier) having a good frequency feature. CONSTITUTION: A non-inverting differentiator(121) is composed an operational amplifier(121a), a capacitor(C), and a resistor(R). A trans-admittance amplifier(TAA)(122a) receives a voltage from the non-inverting differentiator(121) and outputs an output feedback current. An input voltage(Vin) is connected to a positive input terminal of the operational amplifier(121a). The non-inverting differentiator(121) differentiates the input voltage to generate a differentiated voltage. The TAA(122a) generates the output feedback current based on the differentiated voltage from the non-inverting differentiator(121).

Description

Frequency-Dependent Negative Resistors

The present invention relates to a frequency-dependent negative resistance generator using a transadmittance amplifier (TAA), which is a voltage-to-current converter, and an operational amplifier, which is a voltage amplifier.

TAA used in the present invention is an amplifier that converts an input voltage into an output current, and the input / output transfer ratio is expressed as an admittance in which a function of frequency is used. The admittance of this TAA is controlled by a bias current, and because it is a current-mode circuit, it has a high frequency characteristic. The circuit symbol of this TAA is shown in FIG.

1A is a circuit symbol showing a TAA with a differential-input single-output, and FIG. 1B is a circuit symbol showing a TAA with a differential-input single-output. The relational expression as shown in Equation 1 is established between the input / output signals of the TAA having the differential-input single-output of FIG. 1A, and the relational expression as shown in Equation 2 between the input / output signals of the TAA having the differential-input differential-output of FIG. This holds true.

At this time, in order to apply TAA to a frequency-dependent negative resistor (FDNR), the output current of the TAA must not include a DC offset.

Frequency-Dependent Negative Resistance Generator (FDNR) is an active element whose impedance (resistance) changes with frequency, and is a building block that is the basis of the ladder type active filter configuration. Circuit. The impedance of a typical frequency-dependent negative resistor is Z = 1 / s ² D, where s ² is frequency dependent. That is, as s = jω and ω = 2πf, the change in frequency f causes the change in impedance Z.

Conventional frequency-dependent negative resistors are generally classified into floating type FDNR and ground type FDNR depending on the presence or absence of ground (terminal).

Figures 2a to 2c show a block diagram of a typical frequency-dependent negative resistor, which is a (differential) differentiator with a transfer function T (s) and a (differential) transadmittance element with a feedback current element. It consists of an amplifier. 2A is a grounded type FDNR inputting a single signal power supply, FIG. 2B is a floating type FDNR inputting a differential signal power supply, and FIG. 2C is a floating type FDNR inputting a single signal power supply. Fig. 2D shows circuit symbols of the grounded type FDNR and the floating type FDNR.

2A is a diagram illustrating a grounded type FDNR having a single input terminal and a single output terminal. The relation between the input voltage and the output voltage of this circuit is shown in Equation 3.

In addition, the input current I _in is expressed as in Equation (4).

Equation 4 representing the above input current I _in is expressed as an input impedance.

At this time, if the transfer function T (s) is represented again as in Equation 6.

Here, the admittance Ym is expressed as sC and the transfer function T (s) is realized as one differentiator.

2B is a diagram illustrating a floating FDNR having a differential input terminal and a differential output terminal. Differential transfer function in this circuit to be.

FIG. 2C illustrates a floating FDNR having a single input terminal and a single output terminal. The input current of the floating type FDNR having this single input terminal and single output terminal is expressed by Equation 7 below.

When expressed by the input impedance of this circuit, it is expressed as Equation 8 below.

When the transfer function T (s) is obtained from Equation 8, Equation 9 below.

As in Equation (9), the transadmittance Ym in the present invention is sC and the transfer function T (s) is realized with one differentiator and unit gain.

Conventional FDNR consists of a differential amplifier and a current feedback element using only an operational amplifier. Therefore, the circuit is complicated and the D value of the FDNR cannot be controlled by current or voltage, and the frequency characteristics of the operational amplifier cannot be used at high frequencies. There was a problem.

In order to solve the above problems of the prior art, the present invention provides a frequency-dependent negative resistor using TAA having a simple circuit configuration and easily adjusting the D value of the FDNR by varying a current or a voltage. Its purpose is to.

