CN220570675U

CN220570675U - Load resistance detection circuit and power amplifier testing device

Info

Publication number: CN220570675U
Application number: CN202322054272.7U
Authority: CN
Inventors: 王恒; 曾维坚; 张金开; 伍巨猷; 陈文就
Original assignee: Guangzhou DSPPA Audio Co Ltd
Current assignee: Guangzhou DSPPA Audio Co Ltd
Priority date: 2023-08-01
Filing date: 2023-08-01
Publication date: 2024-03-08
Anticipated expiration: 2033-08-01

Abstract

The application provides a load resistance detection circuit and power amplifier testing arrangement, under the circumstances of device output power amplifier signal that awaits measuring, relay control module switches on the connection between the coil of relay and the power amplifier ground, and the coil gets the electricity, and the normally open contact of relay is connected to the movable contact of relay for the device that awaits measuring can connect load resistance, in order to accomplish the test of device that awaits measuring. Under the condition that the device to be tested does not output a power amplification signal, the relay control module breaks the connection between the coil and the power amplification ground, the coil loses electricity, the movable contact of the relay is connected with the normally-closed contact of the relay, and the first working power supply, the load resistor, the current detection module and the power supply form a loop, so that the current detection module can detect the resistance current value of the load resistor and output a detection signal. The control module can determine the actual resistance value of the load resistor according to the detection signal. By adopting the scheme of the application, the test efficiency and the accuracy of the test result can be considered.

Description

Load resistance detection circuit and power amplifier testing device

Technical Field

The application relates to the technical field of electronic circuits, in particular to a load resistance detection circuit and a power amplifier testing device.

Background

When the power amplifier output of the whole audio equipment or the power amplifier output of the semi-finished circuit board are tested, the load resistor with the corresponding resistance value is connected to the power amplifier output end of the audio equipment or the semi-finished circuit board according to the requirement of the operation guiding parameter, and the working parameter of the whole audio equipment or the semi-finished circuit board under the corresponding load resistor is obtained, so that the test is finished. Therefore, the resistance value of the load resistor influences the test result of the power amplifier test.

However, during the power amplifier test, the load resistor is not connected to the output end of the power amplifier, the load resistor with an incorrect resistance value is connected, the actual resistance value of the load resistor is not consistent with the nominal resistance value, or the resistor is damaged, and the like may occur. However, the existing test circuit cannot timely determine whether the resistance value of the load resistor meets the requirement of the operation guidance parameter. When the load resistor is problematic, a tester cannot timely learn the situation and replace the load resistor. Therefore, whenever a problem occurs in the load resistor, the tester needs to spend a lot of time to retest each audio device or the semi-finished circuit board, reducing the test efficiency, or the problem of the load resistor cannot be found, resulting in unreliable test results.

Disclosure of Invention

The object of the present application is to solve at least one of the above-mentioned technical drawbacks, in particular the technical drawbacks of the prior art in which the test results are not reliable.

In a first aspect, an embodiment of the present application provides a load resistance detection circuit, including:

the coil and the normally-closed contact of the relay are both used for being connected with a first working power supply, the normally-open contact of the relay is used for being connected with the power amplifier output end of the device to be tested, and the movable contact of the relay is used for being connected with the first end of the load resistor;

the relay control module is connected with the coil and is used for being respectively connected with the power amplifier output end and the power amplifier ground; the relay control module is used for conducting connection between the coil and the power amplification ground when the power amplification signal output by the device to be detected is detected, and disconnecting the coil and the power amplification ground when the power amplification signal output by the device to be detected is not detected;

the first input end of the current detection module is used for being connected with the second end of the load resistor and the power amplifier ground respectively, and the second input end of the current detection module is used for being connected with the power supply ground; the current detection module is used for detecting the resistance current value of the load resistor and outputting a detection signal under the condition that the coil is connected with the power supply ground;

and the control module is connected with the detection signal output end of the current detection module and is used for determining the actual resistance value of the load resistor according to the detection signal.

