An automatic gain control circuit for resistivity logging

Abstract

The application discloses a kind of resistivity logging automatic gain control circuit, comprising: transconductance amplifier circuit, signal conditioning circuit, integration circuit, the transconductance amplifier circuit includes: transconductance amplifier, resistance R1, resistance R2, resistance R3, the one end of resistance R1 is connected with the noninverting terminal of transconductance amplifier, the other end of resistance R1 is grounded, the one end of resistance R2 is connected with the inverting terminal of transconductance amplifier, the other end of resistance R2 is grounded, the one end of resistance R3 is connected with the inverting terminal of transconductance amplifier, the other end of resistance R3 is connected with the output terminal of transconductance amplifier, output voltage V2 is input into signal conditioning circuit, and the signal of control foot CON is given by integration circuit.The resistivity logging automatic gain control circuit of the application, this control circuit can automatically adjust amplification according to the amplitude of input signal, also has the characteristics of strong anti-interference ability, good stability, easy debugging, etc., is suitable for the characteristics of downhole high temperature, complex environment etc.

Description

Technical Field

[0001] The present invention relates to the field of electronic technology, in particular to a resistivity logging automatic gain control circuit. Background Art

[0002] Resistivity logging is a method of measuring rock resistivity using power supply electrodes and measuring electrodes arranged at different locations in a borehole. The three commonly used resistivity logging series are deep lateral, shallow lateral, and microlateral resistivity logging. With the development of resistivity logging technology, a reliable signal processing system is needed to ensure stable and efficient operation of the equipment. Due to the complex downhole temperature, humidity, and vibration environment, the signal amplitude will vary greatly. Therefore, a control circuit with strong anti-interference ability, good stability, and easy debugging is needed, which is suitable for the high temperature and complex environment of downhole.

[0003] Therefore, it is necessary to propose a resistivity logging automatic gain control circuit to solve the above problems. Summary of the Invention

[0004] The main purpose of the present invention is to provide a resistivity logging automatic gain control circuit, which can effectively solve the problems in the background technology.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] A resistivity logging automatic gain control circuit includes: a transconductance amplifier circuit, a signal conditioning circuit, and an integration circuit. The transconductance amplifier circuit includes: a transconductance amplifier, a resistor R1, a resistor R2, and a resistor R3. One end of the resistor R1 is connected to the non-inverting terminal of the transconductance amplifier, and the other end of the resistor R1 is grounded. One end of the resistor R2 is connected to the inverting terminal of the transconductance amplifier, and the other end of the resistor R2 is grounded. One end of the resistor R3 is connected to the inverting terminal of the transconductance amplifier, and the other end of the resistor R3 is connected to the output terminal of the transconductance amplifier. A signal V2 output by the transconductance amplifier is input into the signal conditioning circuit, and a signal of a control pin CON is output by the integration circuit.

[0007] Preferably, the signal conditioning circuit includes an operational amplifier, a resistor R4, a resistor R5, a resistor R6, a resistor R7, and a resistor R8, one end of the resistor R4 is connected to the in-phase terminal of the operational amplifier, the other end of the resistor R4 is grounded, and one end of the resistor R5 is connected to the input signal V2.

[0008] Preferably, the other end of the resistor R5 is connected to the inverting end of the operational amplifier, one end of the resistor R6 is connected to the inverting end of the operational amplifier, and the other end of the resistor R6 is connected to the output end of the operational amplifier.

[0009] Preferably, one end of the resistor R7 is connected to the output end of the operational amplifier, the other end of the resistor R7 is connected to the anode of the diode D1, one end of the resistor R8 is connected to the input signal V2, the other end of the resistor R8 is connected to the anode of the diode D2, the cathodes of the diode D1 and the diode D2 are connected in parallel to output the signal V3, and the signal V3 is input into the integration circuit.

[0010] Preferably, the integration circuit includes: an operational amplifier, a resistor R9, a resistor R10, a resistor R11, a capacitor C1, and a capacitor C2, one end of the resistor R9 is connected to the output signal V3 of the signal conditioning circuit; the non-inverting end of the operational amplifier is grounded, and the inverting end of the operational amplifier receives the signal V3.

[0011] Preferably, the other end of the resistor R9 is connected to the resistor R10, one end of the resistor R10 is connected to the output end of the operational amplifier, and the other end of the resistor R10 is connected to the resistor R9.