1A and 1B show symbols of a typical transadmittance amplifier (TAA),

2A-2C are block diagrams of a typical frequency-dependent negative resistor;

2d shows a symbol of a typical frequency-dependent negative resistor,

Figure 3a is a diagram showing a single differentiator using TAA,

3b is a diagram showing a differential differentiator using TAA;

4 is a circuit diagram of a grounded FDNR according to a first embodiment of the present invention;

5 is a circuit diagram of a floating FDNR according to a second embodiment of the present invention;

6 is a circuit diagram of a floating FDNR using three TAAs according to a third embodiment of the present invention;

7 is a circuit diagram of a grounded FDNR according to a fourth embodiment of the present invention;

8 is a circuit diagram of a grounded FDNR according to a fifth embodiment of the present invention;

9 is a circuit diagram of a grounded FDNR according to a sixth embodiment of the present invention;

10 is a circuit diagram of a grounded FDNR according to a seventh embodiment of the present invention;

11 is a circuit diagram of a grounded FDNR according to an eighth embodiment of the present invention;

12 is a circuit diagram of a grounded FDNR according to a ninth embodiment of the present invention;

13 is a circuit diagram of a grounded FDNR according to a tenth embodiment of the present invention;

14 is a circuit diagram illustrating a grounded FDNR according to an eleventh embodiment of the present invention.

Floating type frequency-dependent negative resistor according to the present invention for achieving the above object is a transadmittance amplifier for generating and outputting a current according to the input voltage, and outputting the differential voltage according to the current output from the transadmittance amplifier Differential means including a resistance element; And a current feedback means comprising a transadmittance amplifier for generating and outputting an output feedback current according to the differential voltage generated by the differential means.

In addition, the ground-type frequency-dependent negative resistor according to the present invention includes a voltage buffer for buffering the unit voltage to the input voltage and delivered to the rear stage, and a differential means including an operational amplifier for generating and outputting a differential voltage according to the input voltage; ; And a transadmittance amplifier which is a current feedback device for generating and outputting an output feedback current according to the differential voltage generated by the differential means.

In addition, the ground-type frequency-dependent negative resistor according to the present invention comprises: differential means including an operational amplifier for generating and outputting a differential voltage according to the input voltage; And a transadmittance amplifier which is a current feedback device that receives the differential voltage generated by the differentiating means to the negative input terminal, generates and outputs an output feedback current, and feeds the output feedback current to the positive input terminal.

In addition, the ground-type frequency-dependent negative resistor according to the present invention comprises: differential means including an operational amplifier for generating and outputting a differential voltage according to the input voltage; And a current transmitter which is a current feedback element for generating and outputting an output feedback current according to the differential voltage generated by the differential means.

Hereinafter, the "frequency-dependent negative resistor" according to an embodiment of the present invention will be described in detail.

Prior to describing a frequency-dependent negative resistor according to an embodiment of the present invention, a differentiator using TAA will be described first.

3A shows a single differentiator using TAA and FIG. 3B shows a differential differentiator using TAA. The principle of operation of these differentiators is the same: the TAA output current flows through resistor R to ground. TAA output current The output voltage of this differentiator is shown in Equation 10 below.

According to Equation 10, it can be seen that an inverted or non-inverted differentiator can be configured using TAA.

4 is a circuit diagram of a grounded type FDNR having a single input terminal and a single output terminal according to the first embodiment of the present invention. And a ground type FDNR is trans-admittance is Y _m1 of claim 1TAA (41a) and the transconductance is G _m is the transconductance amplifier (hereinafter, OTA ") differentiator (41) consisting of (41b), a trans-admittance of T _m2 And a current feedback element 42 made up of a second TAA 42a.

When the input voltage (V _in ) is input to the first TAA 41a, the output current is output from the first TAA 41a. Is generated and output. The generated current forms a differentiator 41 together with the OTA 41b serving as a resistance, and the differential voltage at this time is Becomes This differential voltage is again inputted to the second TAA 42a, which is the current feedback element 42, and the second TAA 42a outputs the output current. Outputs This output current is the output feedback current for forming the FDNR, and the input impedance expressing the relationship between the input voltage and the output feedback current is to be. In the equation representing the input impedance, the component s means frequency, which shows that the input impedance changes with frequency. The D value of this FDNR is shown in Equation 11 below.

Here, Y _m1 and Y _m2 are transadmittances of the first and second TAAs, and G _m is the transconductance of the OTAs. In the above Equation 11, if Y _m1 and Y _m2 are the same, Y _m1 = Y _m2 = Y _m = sC, to be.

