Application of KP2021 High-Frequency Electrosurgical Analyzer and Network Analyzer in Thermage Testing
2025-09-08
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Abstract
Thermage, a non-invasive radiofrequency (RF) skin tightening technology, is widely used in medical aesthetics. With operating frequencies increasing to 1MHz-5MHz, testing faces challenges such as skin effect, proximity effect, and parasitic parameters. Based on the GB 9706.202-2021 standard, this article explores the integrated application of the KP2021 high-frequency electrosurgical analyzer and vector network analyzer (VNA) in power measurement, impedance analysis, and performance validation. Through optimized strategies, these tools ensure the safety and efficacy of Thermage devices.
Keywords: Thermage; KP2021 high-frequency electrosurgical analyzer; network analyzer; high-frequency testing;
IEC 60601-2-20 standard; skin effect; parasitic parameters
Introduction
Thermage is a non-invasive RF skin tightening technology that heats deep collagen layers to promote regeneration, achieving skin tightening and anti-aging effects. As a medical aesthetic device, the stability, safety, and performance consistency of its RF output are critical. According to IEC 60601-2-2 and its Chinese equivalent, GB 9706.202-2021, RF medical devices require testing for output power, leakage current, and impedance matching to ensure clinical safety and efficacy.
High-frequency electrosurgical devices utilize high-density, high-frequency current to create localized thermal effects, vaporizing or disrupting tissue for cutting and coagulation. These devices, typically operating in the 200kHz-5MHz range, are widely used in open surgeries (e.g., general surgery, gynecology) and endoscopic procedures (e.g., laparoscopy, gastroscopy). While traditional electrosurgical units operate at 400kHz-650kHz (e.g., 512kHz) for significant cutting and hemostasis, higher-frequency devices (1MHz-5MHz) enable finer cutting and coagulation with reduced thermal damage, suitable for plastic surgery and dermatology. As higher-frequency devices like low-temperature RF knives and aesthetic RF systems emerge, testing challenges intensify. The GB 9706.202-2021 standard, particularly clause 201.5.4, imposes stringent requirements on measurement instruments and test resistors, rendering traditional methods inadequate.
The KP2021 high-frequency electrosurgical analyzer and vector network analyzer (VNA) play pivotal roles in Thermage testing. This article examines their applications in quality control, production validation, and maintenance, analyzing high-frequency testing challenges and proposing innovative solutions.
Overview and Functions of KP2021 High-Frequency Electrosurgical Analyzer
The KP2021, developed by KINGPO Technology, is a precision testing instrument for high-frequency electrosurgical units (ESUs). Its key features include:
Wide Measurement Range: Power (0-500W, ±3% or ±1W), voltage (0-400V RMS, ±2% or ±2V), current (2mA-5000mA, ±1%), high-frequency leakage current (2mA-5000mA, ±1%), load impedance (0-6400Ω, ±1%).
Frequency Coverage: 50kHz-200MHz, supporting continuous, pulsed, and stimulation modes.
Diverse Test Modes: RF power measurement (monopolar/bipolar), power load curve testing, leakage current measurement, and REM/ARM/CQM (return electrode monitoring) testing.
Automation and Compatibility: Supports automated testing, compatible with brands like Valleylab, Conmed, and Erbe, and integrates with LIMS/MES systems.
Compliant with IEC 60601-2-2, the KP2021 is ideal for R&D, production quality control, and hospital equipment maintenance.
Overview and Functions of Network Analyzer
The vector network analyzer (VNA) measures RF network parameters, such as S-parameters (scattering parameters, including reflection coefficient S11 and transmission coefficient S21). Its applications in medical RF device testing include:
Impedance Matching: Evaluates RF energy transfer efficiency, reducing reflection losses to ensure stable output under varying skin impedances.
Frequency Response Analysis: Measures amplitude and phase responses across a wide band (10kHz-20MHz), identifying distortions from parasitic parameters.
Impedance Spectrum Measurement: Quantifies resistance, reactance, and phase angle via Smith chart analysis, ensuring compliance with GB 9706.202-2021.
Compatibility: Modern VNAs (e.g., Keysight, Anritsu) cover frequencies up to 70GHz with 0.1dB accuracy, suitable for RF medical device R&D and validation.
These capabilities make VNAs ideal for analyzing Thermage’s RF chain, complementing traditional power meters.