In one embodiment, the relay control module includes:

the power amplifier signal detection module is used for being connected with the power amplifier output end of the device to be detected, outputting a conduction control signal when the power amplifier output end of the device to be detected is detected to output a power amplifier signal, and outputting a disconnection control signal when the device to be detected is not detected to output the power amplifier signal;

the switch module is respectively connected with the power amplifier signal detection module and the coil and is used for connecting the power amplifier ground; the switch module is used for conducting connection between the coil and the power amplifier ground under the condition that the conducting control signal is received, and disconnecting the coil from the power amplifier ground under the condition that the disconnecting control signal is received.

In one embodiment, the switch module includes:

the first end of the first switch unit is connected with the power amplification signal detection module, and the second end of the first switch unit is used for being connected with a second working power supply;

the first end of the second switch unit is connected with the third end of the first switch unit, the second end of the second switch unit is connected with the coil, and the third end of the second switch unit is used for being connected with the power amplifier ground;

the first switch unit is used for conducting connection between the second end of the first switch unit and the third end of the first switch unit under the condition that the conduction control signal is received, so that the second switch unit conducts connection between the second end of the second switch unit and the third end of the second switch unit; the first switch unit is further configured to disconnect the connection between the second end of the first switch unit and the third end of the first switch unit upon receiving the disconnection control signal, so that the second switch unit disconnects the connection between the second end of the second switch unit and the third end of the second switch unit.

In one embodiment, the switch module further includes a third switch unit, and the load resistance detection circuit further includes a delay conduction module;

the first end of the third switch unit is connected with the third end of the first switch unit, the second end of the third switch unit is used for being connected with the second working power supply, the third end of the third switch unit is used for being connected with the power amplifier ground, and the fourth end of the third switch unit is connected with the control module;

the first end of the delay conduction module is connected with the control module, the second end of the delay conduction module is connected with the coil, and the third end of the delay conduction module is used for being connected with a power amplifier ground;

when the second end of the first switch unit is conducted with the third end of the first switch unit, the third end of the third switch unit is conducted with the fourth end of the third switch unit, so that the fourth end of the third switch unit outputs a low level; when the second end of the first switch unit is disconnected from the third end of the first switch unit, the third end of the third switch unit is disconnected from the fourth end of the third switch unit, so that the fourth end of the third switch unit outputs a high level under the action of the second working power supply;

the control module is used for conducting connection between the second end of the delay conducting module and the third end of the delay conducting module according to preset conducting time when detecting that the fourth end of the third switch unit jumps from low level to high level.

In one embodiment, the first switch unit comprises a first capacitor, a first resistor and a first triode, the second switch unit comprises a second resistor and a second triode, and the third switch unit comprises a third resistor, a fourth resistor and a third triode;

the first end of the first capacitor is used for being connected with the power amplification ground, the second end of the first capacitor is connected with the collector electrode of the first triode and is used for being connected with the second working power supply, the base electrode of the first triode is connected with the first end of the first resistor, and the second end of the first resistor is connected with the power amplification signal detection module; the emitter of the first triode is respectively connected with the first end of the second resistor and the first end of the third resistor; the second end of the second resistor is connected with the base electrode of the second triode, the emitter electrode of the second triode is used for being connected with the power amplifier ground, and the collector electrode of the second triode is connected with the coil;

the second end of the third resistor is connected with the base electrode of the third triode, the collector electrode of the third triode is respectively connected with the control module and the first end of the fourth resistor, and the second end of the fourth resistor is used for being connected with the second working power supply; and the emitter electrode of the third triode is used for being connected with the power amplifier ground.

In one embodiment, the delay conduction module comprises a fifth resistor, a sixth resistor and a fourth triode;

the first end of the fifth resistor is connected with the control module and the first end of the sixth resistor respectively, the second end of the fifth resistor is connected with the base electrode of the fourth triode, the collector electrode of the fourth triode is connected with the coil, and the emitter electrode of the fourth triode and the second end of the sixth resistor are both used for being connected with the power amplifier ground.

In one embodiment, the switch module further includes a filter unit, and the filter unit is connected between the first end of the first switch unit and the power amplifier signal detection module.