The FDNR using TAA and OTA according to the present invention described above has the advantage of controlling the transconductance to electrically control the D value of the FDNR.

5 is a circuit diagram of a floating FDNR having a differential input terminal and a differential output terminal according to a second embodiment of the present invention. This floating type FDNR includes a differential differential 51 composed of a first TAA 51a having a transadmittance of Y _m1 and a resistor R, and a second feedback element 52 composed of a second TAA 52a having a transadmittance of Y _m2 . Include. Instead of a resistor, it can be configured by connecting an OTA with a transconductance of G _m .

When the input voltage V _in is input to the first TAA 51a, the first TAA 51a generates and outputs a current according to the input voltage, and the generated current is connected to the resistor R to connect the differentiator 51. Form. The differential voltage by this differentiator 51 becomes an output feedback current by T Aa 52a. Input impedance expressing the relationship between input voltage and output feedback current to be. Here, s means frequency, and the input impedance of the FDNR according to FIG. 5 also varies according to the frequency.

The D value of this FDNR is represented by Equation 12 when the resistor is connected, and is expressed by Equation 13 when the differential OTA is connected.

6 is a circuit diagram of a floating FDNR using three TAAs according to a third embodiment of the present invention. This is a current return consisting of a differential (61) consisting of a first TAA (61a) having a transadmittance of Y _m1 and a resistor (R), and a second TAA (62a) and a second TAA (62b) having a transadmittance of Y _m2 and Y _m3 , respectively. Element 62.

The first TAA 61a and the resistor R form the differentiator 61 by the same principle as the differentiator of FIGS. 4 and 5 described above. In addition, the current is fed back by the second TAA 52a and the third TAA 62b, where Y _m1 = Y _m2 = Y _m . Input impedance expressing the relationship between input voltage and output feedback current to be. In this equation of input impedance, s means frequency, and it can be seen from this equation that the input impedance changes with frequency.

The D value of the FDNR consisting of these three TAAs and the resistors is expressed by Equation (14).

7 to 13 are constituent circuit diagrams of an FDNR including a differentiator using an operational amplifier and a current feedback device using a TAA according to the present invention.

7 is a circuit diagram of a grounded FDNR according to a fourth embodiment of the present invention, wherein the differentiator 71 includes a voltage buffer 71a, a capacitor C, an operational amplifier 71b, and a resistor R. The current feedback element 72 is composed of a TAA 72a having a transadmittance Y _m .

The input voltage V _in transfers the input voltage as a unit gain through the voltage buffer 71a, and the capacitor C, the resistor R, and the operational amplifier 71b differentiate the transferred input voltage. The differential voltage of the operational amplifier 71b is input to generate an output feedback current. The relationship between the input voltage and the output feedback current can be expressed as input impedance, and this input impedance is to be. In this input impedance equation, s means frequency, and it can be seen from this equation that the impedance changes with frequency.

The D value of the FDNR according to FIG. 7 is expressed by Equation 15 below.

8 is a circuit diagram of a grounded FDNR according to a fifth embodiment of the present invention, in which the differentiator 81 includes an operational amplifier 81a, a voltage buffer 71b, a capacitor C, and resistors R, R1, and R2. ), And the current feedback element 82 is composed of a TAA 82a having a transadmittance Y _m .

The input voltage V _in is transmitted to the ends of the voltage dividers R1 and R2 by unit gain by the voltage buffer 81b, and is simultaneously generated by the non-inverting differentiator consisting of the operational amplifier, the capacitor C, and the resistor R. The differential voltage is transmitted to the other ends of the voltage dividers R1 and R2. The voltage dividers R1 and R2 divide the difference between the two voltages inputted at both ends by the ratio of the two resistors R1 and R2 and transfer the differential voltage to the current feedback element 82. The TAA 82a, the current feedback element 82, generates an output feedback current from the differential voltage. The input impedance representing the relationship between the input voltage and the output feedback current is to be. The input impedance of the FDNR according to FIG. 8 also varies with the frequency component s. The D value of this FDNR is expressed as in Equation (16).

Here, it is assumed that the resistance values of the two resistors R1 and R2 constituting the voltage divider are the same.