Standard Requirements and Technical Challenges in High-Frequency Testing
Overview of GB 9706.202-2021 Standard
Clause 201.5.4 of GB 9706.202-2021 mandates that instruments measuring high-frequency current provide true RMS accuracy of at least 5% from 10kHz to five times the device’s fundamental frequency. Test resistors must have a rated power at least 50% of the test consumption, with resistance component accuracy within 3% and an impedance phase angle not exceeding 8.5° in the same frequency range.
While these requirements are manageable for traditional 500kHz electrosurgical units, Thermage devices operating above 4MHz face significant challenges, as resistor impedance characteristics directly impact power measurement and performance evaluation accuracy.
Key Characteristics of Resistors at High Frequencies
Skin Effect
The skin effect causes high-frequency current to concentrate on a conductor’s surface, reducing effective conductive area and increasing the resistor’s actual resistance compared to DC or low-frequency values. This can lead to power calculation errors exceeding 10%.
Proximity Effect
The proximity effect, occurring alongside the skin effect in closely arranged conductors, exacerbates uneven current distribution due to magnetic field interactions. In Thermage’s RF probe and load designs, this increases losses and thermal instability.
Parasitic Parameters
At high frequencies, resistors exhibit non-negligible parasitic inductance (L) and capacitance (C), forming a complex impedance Z = R + jX (X = XL - XC). Parasitic inductance generates reactance XL = 2πfL, increasing with frequency, while parasitic capacitance generates reactance XC = 1/(2πfC), decreasing with frequency. This results in a phase angle deviation from 0°, potentially exceeding 8.5°, violating standards and risking unstable output or overheating.
Reactive Parameters
Reactive parameters, driven by inductive (XL) and capacitive (XC) reactances, contribute to impedance Z = R + jX. If XL and XC are unbalanced or excessive, the phase angle deviates significantly, reducing power factor and energy transfer efficiency.
Limitations of Non-Inductive Resistors
Non-inductive resistors, designed to minimize parasitic inductance using thin-film, thick-film, or carbon-film structures, still face challenges above 4MHz:
Residual Parasitic Inductance: Even small inductance produces significant reactance at high frequencies.
Parasitic Capacitance: Capacitive reactance decreases, causing resonance and deviating from pure resistance.
Wideband Stability: Maintaining phase angle ≤8.5° and resistance accuracy ±3% from 10kHz-20MHz is challenging.
High-Power Dissipation: Thin-film structures have lower heat dissipation, limiting power handling or requiring complex designs.
Integrated Application of KP2021 and VNA in Thermage Testing
Test Workflow Design
Preparation: Connect KP2021 to the Thermage device, setting load impedance (e.g., 200Ω to simulate skin). Integrate VNA into the RF chain, calibrating to eliminate cable parasitics.
Power and Leakage Testing: KP2021 measures output power, voltage/current RMS, and leakage current, ensuring compliance with GB standards, and monitors REM functionality.
Impedance and Phase Angle Analysis: VNA scans the frequency band, measures S-parameters, and calculates phase angle. If >8.5°, adjust matching network or resistor structure.
High-Frequency Effect Compensation: KP2021’s pulse mode testing, combined with VNA’s time-domain reflectometry (TDR), identifies signal distortions, with digital algorithms compensating for errors.
Validation and Reporting: Integrate data into automated systems, generating GB 9706.202-2021-compliant reports with power load curves and impedance spectra.
KP2021 simulates skin impedances (50-500Ω) to quantify skin/proximity effects and correct readings. VNA’s S11 measurements calculate parasitic parameters, ensuring a power factor close to 1.
Innovative Solutions
Resistor Material and Structure Optimization
Low-Inductance Design: Use thin-film, thick-film, or carbon-film resistors, avoiding wire-wound structures.
Low Parasitic Capacitance: Optimize packaging and pin design to minimize contact area.
Wideband Impedance Matching: Employ parallel low-value resistors to reduce parasitic effects and maintain phase angle stability.
High-Precision High-Frequency Instruments
True RMS Measurement: KP2021 and VNA support non-sinusoidal waveform measurement across 30kHz-20MHz.
Wideband Sensors: Select low-loss, high-linearity probes with controlled parasitic parameters.
Calibration and Validation
Regularly calibrate systems using certified high-frequency sources to ensure accuracy.
Test Environment and Connection Optimization
Short Leads and Coaxial Connections: Use high-frequency coaxial cables to minimize losses and parasitics.