In one embodiment, the filtering unit includes a second capacitor, a third capacitor, a seventh resistor, an eighth resistor and a first diode;

the second capacitor and the first diode are sequentially connected between the power amplification signal detection module and the first end of the first switch unit, and the first end of the second capacitor is connected with the power amplification signal detection module; the second end of the second capacitor is respectively connected with the first end of the seventh resistor and the positive electrode of the first diode, and the negative electrode of the first diode is respectively connected with the first end of the first switch unit, the first end of the eighth resistor and the first end of the third capacitor;

the second end of the seventh resistor, the second end of the eighth resistor and the second end of the third capacitor are all used for being connected with the power amplifier ground.

In one embodiment, the load resistance detection circuit further comprises an acousto-optic prompt module and a resistance value setting module;

the control module is respectively connected with the acousto-optic prompting module and the resistance setting module and is used for driving the acousto-optic prompting module to carry out acousto-optic prompting according to the actual resistance of the load resistor so as to enable the acousto-optic prompting module to prompt the actual resistance;

the control module is also used for determining an expected resistance value according to the trigger signal of the resistance value setting module and driving the acousto-optic prompting module to alarm under the condition that the actual resistance value is not equal to the expected resistance value.

In a second aspect, an embodiment of the present application further provides a power amplifier testing device, including:

the load resistance detection circuit of any one of the above embodiments;

and the first end of the load resistor is connected with the movable contact of the relay of the load resistor detection circuit, and the second end of the load resistor is connected with the first input end of the current detection module in the load resistor detection circuit.

In the load resistor detection circuit and the power amplifier testing device provided by some embodiments of the present application, under the condition that the device to be tested outputs a power amplifier signal, the relay control module turns on the connection between the coil of the relay and the power amplifier ground, the coil is powered on, and the movable contact of the relay is connected with the normally open contact of the relay, so that the device to be tested can be connected with the load resistor, and the test of the device to be tested is conveniently completed. Under the condition that the device to be tested does not output a power amplification signal, the relay control module breaks the connection between the coil and the power amplification ground, the coil loses electricity, the movable contact of the relay is connected with the normally-closed contact of the relay, and the first working power supply, the load resistor, the current detection module and the power supply form a loop, so that the current detection module can detect the resistance current value of the load resistor and output a detection signal. The control module can determine the actual resistance value of the load resistor according to the detection signal. The method and the device can timely detect the actual resistance of the load resistor, so that a tester can timely judge whether the actual resistance of the load resistor meets the requirement of the operation guidance parameter or not, and timely replace the load resistor when the load resistor is in a problem. Therefore, the problems of repeated test and incorrect test results can be avoided as far as possible, and the test efficiency and the accuracy of the test results are considered.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive faculty for a person skilled in the art.

FIG. 1 is one of the schematic block diagrams of a load resistance detection circuit in one embodiment;

FIG. 2 is a second schematic block diagram of a load resistance detection circuit in one embodiment;

FIG. 3 is a circuit block diagram of a relay control module according to one embodiment;

FIG. 4 is a circuit diagram of a delay pass module in one embodiment;

fig. 5 is a circuit configuration diagram of a relay, a current detection module, and a control module according to an embodiment.

Detailed Description

The following description of the embodiments of the present application will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all, of the embodiments of the present application. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present disclosure.

In one embodiment, the present application provides a load resistance detection circuit. As shown in fig. 1, the circuit may include a relay, a relay control module 20, a current detection module 30, and a control module 40. The relay may include a coil K, a movable contact, at least one normally closed contact, and at least one normally open contact. When the coil K is powered off, the movable contact is connected with the normally closed contact; when the coil K is electrified, the movable contact is connected with the normally open contact. The relay control module 20 refers to a circuit structure or a device for controlling the power-on/off state of the coil K. The current detection module 30 is a circuit structure or a device capable of detecting a current value in a loop. The control module 40 is a circuit structure or a device having a control function. It should be understood that, in the present application, the specific circuit structures of the relay control module 20, the current detection module 30 and the control module 40 may be determined according to practical situations, which is not limited herein. In one example, the current detection module 30 of the present application may be implemented based on an ACS712-5 model chip, and the control module 40 may be implemented based on an STM single chip.

As shown in fig. 1, the first end of the coil K and the normally-closed contact of the relay are both used for connecting to the first operating power supply, the normally-open contact of the relay is used for connecting to the power amplifier output terminal amp_out of the device under test 10, and the movable contact of the relay is used for connecting to the first end of the load resistor R0. In one example, a first operating power source may be used to provide a 12V voltage.