9 is a circuit diagram of a grounded FDNR according to a sixth embodiment of the present invention, in which the differentiator 91 includes an operational amplifier 91a, a voltage buffer 91b, a capacitor C, and a resistor R. The current feedback element 92 is composed of a TAA 92a having a transadmittance Y _m .

When the input voltage V _in is applied, the voltage buffer 91b buffers the input voltage with unit gain and transfers it to the positive input terminal of the TAA. In addition, the input voltage V _in is applied to the positive input (+) terminal of the operational amplifier 91a. The operational amplifier 91a, the capacitor C, and the resistor R are non-inverting differentials. Pass to the input (-) terminal. This TAA generates and outputs an output feedback current from the input voltage amplified by the differential voltage and the unit gain.

The relationship between this input voltage and the output feedback current can be expressed as input impedance, and this input impedance to be. This input impedance changes with the frequency s. The D value of the FDNR shown in FIG. 9 is expressed by Equation 17.

10 is a circuit diagram of a grounded FDNR according to a seventh embodiment of the present invention, in which the differentiator 101 includes a voltage buffer 101a, capacitors C1 and C2, a resistor R, an operational amplifier 101b, The voltage divider R1 and R2 are formed, and the current feedback element 102 is formed of the TAA 102a.

When the input voltage V _in is applied, the voltage buffer 101a buffers the input voltage in unit gain and differentiates it by the differential formed by the operational amplifier 101b through an impedance converter composed of resistors R and capacitors C1 and C2. Output voltage. The TAA 102a generates an output feedback current from the differential voltage of the operational amplifier 101b. Input impedance expressing the relationship between input voltage and output feedback current to be. It can be seen from this equation that the input impedance is changed by the frequency component.

The D value of the FDNR according to FIG. 10 is expressed by Equation 18 below.

Here, it is assumed that the resistance values of the two resistors R1 and R2 of the voltage divider are the same.

FIG. 11 is a circuit diagram of a grounded FDNR according to an eighth embodiment of the present invention, in which the differentiator 111 includes a voltage buffer 111a, a first operational amplifier 111b, a second operational amplifier 111c, and a capacitor. C) and resistors R, R1, R2, R3, and R4, and the current feedback element 112 is composed of a TAA 112a.

When the input voltage V _in is applied, the input voltage is buffered in unity gain through the voltage buffer 111a and transferred to the differential second operational amplifier 111c, and the capacitor C, the resistor R, and the first operational amplifier are supplied. It is delivered to the non-inverting differentiator consisting of 111b. This non-inverting differentiator generates a differential voltage and transfers it to the differential second operational amplifier 111c. The second operational amplifier 111c amplifies and outputs the difference voltage between the two voltages, and the output voltage of the second operational amplifier 111c is transmitted to the TAA 112a, which is the current feedback element 112, and the TAA 112a. Produces an output feedback current. The relationship between the input voltage and the output feedback current can be expressed as input impedance, and this input impedance is It can be seen that the input impedance is a value that varies with frequency.

The D value of the FDNR according to FIG. 11 is expressed by Equation 19.

Where R = R ₁ = R ₂ = R ₃ = R ₄ .

12 is a circuit diagram of a grounded FDNR according to a ninth embodiment of the present invention, in which the differentiator 121 includes an operational amplifier 121a, a capacitor C, and a resistor R, and a current feedback element 122. ) Consists of the TAA 122a.

The operational amplifier 121a, the capacitor C, and the resistor R form a non-inverting differentiator, and the voltage formed at the non-inverting differentiator is output by the TAA 122a as an output feedback current. The input voltage V _in is connected to the positive input (+) terminal of the operational amplifier 121a, and the connected input voltage is generated by the non-inverting differentiator composed of the operational amplifier. TAA 122a, which is a current feedback element, generates an output feedback current iout from this differential voltage. The relationship between the input voltage and the output feedback current can be expressed as input impedance, and this input impedance is to be. In the equation for the input impedance, s denotes the frequency component, and the input impedance changes with frequency.

The D value of the FDNR shown in FIG. 12 is expressed by Equation 20 below.

FIG. 13 is a circuit diagram of a grounded FDNR according to a tenth embodiment of the present invention, wherein the differentiator 131 includes a first operational amplifier 131a, a voltage divider R1 and R2, a second operational amplifier 131b, It consists of a capacitor (C) and a resistor (R), the current feedback element 132 is composed of a TAA (132a).