Shielding and Grounding: Implement electromagnetic shielding and proper grounding to reduce interference.
Impedance Matching Networks: Design networks to maximize energy transfer efficiency.
Innovative Testing Methods
Digital Signal Processing: Apply Fourier transforms to analyze and correct parasitic distortions.
Machine Learning: Model and predict high-frequency behavior, auto-adjusting test parameters.
Virtual Instrumentation: Combine hardware and software for real-time monitoring and data correction.
Case Study
In testing a 4MHz Thermage system, initial results showed a 5% power deviation and a 10° phase angle. KP2021 identified excessive leakage current, while VNA detected a 0.1μH parasitic inductance. After replacing with low-inductance resistors and optimizing the matching network, the phase angle dropped to 5°, and power accuracy reached ±2%, meeting standards.
Conclusion
The GB 9706.202-2021 standard highlights the limitations of traditional testing in high-frequency environments. The integrated use of KP2021 and VNA addresses challenges like skin effect and parasitic parameters, ensuring Thermage devices meet safety and efficacy standards. Future advancements, incorporating machine learning and virtual instrumentation, will further enhance testing capabilities for high-frequency medical devices.
https://www.batterytestingmachine.com/videos-51744861-kp2021-electrosurgical-unit-analyzer.html
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KINGPO will meet you at the 92nd China International Medical Equipment (Autumn) Expo in 2025
2025-08-28
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Canton Fair Complex & KINGPO Technology Exhibition
About the Canton Fair Complex
The China Import and Export Fair Complex (also known as the Canton Fair Complex) is located on Pazhou Island in Guangzhou's Haizhu District. With a total construction area exceeding 1.62 million square meters and an exhibition area of 620,000 square meters, including 504,000 square meters of indoor exhibition space and 116,000 square meters of outdoor exhibition space, the Canton Fair Complex is the world's largest convention and exhibition complex. The complex comprises Pavilions A, B, C, and D, the Canton Fair Hall, and Canton Fair Building Towers A (the Westin Canton Fair Hotel) and B. The Canton Fair Complex boasts a prime location and convenient transportation, adjacent to key urban development areas such as Zhujiang New Town, the Pazhou E-commerce Zone, Guangzhou Science City, and Guangzhou University Town. The complex seamlessly integrates humanistic principles, green ecology, high technology, and intelligent technology, shining like a dazzling pearl to the world. As a national-level exhibition platform, the Canton Fair Complex is not only the venue for the China Import and Export Fair (Canton Fair), known as "China's No. 1 Exhibition," but also serves as a premium platform for brand exhibitions and diverse events, as well as a premier venue for high-end international and domestic conferences. Address: No. 382, Yuejiang Middle Road, Haizhu District, Guangzhou
Transportation Guide
Subway Transportation
You can take Metro Line 8 to the Canton Fair Complex. Exit A of Xingangdong Station leads to Canton Fair Complex Area A. Exits A and B of Pazhou Station lead to Canton Fair Complex Area B. Exit C of Pazhou Station and walk 300 meters west to Canton Fair Complex Area C.
Airport North Station/South Station-----Xingang East Station/Pazhou Station
Line 1 (North Extension) Airport North Station (Terminal 2)/Airport South Station (Terminal 1) - Tiyuxi Road Station (Transfer to Line 3) - Kecun Station (Transfer to Line 8) - Xingangdong Station (Canton Fair Complex Area A)/Pazhou Station (Canton Fair Complex Areas B and C)
From the train station to the Canton Fair Complex
From Guangzhou Railway Station: Take Metro Line 2 (towards Guangzhou South Station) to Changgang Station, transfer to Line 8 (towards Wanshengwei Station), and exit at Xingangdong Station (Area A) or Pazhou Station (Areas B or C). From Guangzhou East Railway Station: Take Metro Line 3 (towards Panyu Square Station) to Kecun Station, transfer to Line 8 (towards Wanshengwei Station), and exit at Xingangdong Station (Area A) or Pazhou Station (Areas B or C). From Guangzhou South Station: Take Metro Line 2 (towards Jiahewanggang Station) to Changgang Station, transfer to Line 8 (towards Wanshengwei Station), and get off at Xingangdong Road Station (for Exhibition Hall Area A) or Pazhou Station (for Exhibition Hall Areas B and C). Taxis are an essential part of Guangzhou's public transportation system. They are convenient and fast, stop by simply waving your hand, and fares are metered. Please note: Taxis can only pick up and drop off passengers at the taxi lane on Zhanchangzhong Road in Exhibition Hall Area A and the pick-up point on the east side of Exhibition Hall Area C. Pickup and drop-off are not permitted at other locations. For driving directions, simply navigate to the Canton Fair Complex.