The relay control module 20 may be connected to the second terminal of the coil K, and is used to connect the power amplifier output terminal amp_out and the power amplifier ground AGND of the device under test 10, respectively. The first input end of the current detection module 30 is used for being connected with the second end of the load resistor R0 and the power amplifier ground AGND respectively, the second input end of the current detection module 30 is used for being connected with the power supply ground PGND, and the detection signal output end of the current detection module 30 is connected with the control module 40. The power amplifier ground AGND refers to the ground to which the power amplifier device in the device under test 10 is connected, and the power supply ground PGND refers to the ground to which the first operating power supply is connected.

Specifically, since the relay control module 20 is connected to the power amplifier output terminal amp_out of the device under test 10, the relay control module 20 can detect whether the device under test 10 outputs the power amplifier signal through its power amplifier output terminal amp_out. In the case where it is detected that the device under test 10 outputs the power amplification signal, the relay control module 20 may turn on the connection between the coil K and the power amplification ground AGND. In this case, the first operating power supply, the coil K and the power amplifier ground AGND form a loop, so that the coil K is powered. When the coil K is powered on, the movable contact of the relay is connected with the normally open contact, so that the power amplifier output end AMP_OUT of the device under test 10 can be connected with the load resistor R0 through the normally open contact and the movable contact. Thus, the tester can test the parameters of the device under test 10 such as the overall power, voltage, noise, distortion, etc.

In the case where the output of the power amplifier signal by the device under test 10 is not detected, the relay control module 20 may disconnect the connection between the coil K and the power amplifier ground AGND. In this case, no loop is formed between the first operating power supply, the coil K, and the power amplifier ground AGND, and the coil K is powered off. When the coil K is powered off, the movable contact of the relay is connected with the normally-closed contact, so that the first working power supply, the load resistor R0, the current detection module 30 and the power ground PGND form a loop, and the current value of the loop is related to the power supply voltage of the first working power supply and the actual resistance value of the load resistor R0. The current detection module 30 may detect a resistance current value in the loop in a case where the coil K is connected to the power ground PGND, and output a detection signal according to the resistance current value, where the detection signal is used to reflect the magnitude of the resistance current value. The control module 40 may determine a resistance current value according to the detection signal, and calculate an actual resistance value of the load resistor R0 based on the resistance current value and a power supply voltage of the first operating power supply.

In the load resistor detection circuit provided by the embodiment of the application, the actual resistance of the load resistor R0 can be detected in time, so that a tester can judge whether the actual resistance of the load resistor R0 meets the requirement of an operation guidance parameter in time, and the load resistor R0 can be replaced in time when the load resistor R0 has a problem. Therefore, the problems of repeated test and incorrect test results can be avoided as far as possible, and the test efficiency and the accuracy of the test results are considered.

In one embodiment, the relay control module 20 may include a power amplifier signal detection module 210 and a switch module connected to the power amplifier signal detection module 210. The switch module may be connected to the second end of the coil K and may be used to connect to the power amplifier ground AGND, and the power amplifier signal detection module 210 is used to connect to the power amplifier output end amp_out of the device under test 10.

Specifically, the power amplifier signal detection module 210 is configured to output a turn-on control signal to the switch module when detecting that the device under test 10 outputs a power amplifier signal. And under the condition that the switch module receives the conduction control signal, the second end of the coil K is connected with the power amplifier ground AGND, so that the coil K is electrified. The power amplifier signal detection module 210 is further configured to output an off control signal to the switch module when the power amplifier signal output by the device under test 10 is not detected. And under the condition that the switch module receives the disconnection control signal, the second end of the coil K is disconnected with the power amplifier ground AGND, so that the coil K is powered off. The relay control module 20 is realized through the power amplification signal detection module 210 and the switch module, and the circuit cost of the load detection circuit is reduced.

In one embodiment, as shown in fig. 2, the switching module of the present application may include a first switching unit 220 and a second switching unit 230. A first end of the first switch unit 220 is connected to the power amplifier signal detection module 210, and a second end of the first switch unit 220 is connected to a second working power supply. Wherein the supply voltage of the second operating power supply may be the same or different from the supply voltage of the first operating power supply, in one example, the supply voltage of the second operating power supply may be 3.3V and 5V.