When the input voltage V _in is applied, the input voltage is transmitted to each of the non-inverting amplifier including the first operational amplifier 131a and the non-inverting differentiator including the second operational amplifier 131b. The first operational amplifier 131a amplifies and outputs the input voltage, and the non-inverting differentiator differentiates and outputs the input voltage. The TAA 132a, which is the current feedback element 132, generates and outputs an output feedback current from this differential voltage. The input impedance representing the relationship between this input voltage and the output feedback current to be. This input impedance is a value that varies with frequency components.

The D value of the FDNR shown in FIG. 13 is represented by Equations 21 and 22.

Here, R ₁ = R ₂ constituting the voltage divider.

Here, R ₁ ? R ₂ constituting the partial pressure divider.

14 is a configuration circuit diagram of the FDNR according to the eleventh embodiment. The differentiator 141 is composed of a TAA 141a having a transadmittance of Y _m and a resistor R, and the current feedback element 142 is composed of current transmitters CCI and CCII. When the input voltage V _in is applied, a differentiation is formed by the TAA 141a and the resistor R, and the differentiated voltage is input by the current transmitter 142a, which is output by the current transmitter 142a. The feedback current is generated and output. The relationship between this input voltage and the output feedback current can be expressed by the input impedance, and this input impedance to be. This input impedance is changed by the frequency component s.

The D value of the FDNR shown in FIG. 14 is expressed by Equation 23 below.

As described above, in the FDNR according to the present invention shown in the first to eleventh embodiments, the D value can be controlled by the direct current bias (or ratio of direct current bias) and the resistance (or ratio of resistance). have.

While the invention has been described above based on the preferred embodiments thereof, these embodiments are intended to illustrate rather than limit the invention. It will be apparent to those skilled in the art that various changes, modifications, or adjustments to the above embodiments can be made without departing from the spirit of the invention. Therefore, the protection scope of the present invention will be limited only by the appended claims, and should be construed as including all such changes, modifications or adjustments.

As described above, according to the present invention, by manufacturing the FDNR using the TAA and the operational amplifier, it is possible to simply configure the differential circuit and the frequency dependent circuit in various accounting systems. In addition, since the FDNR according to the present invention has a simple circuit configuration, it is advantageous to IC, and it is possible to easily and easily implement a measurement control system and medical electronic device, a filter, an oscillator, and the like including the same.

Claims (15)

