阅读说明：本技术 一种电感电容检测电路 (Inductance and capacitance detection circuit ) 是由 邹亮 于 2019-11-12 设计创作，主要内容包括：本发明公开了一种电感电容检测电路,包括：信号发生器、待测元件、AB运算放大器、输出级、电阻R2和滤波器；待测元件一端与信号发生器相连,另一端连接AB运算放大器的输入端,运算放大器的输出端与输出级相连,输出级通过电流叠加电路与滤波器相连,电流叠加电路通过电阻R2接地。本发明电路简单,操作方便,采用同一电路,通过更换待测电容与电感,既能实现电容值得检测,也能实现电感值的检测。(The invention discloses an inductance-capacitance detection circuit, which comprises: the device comprises a signal generator, an element to be tested, an AB operational amplifier, an output stage, a resistor R2 and a filter; one end of the element to be tested is connected with the signal generator, the other end of the element to be tested is connected with the input end of the AB operational amplifier, the output end of the operational amplifier is connected with the output stage, the output stage is connected with the filter through the current superposition circuit, and the current superposition circuit is grounded through the resistor R2. The circuit is simple, the operation is convenient, the same circuit is adopted, and the capacitance value detection and the inductance value detection can be realized by replacing the capacitor to be detected and the inductor to be detected.)

1. An inductance capacitance detection circuit, comprising: the device comprises a signal generator, an element to be tested, an AB operational amplifier, an output stage, a resistor R2 and a filter; one end of the element to be tested is connected with the signal generator, the other end of the element to be tested is connected with the input end of the AB operational amplifier, the output end of the operational amplifier is connected with the output stage, the output stage is connected with the filter through the current superposition circuit, and the current superposition circuit is grounded through the resistor R2.

2. The LC detection circuit of claim 1, wherein said output stage comprises MOS transistor Q1 and MOS transistor Q2, and said AB operational amplifiers are respectively connected to the input terminals of MOS transistor Q1 and MOS transistor Q2; the output end of the MOS transistor Q1 and the output end of the MOS transistor Q2 are connected with the filter after passing through the current superposition circuit.

3. The LC detection circuit as claimed in claim 2, wherein the output terminal of the operational amplifier is connected to the gates of the MOS transistor Q1 and the MOS transistor Q2, respectively, the drains of the MOS transistor Q1 and the MOS transistor Q2 are connected to the DUT, and the sources of the MOS transistor Q1 and the MOS transistor Q2 are connected to the current superposition circuit.

4. The LC detection circuit of claim 3, wherein the current superposition circuit comprises MOS transistor Q3, MOS transistor Q4, MOS transistor Q5 and MOS transistor Q6; the gates of the MOS transistor Q3 and the MOS transistor Q6 are connected with the output end of the AB operational amplifier; the grid electrode of the MOS transistor Q1 is respectively connected with the source electrodes of the MOS transistor Q3, the MOS transistor Q4 and the MOS transistor Q5; the MOS transistor Q4 is connected with the grid electrode of the MOS transistor Q5 and is connected with the source electrode of the MOS transistor Q6, and the source electrode of the MOS transistor Q6 is also connected with the drain electrode of the MOS transistor Q4; the drains of the MOS transistor Q3 and the MOS transistor Q5 are connected to one end of the resistor R2, and the drain of the MOS transistor Q6 is connected to the other end of the resistor R2.

5. The LC detection circuit of claim 1, wherein a resistor R1 is connected between said DUT and said signal generator.

6. The LC detection circuit of claim 1 or 5, wherein the DUT comprises an unknown capacitance Cx or an unknown inductance Lx.

7. The LC detection circuit of claim 1, wherein the filter comprises a resistor R3 and a capacitor C1 connected in parallel.

Technical Field

The invention belongs to the technical field of electronic parameter detection, and particularly relates to an inductance-capacitance detection circuit.