The third terminal of the first switch unit 220 is connected to the first terminal of the second switch unit 230, the second terminal of the second switch unit 230 is connected to the second terminal of the connection line K, and the third terminal of the second switch unit 230 is connected to the power amplifier AGND. The first switching unit 220 turns on the connection between the second terminal of the first switching unit 220 and the third terminal of the first switching unit 220 in case that the first terminal thereof receives the turn-on control signal, so that the first terminal of the second switching unit 230 may be connected to the second operating power source through the first switching unit 220. When the first end of the second switch unit 230 is connected to the second operating power source, the second switch unit 230 is turned on, that is, the second end of the second switch unit 230 is connected to the third end of the second switch unit 230, so that the second end of the coil K may be connected to the power amplifier ground AGND through the second switch unit 230.

In case that the first switching unit 220 receives the off control signal at the first end thereof, the connection between the second end of the first switching unit 220 and the third end of the first switching unit 220 is disconnected, such that the first end of the second switching unit 230 is not connected to the second operating power source, and thus the second switching unit 230 is also disconnected. When the second switch unit 230 is turned off, the second end of the second switch unit 230 is disconnected from the third end of the second switch unit 230, and thus the connection between the coil K and the power amplifier ground AGND is disconnected, and the coil K loses power.

In the embodiment, the first switch unit 220 and the second switch unit 230 are used to control the power-on/power-off state of the coil K, and the circuit is simple.

In one embodiment, as shown in fig. 2, the switch module may further include a third switch unit 240, and the load detection circuit may further include a delay turn-on module 50. The first end of the third switch unit 240 is connected to the third end of the first switch unit 220, the second end of the third switch unit 240 is connected to the second operating power source, the third end of the third switch unit 240 is connected to the power amplifier ground AGND, and the fourth end of the third switch unit 240 is connected to the control module 40. The first end of the delay conduction module 50 is connected with the control module 40, the second end of the delay conduction module 50 is connected with the second end of the coil K, and the third end of the delay conduction module 50 is used for being connected with the power amplifier ground AGND.

Specifically, when the second end of the first switching unit 220 is turned on with the third end of the first switching unit 220, the first end of the third switching unit 240 may be connected to the second operating power source through the first switching unit 220, so that the third switching unit 240 may be turned on under the power voltage of the second operating power source. When the third switch unit 240 is turned on, the third terminal of the third switch unit 240 is connected to the fourth terminal of the third switch unit 240 to be turned on, so that the fourth terminal of the third switch unit 240 can be connected to the power amplifier ground AGND and output a low level. When the second end of the first switching unit 220 is disconnected from the third end of the first switching unit 220, the first end of the third switching unit 240 is disconnected from the second operating power source, so that the third switching unit 240 is disconnected. In case the third switching unit 240 is turned off, the third terminal of the third switching unit 240 and the fourth terminal of the third switching unit 240 are disconnected. Since the second terminal of the third switching unit 240 is connected to the second operating power, the fourth terminal of the third switching unit 240 may output a high level under the action of the second operating power in case that the third switching unit 240 is turned off. It can be seen that the fourth terminal output level of the third switch unit 240 is associated with whether the device under test 10 is detected to output the power amplifier signal. In the case where it is detected that the device under test 10 outputs the power amplification signal, the fourth terminal of the third switching unit 240 outputs a low level. In the case where the output of the power amplification signal by the device under test 10 is not detected, the fourth terminal of the third switching unit 240 outputs a high level.

The control module 40 is connected to the fourth terminal of the third switch unit 240, and can control the on-off state of the delay pass module 50 according to the output level of the fourth terminal. Specifically, when the transition of the fourth terminal output level of the third switching unit 240 from the low level to the high level is detected, the level transition may indicate that the device under test 10 changes from outputting a normally measurable power amplification signal to outputting a power amplification signal with a small amplitude, or that the device under test 10 changes from outputting a normally measurable power amplification signal to outputting no power amplification signal. In this case, the control module 40 may switch on the connection between the second end of the delay switch-on module 50 and the third end of the delay switch-on module 50 according to the preset switch-on duration, so that the second end of the coil K may remain connected to the power amplifier ground AGND within the preset switch-on duration, so that the tester may continue to test, for example, test the noise of the power amplifier device.