Canton Fair Complex Area A, No. 380, Yuejiang Middle Road, Haizhu District, Guangzhou City, Guangdong Province
KINGPO Technology Exhibits and Services
KINGPO Technology Exhibits and Services As a company specializing in the research and development and manufacturing of medical devices, Dongguan KINGPO Machinery Technology Co., Ltd. has always been committed to providing customers with high-quality products and services. At this exhibition, we will showcase the latest medical device products and technologies, including but not limited to:
Domestically developed IEC60601:Electrosurgical Unit Analyzer, neutral electrode temperature rise tester, impedance tester, etc.
Domestically developed YY1712 solution: surgical robot testing solution
Various defibrillator pulse generators
EEG signal simulator
ISO80369/YY0916 full range of solutions
IVD (IEC61010.GB42125 series standards) testing solutions
Electrical stimulation quality analysis system
Reliability Solutions
Smart Manufacturing Solutions: Provide efficient and intelligent production solutions to help medical device manufacturers improve production efficiency.
Professional services: Our team of experts will answer your questions on site and provide professional technical support and consulting services.
To ensure you can visit our booth smoothly, we have specially provided a registration portal. By scanning the QR code below to register, you will be able to enjoy the privilege of skipping the line on site and learn more about our products and services more efficiently.
We look forward to meeting you at CMEF to discuss the future of the medical device industry. Dongguan Jingbang Machinery Technology Co., Ltd. remains committed to technological innovation and service excellence, working with you to create a better future. Please remember our booth number: 19.2G22. We'll be waiting for you in Guangzhou! We look forward to seeing you!
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Is defibrillation protection testing done correctly?
2025-08-25
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Is defibrillation protection testing done correctly?
Defibrillator protection, a fundamental safety and performance requirement for many medical devices, is required by numerous standards for testing, including common-mode, differential-mode, and energy reduction tests. This requirement itself is likely familiar to many, as it already exists in older versions of the GB 9706 series and other industry standards. These standards also provide circuit diagrams for reference, and everyone has been following this practice for years, seemingly without issue. However, a veteran in the industry recently raised concerns about issues with the defibrillator circuitry in the standards, particularly the signal source connection in the ECG standard. This meticulous individual even simulated the circuit.
If the signal source connection is as per the standard, it should be as shown in Figure 1. However, the output will be close to 20V, and the ECG monitor will probably be saturated early. It is also impossible to achieve the 5mV required by the standard. If the signal source is 5mV as per the standard, the connection method should be as shown in the figure below.
Clearly, the circuit in GB 9706.227-2021 is problematic. So, let's look at the IEC 60601-2-27:2011 version of GB 9706.227-2021. The circuit is as follows (though this circuit also has its own issues).
But why are GB 9706.227-2021 and IEC 60601-2-27:2011 different? The problem may lie with IEC 60601-2-27:2011+C1:2011. This revision requires the common-mode test circuit in the French version to be replaced as follows:
This results in different common-mode defibrillation test circuits in the English and French versions. Domestic converters may have used the latest revision. In fact, both circuits have some issues. Looking back at the IEC 60601-2-27:2005 version, the circuit is as follows:
There are still many differences between this and the 2011 version, but it is consistent with the previous domestic GB 9706.25-2005.
Let's look at the EEG standard, which is similar to the ECG standard: Since there is no common mode test requirement in GB 9706.26-2005, we will directly look at GB9706.226-2021
This is similar to the revised version of IEC 60601-2-27, but it also has some problems, especially when loading the signal source after defibrillation. Let's look at the latest version of the EEG standard IEC 80601-2-26:2019. This is more clear. R1 (100Ω) and R2 (50Ω) are used during defibrillation. After defibrillation, switch to the signal source and use R4 (100Ω) and R2 (50Ω).
Let's look at the upcoming ECG standard IEC 80601-2-86. Apparently, the IEC has recognized its previous mistakes and has updated the common-mode test circuit, which is essentially consistent with IEC 80601-2-26:2019. However, there's one detail worth noting: the resistance value of R3 is different: 470kΩ in one case and 390kΩ in the other.