Differential means including a transadmittance amplifier for generating and outputting a current according to an input voltage, and a resistance element for outputting a differential voltage according to the current output from the transadmittance amplifier; And a current feedback means composed of a transadmittance amplifier for generating and outputting an output feedback current according to the differential voltage generated by the differential means. The method of claim 1, The differential means includes a resistor connected between a first transadmittance amplifier to which a differential input voltage is applied and a differential output terminal of the first transadmittance amplifier, The current feedback means is characterized in that the input terminal comprises a second transmissive amplifier non-inverted connected to the differential output terminal of the first transadmittance amplifier and the output terminal is inverted connected to the differential input terminal of the first transadmittance amplifier. Floating frequency-dependent negative resistor. The method of claim 1, The differential means includes a first transadmittance amplifier to which a differential input voltage is applied, a transconductance amplifier having an input terminal connected to a differential output terminal of the first transadmittance amplifier, The current feedback means includes a second transmissive amplifier in which a differential input terminal is non-invertedly connected to the differential output terminal of the first transadmittance amplifier and the differential output terminal is invertedly connected to the differential input terminal of the first transadmittance amplifier. Floating type frequency-dependent negative resistor. The method of claim 1, The differential means includes a first transadmittance amplifier to which a differential input voltage is applied, and a resistor connected between a single output terminal of the first transadmittance amplifier and ground; The current feedback means includes a second transadmittance amplifier in which a differential input terminal is invertedly connected to both ends of the resistor, a single output terminal is connected to a positive input terminal of the first transadmittance amplifier, and a differential input terminal is inferior to both ends of the resistance. And a third transadmittance amplifier inverted and having a single output terminal connected to a sub-input terminal of the first transadmittance amplifier. A differential buffer including a voltage buffer buffered at an input voltage at a unit gain and transmitted to a rear stage, and an operational amplifier generating and outputting a differential voltage according to the input voltage; And a transadmittance amplifier which is a current feedback device for generating and outputting an output feedback current according to the differential voltage generated by the differential means. The method of claim 5, wherein the differential means, A voltage buffer for buffering and outputting a single input voltage in unit gain, a capacitor connected to one end of the output of the voltage buffer to filter the AC component of the buffered single input voltage, and the other end of the capacitor connected to the negative input terminal The input terminal is grounded, and the output terminal includes an operational amplifier connected to the positive input terminal of the transadmittance amplifier, and a grounding type frequency-dependent negative, characterized in that the feedback resistor is connected between the negative input terminal and the output terminal of the operational amplifier. resistor. The method of claim 5, wherein the differential means, An operational amplifier in which a single input voltage is applied to the positive input terminal, a capacitor connected between the negative input terminal of the operational amplifier and ground, a feedback resistor connected between the negative input terminal and the output terminal of the operational amplifier, and the single input voltage A voltage buffer for buffering and outputting a unit gain, and a differential voltage proportional to a voltage difference between an output voltage of the operational amplifier and an input voltage connected between an output terminal of the operational amplifier and an output terminal of the voltage buffer; Ground-type frequency-dependent negative resistor, characterized in that it comprises a voltage divider provided to the negative input terminal of the. The method of claim 5, wherein the differential means, A single input voltage is applied to the positive input terminal and an output amplifier of which the output terminal is connected to the negative input terminal of the transadmittance amplifier, a capacitor connected between the negative input terminal of the operational amplifier and ground, the negative input terminal and the output terminal of the operational amplifier And a voltage buffer connected between the feedback resistor and the single input voltage in unit gain to provide a positive input to the positive input terminal of the transadmittance amplifier. The method of claim 5, wherein the differential means, A voltage buffer for buffering and outputting a single input voltage in unit gain, a capacitor and a first resistor sequentially connected between the output terminal of the voltage buffer and the ground, a common contact of the capacitor and the resistor, and a positive input terminal are connected, and the output terminal is An operational amplifier connected to the negative input terminal of the transadmittance amplifier, a second resistor connected between the negative input terminal of the operational amplifier and ground, a third resistor connected between the output terminal and the negative input terminal of the operational amplifier, and the operational amplifier A ground-type frequency-dependent negative resistor, characterized in that it comprises a capacitor connected between the output terminal and the positive input terminal. The method of claim 5, wherein the differential means, A first operational amplifier to which a single input voltage is applied to a positive input terminal, a capacitor connected between the negative input terminal of the first operational amplifier and ground, and a feedback resistor connected between the negative input terminal and the output terminal of the first operational amplifier And a voltage buffer for buffering and outputting the single input voltage as a unit gain, a voltage divider connected between an output terminal of the voltage buffer and a ground, and a voltage distributed from the voltage divider to a positive input terminal, and an output terminal receiving the transadmittance amplifier. A second operational amplifier connected to the sub-input terminal of the resistor; a resistance connected between the output terminal of the first operational amplifier and the sub-input terminal of the second operational amplifier; A grounded frequency-dependent negative resistor comprising a resistor connected between terminals. Differential means including an operational amplifier for generating and outputting a differential voltage according to an input voltage; Ground type frequency-dependent, characterized in that it comprises a transadmittance amplifier which is a current feedback element for receiving the differential voltage generated by the differential means to the negative input terminal to generate an output feedback current and to feed back the output feedback current to the positive input terminal. Negative resistor. The method of claim 11, wherein the differential means, A single input voltage is applied to the positive input terminal, an output amplifier connected to the negative input terminal of the transadmittance amplifier, one end connected to the negative input terminal of the operational amplifier, the other end is a grounded capacitor, the negative input terminal of the operational amplifier And a feedback resistor connected between the output terminal and the output terminal. The method of claim 12, wherein the differential means, And a non-inverting amplifier connected between the single input voltage and the other end of the capacitor and ground. The method of claim 13, wherein the non-inverting amplifier, An amplification operational amplifier in which the single input voltage is applied to the positive input terminal and connected to an output terminal and the other end of the capacitor; A ground type frequency-dependent negative resistor comprising a resistor connected between an input terminal and an output terminal of the amplification operational amplifier. Differential means including an operational amplifier for generating and outputting a differential voltage according to an input voltage; And a current transmitter which is a current feedback element for generating and outputting an output feedback current according to the differential voltage generated by the differential means.