It will be appreciated that the length of the preset on-time may be determined according to the actual situation, and in one example, it may be 5 seconds. When the preset turn-on duration is 5 seconds, the control module 40 can output a turn-on control signal for 5 seconds to the first end of the delay turn-on module 50 when detecting that the output level of the fourth end of the third switch unit 240 jumps from the low level to the high level, so that the delay turn-on module 50 is turned on for 5 seconds, and a tester can conveniently complete the test. Under the condition that the on time of the delay conduction module 50 is greater than or equal to 5 seconds, the control module 40 can output an off control signal to the first end of the delay conduction module 50 to disconnect the connection between the second end and the third end of the delay conduction module 50, so that the load resistance detection circuit can detect the actual resistance value of the load resistance R0.

In one embodiment, as shown in fig. 3, the first switching unit 220 may include a first capacitor C1, a first resistor R1, and a first transistor Q1. The second switching unit 230 may include a second resistor R2 and a second transistor Q2. The third switching unit 240 may include a third resistor R3, a fourth resistor R4, and a third transistor Q3.

The first end of the first capacitor C1 is used for being connected with the power amplifier AGND, the second end of the first capacitor C1 is used for being connected with a second working power supply, and the second end of the first capacitor C1 is also connected with the collector electrode of the first triode Q1. The base of the first triode Q1 is connected with the first end of the first resistor R1, and the second end of the first resistor R1 can be connected with the power amplification signal detection module 210. The emitter of the first triode Q1 is respectively connected with the first end of the second resistor R2 and the first end of the third resistor R3. The second end of the second resistor R2 is connected with the base electrode of the second triode Q2, the collector electrode of the second triode Q2 is connected with the second end of the coil K, and the emitter electrode of the second triode Q2 is used for being connected with the power amplifier ground AGND. The second end of the third resistor R3 is connected with the base electrode of the third triode Q3, the emitter electrode of the third triode Q3 is used for being connected with the power amplifier ground AGND, the collector electrode of the third triode Q3 is respectively connected with the control module 40 and the first end of the fourth resistor R4, and the second end of the fourth resistor R4 is used for being connected with a second working power supply. In the embodiment, each switch unit is realized through a capacitor, a resistor and a triode, and the circuit has the advantages of simple realization and low circuit cost.

In one embodiment, the switching module may further include a filtering unit, which may be connected between the first end of the first switching unit 220 and the power amplification signal detection module 210, in other words, the power amplification signal detection module 210 is connected to the first end of the first switching unit 220 through the filtering unit. The filtering unit can filter the signal output by the power amplification signal detection module 210, prevent voltage mutation, and improve the stability of circuit operation.

It will be appreciated that the specific circuit configuration of the filtering unit may be determined according to practical situations. In one example, as shown in fig. 3, the filtering unit may include a second capacitor C2, a third capacitor C3, a seventh resistor R7, an eighth resistor R8, and a first diode D1. The second capacitor C2 and the first diode D1 are sequentially connected between the power amplifier signal detection module 210 and the first end of the first switch unit 220, that is, the power amplifier signal detection module 210, the second capacitor C2, the first diode D1 and the first end of the first switch unit 220 are sequentially connected. Specifically, the first end of the second capacitor C2 is connected to the power amplifier signal detection module 210, the second end of the second capacitor C2 is connected to the first end of the seventh resistor R7 and the positive electrode of the first diode D1, and the negative electrode of the first diode D1 is connected to the first end of the first switch unit 220, the first end of the eighth resistor R8 and the first end of the third capacitor C3, respectively. The second end of the seventh resistor R7, the second end of the eighth resistor R8 and the second end of the third capacitor C3 are all connected to the power amplifier ground AGND.

The second capacitor C2 may be used to block the dc voltage, and the second capacitor C2 may be discharged through the seventh resistor R7. The third capacitor C3 may be used for filtering and storing electric energy, and is used for stabilizing the dc voltage between the eighth resistor R8 and the first terminal of the first switch unit 220, so as to prevent the output signal of the power amplifier device or the power amplifier signal detection module 210 from suddenly changing to cause unstable circuit. Further, the organization of the eighth resistor R8 may be larger for discharging the electrical energy stored in the third capacitor C3.