Therefore, it's almost certain that there's something wrong with the common-mode defibrillation circuit in the current standard. Why hasn't anyone noticed this? I suspect that while the standard includes circuit diagrams for defibrillation testing, most people don't have the luxury of setting up their own circuits for actual testing. The most commonly used devices in the industry are the German Zeus and the US Compliance West MegaPulse. The internal circuitry of these devices is rarely studied. Furthermore, when testing common-mode defibrillation, the signal amplitude is adjusted to meet the standard's requirements before defibrillation. Then, defibrillation is performed, and the signal source is switched back on to compare the amplitude changes before and after defibrillation. Therefore, as long as the test is completed, little attention is paid to the specific details of the internal circuitry.
Now that we've discovered this issue, let's examine the internal circuitry details of these two devices. First, let's look at the internal circuit diagram provided by Zeus: Clearly, the 100Ω resistor is shared, R4 switches between 50Ω and 400Ω, and the signal source only uses a 470kΩ resistor. Furthermore, due to the output circuit connector design, switching the connectors before and after defibrillation is required to load the signal source. Therefore, EEG testing should present no significant issues, and will likely continue to do so. For ECG testing, there are minor discrepancies in the resistor values (although I personally believe this isn't a significant issue, as long as the signal amplitude can be adjusted).
The latest Zeus V1 and V2 circuit diagrams show a change in resistors to 390kΩ, with the addition of R7 and R8. Although the values aren't marked, it's likely this is intended to meet both EEG and ECG requirements.
Compliance West's MegaPulse offers a variety of models, with the D5-P 2011V2 clearly meeting the latest and future ECG standards and providing an accurate connection scheme (even without the separate R4), but it's less suitable for EEG.
Looking at the D5-P circuit, it meets EEG and earlier ECG standards, but not ECG.
Finally, the latest D8-PF signal clearly takes into account the latest EEG and ECG standards.
Therefore, if you want to strictly follow the defibrillator common mode test, you may need to check the model and manual of your defibrillator test equipment to ensure that the internal circuit meets the correct standard requirements. Although strictly speaking, changes in standards have little impact on test results, it is still a concern if you encounter a teacher who is too picky.
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Surgical Robot Positioning Accuracy Test System - Professional Testing Solution Compliant with YY/T 1712-2021 Standard
2025-08-19
Kingpo Technology Development Limited has launched a professional and comprehensive precision testing system for positioning accuracy and control performance, the core performance indicators of surgical robots (RA). Designed in strict accordance with the national pharmaceutical industry standard YY/T 1712-2021, the system offers two core testing solutions: navigation-guided positioning accuracy testing and master-slave control performance testing, ensuring that the equipment meets stringent clinical safety and reliability requirements.
System hardware solution
1. Overview of the core testing solution1) RA equipment accuracy testing solution under navigation guidanceObjective: To evaluate the static and dynamic positioning accuracy of a surgical robot guided by an optical navigation system.
Core indicators: position accuracy and position repeatability.
2) Master-slave control RA device accuracy detection solutionPurpose: To evaluate the motion tracking performance and latency between a master manipulator (doctor side) and a slave robotic arm (surgery side).Core indicator: Master-slave control delay time.
System schematic diagram
2. Detailed explanation of the navigation guidance positioning accuracy detection scheme
This solution uses a high-precision laser interferometer as the core measurement equipment to achieve real-time and accurate tracking of the spatial position of the end of the robotic arm.
1) System hardware core components:Laser interferometer:
Name
Parameter
Brand and model
CHOTEST GTS3300
Spatial measurement accuracy
15μm+6μm/m
Interference ranging accuracy
0.5μm/m
Absolute ranging accuracy
10μm (full range)
Measuring radius
30 meters
Dynamic Speed
3 m/s, 1000 points/s output
Target Recognition
Target ball diameter supports 0.5~1.5 inches
Working environment temperature
Temperature 0~40℃ Relative humidity 35~80%
Protection level
IP54, dust and splash proof, suitable for industrial field environments
Dimensions
Tracking head dimensions: 220×280×495mm, weight: 21.0kg
Laser Tracker Target (SMR):
Name
Parameter
Target ball model
ES0509 AG
Ball diameter
0.5 inches
Center accuracy
12.7um
Retroreflective mirror material
Aluminum/G Glass
Tracking distance
≥40
Name
Parameter
Target ball model
ES1509 AG
Ball diameter
1.5 inches
Center accuracy
12.7um
Retroreflective mirror material
Aluminum/G Glass
Tracking distance
≥50
Positioning robot arm end adapter, control software, and data analysis platform
2) Key test items and methods (based on YY/T 1712-2021 5.3):Position accuracy detection:
(1) Securely mount the target (SMR) on the end of the positioning robot arm.(2) Control the robotic arm so that the end-calibration finger measurement point is within the effective workspace.(3) Define and select a cube with a side length of 300 mm in the workspace as the measurement space.(4) Use the control software to drive the calibration finger measurement point to move along the preset path (starting from point A, moving along B-H and the intermediate point J in sequence).(5) The laser interferometer measures and records the actual spatial coordinates of each point in real time.(6) Calculate the deviation between the actual distance of each measurement point to the starting point A and the theoretical value to evaluate the spatial position accuracy.