[0012] Preferably, the capacitor C1 is connected in parallel with the resistor R9, the capacitor C2 is connected in parallel with the resistor R10, one end of the resistor R11 is connected to the output end of the operational amplifier, and the other end of the resistor R11 is connected to the control pin CON of the transconductance amplifier.

[0013] Preferably, the values ​​of the capacitor C1 and the capacitor C2 are between 47nF and 100nF, and the value of the resistor R1 is between 20kΩ and 47kΩ.

[0014] Beneficial effects

[0015] Compared with the prior art, the present invention provides a resistivity logging automatic gain control circuit with the following beneficial effects:

[0016] 1. This resistivity logging automatic gain control circuit can automatically adjust the amplification factor according to the amplitude of the input signal, so that when the input signal is small, the output signal is large, and when the input signal is large, the output signal is small. The resistivity logging automatic gain control circuit also has the characteristics of strong anti-interference ability, good stability, and easy debugging. It is suitable for high temperature and complex environment downhole. The resistivity logging automatic gain control circuit requires a wide range and flexible gain adjustment capability. This automatic gain control circuit has a wide adjustment range, excellent anti-interference ability, and higher stability.

[0017] 2. The resistivity logging automatic gain control circuit is connected to the inverting terminal of the transconductance amplifier U1 through one end of the resistor R3, and the other end is connected to the output terminal of the transconductance amplifier U1, which can be used for negative feedback. It is connected to the non-inverting terminal of the operational amplifier U2 through one end of the resistor R4, and the other end is grounded, which can be used to balance impedance. It is connected to the input signal V2 through one end of the resistor R5, and the other end is connected to the inverting terminal of the operational amplifier U2, which can be used to set the amplification factor. It is connected to the inverting terminal of the operational amplifier U2 through one end of the resistor R6, and the other end is connected to the output terminal of the operational amplifier U2, which can be used for negative feedback. It is connected to the output terminal of the operational amplifier U2 through one end of the resistor R7, and the other end is connected to the anode of the diode D1, which can be used to control the output current. It is connected to the input signal V2 through one end of the resistor R8, and the other end is connected to the anode of the diode D2, which can be used to control the output current.

[0018] 3. The resistivity logging automatic gain control circuit is connected to the output signal V3 of the signal conditioning circuit through one end of the resistor R9 and the other end is connected to the resistor R10, which can be used to release the voltage on the capacitor C1. One end of the resistor R10 is connected to the output end of the operational amplifier U3 and the other end is connected to the resistor R9, which can be used to release the voltage on the capacitor C2. The capacitor C1 and the resistor R9 are connected in parallel, which can be used to store charge. The capacitor C2 and the resistor R10 are connected in parallel, which can be used to store charge. One end of the resistor R11 is connected to the output end of the operational amplifier U3 and the other end is connected to the output signal CON, which can be used to set the current. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural diagram of the control circuit of the present invention;

[0020] Figure 2 is a circuit diagram of a transconductance amplifier circuit of the present invention;

[0021] Figure 3 is a circuit diagram of a signal conditioning circuit of the present invention;

[0022] Figure 4 1 is a circuit diagram of an integrating circuit of the present invention.

[0023] In the figure: 101, transconductance amplifier circuit; 102, signal conditioning circuit; 103, integration circuit. DETAILED DESCRIPTION

[0024] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below in conjunction with specific implementation methods.