Background

Accurate measurement of inductance and capacitance values of electronic components and parts of electronic equipment is a basic parameter detection work. The existing capacitor detection generally adopts constant current to charge a capacitor, and detects the detected capacitor by detecting the voltage at two ends of the capacitor; inductance sensing typically employs a constant voltage applied to an inductance, which is sensed by sensing the current through the inductance. The capacitance detection and the inductance detection adopt different circuits, and the same circuit cannot detect both the capacitance and the inductance.

Therefore, how to provide an inductance-capacitance detection circuit is a problem that needs to be solved by those skilled in the art.

Disclosure of Invention

In view of this, the invention provides an inductor-capacitor detection circuit, which is simple in circuit and convenient to operate, and by using the same circuit and replacing a capacitor to be detected and an inductor, the detection of a capacitance value and the detection of an inductance value can be realized.

In order to achieve the purpose, the invention adopts the following technical scheme:

an inductance capacitance detection circuit comprising: the device comprises a signal generator, an element to be tested, an AB operational amplifier, an output stage, a resistor R2 and a filter; one end of the element to be tested is connected with the signal generator, the other end of the element to be tested is connected with the input end of the AB operational amplifier, the output end of the operational amplifier is connected with the output stage, the output stage is connected with the filter through the current superposition circuit, and the current superposition circuit is grounded through the resistor R2.

Preferably, the output stage comprises a MOS transistor Q1 and a MOS transistor Q2, and the AB operational amplifiers are respectively connected with the input ends of the MOS transistor Q1 and the MOS transistor Q2; the output end of the MOS transistor Q1 and the output end of the MOS transistor Q2 are connected with the filter after passing through the current superposition circuit.

Preferably, the output end of the operational amplifier is respectively connected with the gates of the MOS transistor Q1 and the MOS transistor Q2, the drains of the MOS transistor Q1 and the MOS transistor Q2 are connected with the element to be tested, and the sources of the MOS transistor Q1 and the MOS transistor Q2 are connected with the current superposition circuit.

Preferably, the current superposition circuit comprises a MOS transistor Q3, a MOS transistor Q4, a MOS transistor Q5 and a MOS transistor Q6; the gates of the MOS transistor Q3 and the MOS transistor Q6 are connected with the output end of the AB operational amplifier; the grid electrode of the MOS transistor Q1 is respectively connected with the source electrodes of the MOS transistor Q3, the MOS transistor Q4 and the MOS transistor Q5; the MOS transistor Q4 is connected with the grid electrode of the MOS transistor Q5 and is connected with the source electrode of the MOS transistor Q6, and the source electrode of the MOS transistor Q6 is also connected with the drain electrode of the MOS transistor Q4; the drains of the MOS transistor Q3 and the MOS transistor Q5 are connected to one end of the resistor R2, and the drain of the MOS transistor Q6 is connected to the other end of the resistor R2.

Preferably, a resistor R1 is connected between the element to be measured and the signal generator.

Preferably, the element to be measured includes an unknown capacitance Cx or an unknown inductance Lx.

Preferably, the filter comprises a resistor R3 and a capacitor C1 connected in parallel.

The invention has the beneficial effects that:

the circuit is simple, the current of the element to be tested flows out of the output stage of the AB operational amplifier, the current of the output stage is detected, the current superposition is carried out through the current superposition circuit, the current is converted into voltage through the resistor R2, and finally the voltage is filtered through the filter, so that the direct current output voltage can be obtained, and the value of the element to be tested is obtained. The invention adopts the same circuit, only needs to replace the capacitor to be detected and the inductor, can realize the detection of the capacitance value and the inductance value, and has convenient operation.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

FIG. 1 is a circuit diagram of a detection capacitor according to the present invention.

Fig. 2 is a circuit diagram of the detecting inductor according to the present invention.

FIG. 3 is another circuit diagram of the detection capacitor of the present invention.