Position repeatability detection:
(7) Install the target and start the device as above.(8) Control the end of the robotic arm to reach any two points in the effective workspace: point M and point N.(9) The laser interferometer accurately measures and records the initial position coordinates: M0 (Xm0, Ym0, Zm0), N0 (Xn0, Yn0, Zn0).(10) In automatic mode, the control device returns the laser target measuring point to point M and records the position M1 (Xm1, Ym1, Zm1).(11) Continue to control the device to move the measuring point to point N and record position N1 (Xn1, Yn1, Zn1).(12) Repeat steps 4-5 multiple times (typically 5 times) to obtain the coordinate sequences Mi( Xmi , Ymi , Zmi) and Ni(Xni , Yni , Zni) (i =1,2,3,4,5).(13) Calculate the dispersion (standard deviation or maximum deviation) of the multiple return positions of point M and point N to evaluate the position repeatability.
3. Detailed explanation of the master-slave control performance test solutionThis solution focuses on evaluating the real-time and synchronization performance of master-slave operations of surgical robots.1) System hardware core components:Master-slave signal acquisition and analyzer:Linear motion generating device, rigid connecting rod, high-precision displacement sensor (monitoring the displacement of the master end handle and the slave end reference point).
2) Key test items and methods (based on YY/T 1712-2021 5.6):Master-slave control delay time test:(1) Test setup: Connect the master handle to the linear motion generator via a rigid link. Install high-precision displacement sensors at the reference points of the master handle and slave arm.(2) Motion protocol: Set the master-slave mapping ratio to 1:1.(3) Master end reference point motion requirements:Accelerate to 80% rated speed within 200ms.Maintain a constant speed for a distance.Decelerate to a complete stop within 200ms.(4) Data acquisition: Use a master-slave signal acquisition analyzer to synchronously record the displacement-time curves of the master and slave displacement sensors with high precision and high density.(5) Delay calculation: Analyze the displacement-time curve and calculate the time difference from when the master starts moving to when the slave starts responding (motion delay) and from when the master stops moving to when the slave stops responding (stop delay).(6) Repeatability: The X/Y/Z axis of the device is tested three times independently, and the final results are averaged.
4. Product Core Advantages and ValueAuthoritative compliance: Testing is carried out in strict accordance with the requirements of the YY/T 1712-2021 "Assisted Surgical Equipment and Assisted Surgical Systems Using Robotic Technology" standard.High-precision measurement: The core adopts the Zhongtu GTS3300 laser interferometer (spatial accuracy 15μm+6μm/m) and ultra-high precision target sphere (center accuracy 12.7μm) to ensure reliable measurement results.Professional solution coverage: One-stop solution to the two most critical core performance testing needs of surgical robots : navigation and positioning accuracy (position accuracy, repeatability) and master-slave control performance (delay time).Industrial-grade reliability: Key equipment has an IP54 protection level, suitable for industrial and medical R&D environments.High-performance data acquisition: Master-slave delay testing uses a 24-bit resolution, 204.8kHz synchronous sampling analyzer to accurately capture millisecond-level delay signals.Operational standardization: Provide clear and standardized testing procedures and data processing methods to ensure the consistency and comparability of tests.
Summary
The surgical robot positioning accuracy test system of Kingpo Technology Development Limited is an ideal professional tool for medical device manufacturers, quality inspection agencies and hospitals to conduct surgical robot performance verification, factory inspection, type inspection and daily quality control, providing solid testing guarantees for the safe, accurate and reliable operation of surgical robots.