In one embodiment, as shown in fig. 4, the delay pass module 50 may include a fifth resistor R5, a sixth resistor R6, and a fourth transistor Q4. The first end of the fifth resistor R5 is connected to the control module 40 and the first end of the sixth resistor R6, respectively, and the second end of the sixth resistor R6 is connected to the emitter of the fourth transistor Q4. The base electrode of the fourth triode Q4 is connected with the second end of the fifth resistor R5, the collector electrode of the fourth triode Q4 is connected with the second end of the coil K, and the emitter electrode of the fourth triode Q4 is used for being connected with the power amplifier ground AGND. In this embodiment, the delay conduction module 50 is implemented by a capacitor, a resistor and a triode, and has the advantages of simple circuit implementation and low circuit cost.

In one embodiment, the load resistance detection circuit may include an audible and visual cue module and a resistance setting module. The control module 40 is respectively connected with the acousto-optic prompting module and the resistance setting module, and is used for driving the acousto-optic prompting module to carry out acousto-optic prompting according to the actual resistance of the load resistor R0 so as to enable the acousto-optic prompting module to prompt the actual resistance. The control module 40 is further configured to determine an expected resistance according to the trigger signal of the resistance setting module, and drive the acousto-optic prompting module to alarm if the actual resistance is not equal to the expected resistance. Therefore, the tester can be reminded more timely, so that the test efficiency and the reliability of the test result are further improved.

It can be appreciated that the acousto-optic cue module and the resistance setting module of the present application can be implemented in any manner. In an example, as shown in fig. 5, the resistance setting module may be implemented based on the KEY1, and the audible and visual prompting module may include a buzzer M1, a plurality of resistors, and a plurality of light emitting diodes, and the connection relationship of the electronic devices may be as shown in fig. 5. In this example, before testing the device under test 10, a tester may manually access the load resistor R0 with a corresponding resistance value according to the requirement of the operation guiding parameter, and set the expected resistance value through the KEY 1. For example, when the control module 40 detects that the KEY1 is pressed 1 time, the expected resistance is set to 4Ω; when the KEY1 is detected to be pressed 2 times, the expected resistance value is set to be 8Ω; when it is detected that KEY1 is pressed 3 times, the expected resistance value is set to 20Ω, and so on. When the requirement of the job guidance parameter is 8Ω, the tester can manually replace the load resistor R0 of 8Ω, and press the KEY1 to set the desired resistance value. It can be understood that the correspondence between the number of presses of the KEY1 and the expected resistance value can be adjusted and determined according to the actual situation.

In one example, the present application may implement the relay control module 20 using the circuit structure shown in fig. 3, implement the delay turn-on module 50 using the circuit structure shown in fig. 4, and implement the relay, the current detection module 30, the control module 40, the acousto-optic cue module, and the resistance setting module using the structure shown in fig. 5.

In this example, the operation state of the load resistance detection circuit can be divided into three cases.

Case one: when the power amplifier output terminal amp_out of the device under test 10 continuously outputs no power amplifier signal, the audio driver SGM8904 chip in the power amplifier signal detection module 210 does not output the ac control signal, and the first triode Q1 and the second triode Q2 are both turned off, so the coil K cannot be connected to the power amplifier ground AGND through the second triode Q2, the coil K is powered off, and the first end of the relay is connected to the fifth end of the relay, so that the load resistor R0 can be connected to the first working power supply and the power supply ground PGND through the P1 base respectively. The first working power supply and the load resistor R0 form a loop and generate a resistor current, the resistor current is input to the 3 rd end and the 4 th end of the ACS712-5, and the ACS712-5 can output a corresponding voltage signal to the 20 th end of the singlechip according to the resistor current value. The singlechip can compare voltage signal and voltage threshold value, if voltage signal is greater than or less than voltage threshold value, then singlechip can drive buzzer M1 sound to indicate that the actual resistance of tester load resistance R0 has the problem. If the voltage signal is equal to the voltage threshold, the buzzer M1 may not sound to indicate that the actual resistance value of the load resistor R0 meets the test requirement.