[0025] like Figure 1-4As shown, a resistivity logging automatic gain control circuit includes: a transconductance amplifier circuit 101, a signal conditioning circuit 102, and an integration circuit 103. The transconductance amplifier circuit 101 includes: a transconductance amplifier U1, a resistor R1, a resistor R2, and a resistor R3. One end of the resistor R1 is connected to the non-inverting terminal of the transconductance amplifier U1, and the other end of the resistor R1 is grounded. One end of the resistor R2 is connected to the inverting terminal of the transconductance amplifier U1, and the other end of the resistor R2 is grounded. One end of the resistor R3 is connected to the inverting terminal of the transconductance amplifier U1, and the other end of the resistor R3 is connected to the output terminal of the transconductance amplifier U1. The output signal V2 of U1 is input to the signal conditioning circuit 102, and the signal of the control pin CON is given by the integration circuit 103. The signal conditioning circuit 102 includes an operational amplifier U2, a resistor R4, a resistor R5, a resistor R6, a resistor R7, and a resistor R8. One end of the resistor R4 is connected to the non-inverting terminal of the operational amplifier U2, and the other end of the resistor R4 is grounded. One end of the resistor R5 is connected to the input signal V2, and the other end of the resistor R5 is connected to the inverting terminal of the operational amplifier U2. One end of the resistor R6 is connected to the inverting terminal of the operational amplifier U2, and the other end of the resistor R6 is connected to the input terminal of the operational amplifier U2. The output terminal of the operational amplifier U2 is connected to one end of the resistor R7, the other end of the resistor R7 is connected to the anode of the diode D1, one end of the resistor R8 is connected to the input signal V2, the other end of the resistor R8 is connected to the anode of the diode D2, the cathodes of the diode D1 and the diode D2 are connected in parallel to output the signal V3, and the signal V3 is input to the integration circuit 103, which includes: an operational amplifier U3, a resistor R9, a resistor R10, a resistor R11, a capacitor C1, and a capacitor C2. The non-inverting terminal of the operational amplifier U3 is grounded, and the inverting terminal of the operational amplifier U3 receives the signal V3. One end of resistor R9 is connected to the output signal V3 of the signal conditioning circuit 102, the other end of resistor R9 is connected to resistor R10, one end of resistor R10 is connected to the output end of the operational amplifier U3, the other end of resistor R10 is connected to resistor R9, capacitor C1 is connected in parallel with resistor R9, capacitor C2 is connected in parallel with resistor R10, one end of resistor R11 is connected to the output end of the operational amplifier U3, the other end of resistor R11 is connected to the control pin CON of the transconductance amplifier, the values ​​of capacitors C1 and C2 are between 47nF and 100nF, and the value of resistor R1 is between 20kΩ and 47kΩ.

[0026] This control circuit can automatically adjust the amplification factor according to the amplitude of the input signal, so that when the input signal is small, the output signal is large, and when the input signal is large, the output signal is small. The resistivity logging automatic gain control circuit also has the characteristics of strong anti-interference ability, good stability, and easy debugging. It is suitable for high temperature and complex environment underground. The resistivity logging automatic gain control circuit requires a wide range and flexible gain adjustment capability. This automatic gain control circuit has a wide adjustment range, excellent anti-interference ability, and higher stability. One end of the resistor R3 is connected to the inverting end of the transconductance amplifier U1, and the other end is connected to the output end of the transconductance amplifier U1, which can be used for negative feedback. One end of the resistor R4 is connected to the non-inverting end of the operational amplifier U2, and the other end is grounded, which can be used to balance impedance. One end of the resistor R5 is connected to the input signal V2, and the other end is connected to the inverting end of the operational amplifier U2, which can be used to set the amplification factor. One end of the resistor R6 is connected to the operational The inverting end of the operational amplifier U2 and the other end are connected to the output end of the operational amplifier U2, which can be used for negative feedback. One end of the resistor R7 is connected to the output end of the operational amplifier U2, and the other end is connected to the anode of the diode D1, which can be used to control the output current. One end of the resistor R8 is connected to the input signal V2, and the other end is connected to the anode of the diode D2, which can be used to control the output current. One end of the resistor R9 is connected to the output signal V3 of the signal conditioning circuit 102, and the other end is connected to the resistor R10, which can be used to release the voltage on the capacitor C1. One end of the resistor R10 is connected to the output end of the operational amplifier U3, and the other end is connected to the resistor R9, which can be used to release the voltage on the capacitor C2. The capacitor C1 is connected in parallel with the resistor R9, which can be used to store charge. The capacitor C2 is connected in parallel with the resistor R10, which can be used to store charge. One end of the resistor R11 is connected to the output end of the operational amplifier U3, and the other end outputs the signal V_CON, which can be used to set the current. Specific embodiment one:

[0028] like Figure 1The above is a structural diagram of a resistivity logging automatic gain control circuit in this patent, which includes: a transconductance amplifier circuit 101: its function is to design the basic amplification factor and adjust the amplification factor by the current flowing into the control pin CON, a signal conditioning circuit 102: its function is to shape the AC signal output by the transconductance amplifier circuit 101, an integration circuit 103: its function is to convert the rectified voltage value output by the signal conditioning circuit 102 into a DC voltage value and input it into the control pin CON of the transconductance amplifier circuit 101. This resistivity logging automatic gain control circuit adopts the basic principle of negative feedback. When the input signal V1 increases, the output signal V2 of the transconductance amplifier circuit 101 also increases, the output signal V3 of the signal conditioning circuit 102 decreases, and the output V_CON of the integration circuit 103 also increases. At this time, the current flowing into the control pin CON of the transconductance amplifier circuit 101 decreases, causing the output signal V2 of the transconductance amplifier circuit 101 to also decrease. In this way, negative feedback is formed, so that a larger amplification factor can be obtained when a small signal is input, and a smaller amplification factor can be obtained when a large signal is input. Specific embodiment two:

[0030] like Figure 2 As described above, for the transconductance amplifier circuit 101 in the embodiment of the present application, the maximum gain value can be set by setting the resistance value parameters of the resistors R1 and R2, and the gain value can be reduced by controlling the current value flowing into the control pin CON. Specific embodiment three:

[0032] like Figure 3 The above is the signal conditioning circuit 102 in the embodiment of the present application, which reverses V2 through an operational amplifier and takes V2 at the same time, and performs full-wave rectification on these two signals through D1 and D2 and enters the integration circuit. Specific embodiment four:

[0034] like Figure 4 The above is the integration circuit 103 in the embodiment of the present application. The V3 signal is integrated by the operational amplifier to obtain a DC voltage. The specific DC voltage can be set by setting the capacitance values ​​of capacitors C1 and C2. The current of the control pin CON of the input transconductance amplifier circuit 101 can be adjusted by setting the resistance value of resistor R11.

[0035] An automatic gain control circuit for resistivity logging in the embodiment of this patent was designed, manufactured, debugged and experimentally tested. The experimental results show that the circuit can automatically adjust the gain between 3-2 times when the input signal is 0.5V-1.5V.

[0036] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A resistivity logging automatic gain control circuit, comprising: A transconductance amplifier circuit (101), a signal conditioning circuit (102), and an integration circuit (103), characterized in that: the transconductance amplifier circuit (101) comprises: a transconductance amplifier U1, a resistor R1, a resistor R2, and a resistor R3, one end of the resistor R1 is connected to the non-inverting end of the transconductance amplifier U1, the other end of the resistor R1 is grounded, one end of the resistor R2 is connected to the inverting end of the transconductance amplifier U1, the other end of the resistor R2 is grounded, one end of the resistor R3 is connected to the inverting end of the transconductance amplifier U1, the other end of the resistor R3 is connected to the output end of the transconductance amplifier U1, a signal V2 output by the transconductance amplifier U1 is input into the signal conditioning circuit (102), and a signal of the control pin CON is given by the integration circuit (103); The signal conditioning circuit includes an operational amplifier U2, a resistor R4, a resistor R5, a resistor R6, a resistor R7, and a resistor R8, wherein one end of the resistor R4 is connected to the non-inverting terminal of the operational amplifier U2, the other end of the resistor R4 is grounded, and one end of the resistor R5 is connected to the input signal V2; the other end of the resistor R5 is connected to the inverting terminal of the operational amplifier U2, one end of the resistor R6 is connected to the inverting terminal of the operational amplifier U2, and the other end of the resistor R6 is connected to the output terminal of the operational amplifier U2; one end of the resistor R7 is connected to the output terminal of the operational amplifier U2, the other end of the resistor R7 is connected to the anode of the diode D1, one end of the resistor R8 is connected to the input signal V2, and the other end of the resistor R8 is connected to the anode of the diode D2, the cathodes of the diode D1 and the diode D2 are connected in parallel to output a signal V3, and the signal V3 is input into the integration circuit (103); The integration circuit comprises: an operational amplifier U3, a resistor R9, a resistor R10, a resistor R11, a capacitor C1, and a capacitor C2, wherein one end of the resistor R9 is connected to the output signal V3 of the signal conditioning circuit (102); the non-inverting end of the operational amplifier U3 is grounded, and the inverting end of the operational amplifier U3 receives the signal V3; the other end of the resistor R9 is connected to the resistor R10, one end of the resistor R10 is connected to the output end of the operational amplifier U3, and the other end of the resistor R10 is connected to the resistor R9; the capacitor C1 is connected in parallel to the resistor R9, the capacitor C2 is connected in parallel to the resistor R10, one end of the resistor R11 is connected to the output end of the operational amplifier U3, and the other end of the resistor R11 is connected to the control pin CON of the transconductance amplifier U1.

2. The resistivity logging automatic gain control circuit according to claim 1, characterized in that: The values ​​of the capacitor C1 and the capacitor C2 are between 47nF and 100nF, and the value of the resistor R1 is between 20kΩ and 47kΩ.

Images