Fig. 4 is another circuit diagram of the detection inductor of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1-2, the present invention provides an inductance-capacitance detecting circuit, including: the device comprises a signal generator, an element to be tested, an AB operational amplifier, an output stage, a resistor R2 and a filter; one end of the element to be tested is connected with the signal generator, the other end of the element to be tested is connected with the negative pin of the input end of the AB operational amplifier, the positive pin of the operational amplifier is connected with the working voltage Vdd/2, the output end of the operational amplifier is connected with the output stage, the output stage is connected with the filter through the current superposition circuit, and the current superposition circuit is grounded through the resistor R2. The element to be measured includes an unknown capacitance Cx or an unknown inductance Lx. The invention adopts the same circuit, only needs to replace the capacitor to be detected and the inductor, can realize the detection of the capacitance value and the inductance value, and has convenient operation.

The output stage comprises an MOS tube Q1 and an MOS tube Q2, and the AB operational amplifier is respectively connected with the input end of an MOS tube Q2 of an MOS tube Q1; the output end of the MOS transistor Q1 and the output end of the MOS transistor Q2 are connected with the filter after passing through the current superposition circuit.

The output end of the operational amplifier is respectively connected with the grids of the MOS tube Q1 and the MOS tube Q2, the drains of the MOS tube Q1 and the MOS tube Q2 are connected with an element to be tested, and the sources of the MOS tube Q1 and the MOS tube Q2 are connected with a current superposition circuit. The source of the MOS transistor Q1 is connected to its operating voltage Vdd.

Referring to fig. 3-4, the current superposition circuit includes a MOS transistor Q3, a MOS transistor Q4, a MOS transistor Q5, and a MOS transistor Q6; the gates of the MOS transistor Q3 and the MOS transistor Q6 are connected with the output end of the AB operational amplifier; the grid electrode of the MOS transistor Q1 is respectively connected with the source electrodes of the MOS transistor Q3, the MOS transistor Q4 and the MOS transistor Q5; the MOS transistor Q4 is connected with the grid electrode of the MOS transistor Q5 and is connected with the source electrode of the MOS transistor Q6, and the source electrode of the MOS transistor Q6 is also connected with the drain electrode of the MOS transistor Q4; the drains of the MOS transistor Q3 and the MOS transistor Q5 are connected and connected with one end of the resistor R2, and the drain of the MOS transistor Q6 is connected with the other end of the resistor R2.

In order to further optimize the technical scheme, a resistor R1 is connected between the element to be tested and the signal generator.

In order to further optimize the above technical solution, the filter includes a resistor R3 and a capacitor C1 connected in parallel.

The circuit is simple, the current of the element to be tested flows out of the output stage of the AB operational amplifier, the current of the output stage is detected, the current superposition is carried out through the current superposition circuit, the current is converted into voltage through the resistor R2, and finally the voltage is filtered through the filter, so that the direct current output voltage can be obtained, and the value of the element to be tested is obtained. The invention adopts the same circuit, only needs to replace the capacitor to be detected and the inductor, can realize the detection of the capacitance value and the inductance value, and has convenient operation.

The working principle of the invention is as follows:

the input signal of the signal generator is a sine wave with frequency omega and amplitude A, the AB operational amplifier can lock the voltage of the negative input end of the AB operational amplifier, the current of the unknown capacitor Cx or the unknown inductor Lx can all flow out of the output stage of the AB operational amplifier, the current of the output stage is detected and added, the current is converted into voltage through a resistor R2, and then the voltage is filtered through a filter, so that the direct-current output voltage can be obtained. And calculating to obtain the inductance or the current value through the output voltage. The final output voltage is Vout, and the average current detected is Iavg-Vout/R2.

Because the quiescent current of the output stage affects the accuracy of current detection, the quiescent current of the output stage can be designed to be much smaller than the current peak value flowing through the inductance and capacitance, so that the error contribution of the quiescent current to the current detection circuit can be ignored. For example, if the detected average current is Iavg and the output stage quiescent current is Ista, the actual average current is Iavg + Ista.

In addition, when detecting the inductor Lx, a detection error may be caused by a static dc current flowing through the inductor Lx, and may be eliminated by adjusting the offset voltage of the input signal (adding a dc voltage, increasing or decreasing until the current flowing from this voltage becomes 0).

Through calculation, the capacitance value or the current value can be obtained as

The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. The device disclosed by the embodiment corresponds to the method disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the method part for description.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.