And a second case: when the power amplifier output terminal amp_out of the device under test 10 outputs the power amplifier signal, the SGM8904 chip outputs an ac control signal to turn on the first transistor Q1. Under the condition that the first triode Q1 is conducted, the second triode Q2 and the third triode Q3 are both conducted, so that the collector electrode of the third triode Q3 outputs a low level. When the singlechip detects that the collector electrode of the third triode Q3 is at a low level, the singlechip outputs the low level to the first end of the fifth resistor R5 so as to cut off the fourth triode Q4. When the second triode Q2 is turned on, the second end of the coil K may be connected to the power amplifier ground AGND through the second triode Q2, the coil K may be powered, and the device under test 10 may be connected to the load resistor R0, so that a tester may test the positive power, voltage, distortion, etc. of the device under test 10 under the load resistor R0.

And a third case: at the moment that the amplitude of the power amplification signal is small, the device to be tested 10 stops outputting the power amplification signal or the device to be tested 10 is disconnected, the SGM8904 chip does not output an alternating current control signal, the first triode Q1 is cut off, and the second triode Q2 and the third triode Q3 are cut off. The collector of the third transistor Q3 outputs a high level. When the singlechip detects that the collector voltage of the third triode Q3 jumps from low level to high level, the singlechip can continuously output the high level for 5 seconds to the fifth resistor R5, so that the fourth triode Q4 is conducted for 5 seconds. Under the condition that the fourth triode Q4 is conducted, the coil K is electrified, and the movable contact of the relay is connected with the normally open contact, so that a tester can test parameters such as power amplifier noise. After 5 seconds, the singlechip can output low level, the coil K loses power, the load resistor R0 is connected with a first working power supply, and the load resistor detection circuit can detect the actual resistance value of the load resistor R0.

In one embodiment, the present application further provides a power amplifier testing device, which includes:

the load resistance detection circuit of any one of the above embodiments;

and a first end of the load resistor R0 is connected with the movable contact of the relay of the load resistor detection circuit, and a second end of the load resistor R0 is connected with the first input end of the current detection module 30 in the load resistor detection circuit.

The specific description of the power amplifier testing device can refer to any of the above embodiments, and will not be repeated herein. The power amplifier testing device can avoid repeated tests and incorrect test results as far as possible, and has the advantages of considering the test efficiency and the accuracy of the test results.

Finally, it is further noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element. Herein, "a," "an," "the," and "the" may also include plural forms, unless the context clearly indicates otherwise. Plural means at least two cases such as 2, 3, 5 or 8, etc. "and/or" includes any and all combinations of the associated listed items.

In the present specification, each embodiment is described in a progressive manner, and each embodiment focuses on the difference from other embodiments, and may be combined according to needs, and the same similar parts may be referred to each other.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present application. 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 application. Thus, the present application 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.

Claims

1. A load resistance detection circuit, comprising:

2. The load resistance detection circuit of claim 1, wherein the relay control module comprises:

3. The load resistance detection circuit of claim 2, wherein the switch module comprises:

4. The load resistance detection circuit of claim 3, wherein the switch module further comprises a third switch unit, the load resistance detection circuit further comprising a delayed turn-on module;

5. The load resistance detection circuit of claim 4, wherein the first switching unit comprises a first capacitor, a first resistor, and a first transistor, the second switching unit comprises a second resistor and a second transistor, and the third switching unit comprises a third resistor, a fourth resistor, and a third transistor;

6. The load resistance detection circuit of claim 4, wherein the delay turn-on module comprises a fifth resistor, a sixth resistor, and a fourth transistor;

7. The load resistance detection circuit according to any one of claims 3 to 6, wherein the switching module further comprises a filter unit connected between the first end of the first switching unit and the power amplifier signal detection module.

8. The load resistance detection circuit according to claim 7, wherein the filter unit includes a second capacitor, a third capacitor, a seventh resistor, an eighth resistor, and a first diode;

9. The load resistance detection circuit according to any one of claims 1 to 6, further comprising an acousto-optic cue module and a resistance setting module;

10. The utility model provides a power amplifier testing arrangement which characterized in that includes:

the load resistance detection circuit according to any one of claims 1 to 9;