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IEC 62368-1 Test requirements for equipment containing audio amplifiers
2025-08-14
IEC 62368-1 Test requirements for equipment containing audio amplifiers
According to the ITU-R 468-4 (Measurement of audio noise levels in sound broadcasting) specification, the 1000Hz frequency response is 0dB (see the figure below), which is suitable as a reference level signal and is convenient for evaluating the frequency
response performance of audio amplifiers. Peak response frequency signal. If the manufacturer declares that the audio amplifier is not intended to operate under 1000Hz conditions, the audio signal source frequency should be replaced by the peak response frequency. The peak response frequency is the signal source frequency when the maximum output power is measured on the rated load impedance (hereinafter referred to as the speaker) within the intended operating range of the audio amplifier. In actual operation, the inspector can fix the signal source amplitude and then sweep the frequency to check that the signal source frequency corresponding to the maximum effective value voltage appearing on the speaker is the peak response frequency.
Output power type and regulation - maximum output power
The maximum output power is the maximum power that the speaker can obtain, and the corresponding voltage is the maximum effective value voltage. Common audio amplifiers often use OTL or OCL circuits based on the working principle of Class AB amplifiers. When a 1000Hz sine wave audio signal is input into the audio amplifier and enters the saturation region from the amplification region, the signal amplitude cannot continue to increase, the peak voltage point is limited, and flat-top distortion appears at the peak.
Using an oscilloscope to test the speaker's output waveform, you can find that when the signal is amplified to the effective value and cannot be further increased, peak distortion occurs (see Figure 2). At this time, it is considered that the maximum output power state has been reached. When peak distortion occurs, the crest factor of the output waveform will be lower than the sine wave crest factor of 1.414 (as shown in Figure 2, crest factor = peak voltage / effective value voltage = 8.00/5.82≈1.375＜1.414)
Figure 2: 1000Hz sine wave signal input condition, speaker output waveform at maximum output power
Output power type and adjustment - non-clipped output power,Non-clipped output power refers to the output power at the junction of the saturation zone and the amplification zone when the speaker is operating at maximum output power and without peak distortion (the operating point is biased towards the amplification zone). The audio output waveform presents a complete 1000Hz sine wave with no peak distortion or clipping, and its RMS voltage is also less than the RMS voltage at maximum output power (see Figure 3).
Figure 3 shows the output waveform of the speaker entering the non-clipping output power state after reducing the amplification factor (Figures 2 and 3 show the same audio amplifier network)
Because audio amplifiers operate at the interface between the amplification and saturation regions and are unstable, signal amplitude jitter (the upper and lower peaks may not be equal) can be generated. The crest factor can be calculated using 50% of the peak-to-peak voltage as the peak voltage. In Figure 3 , the peak voltage is 0.5 × 13.10V = 6.550V , and the RMS voltage is 4.632V . The crest factor = peak voltage / RMS voltage = 6.550 / 4.632 ≈ 1.414. Output Power Type and Regulation - Power Regulation Methods. Audio amplifiers receive small signal inputs, amplify them, and output them to the speakers. The gain ratio is typically adjusted using a detailed volume scale (for example, a television's volume adjustment can range from 30 to 100 steps). However, adjusting the gain ratio by adjusting the signal source amplitude is much less effective. Reducing the signal source amplitude, even with the amplifier's high gain, will still significantly reduce the speaker's output power (see Figure 4). In
Figure 4: Output waveform when the speaker enters a non-clipped output power state after reducing the signal source amplitude.
(Figures 2 and 4 show the same audio amplifier network)
Figure 3 , adjusting the volume returns the speaker from maximum output power to a non-clipping state, with an RMS voltage of 4.632V . In Figure 4 , by adjusting the signal source amplitude, the speaker is adjusted from the maximum output power state to the non-clipped output power state, and the effective value voltage is 4.066V . According to the power calculation formula
Output power = square of voltage RMS / speaker impedance
The non-clipped output power of Figure 3 exceeds that of Figure 4 by about 30%, so Figure 4 is not the true non-clipped output power state.
It can be seen that the correct way to call back from the maximum output power state to the non-clipping output power state is to fix the signal source amplitude and adjust the amplification factor of the audio amplifier, that is, to adjust the volume of the audio amplifier without changing the signal source amplitude.
Output power type and adjustment - 1/8 non-clipped output power
Normal operating conditions for audio amplifiers are designed to simulate the optimal operating conditions of real-world speakers. Although real-world sound characteristics vary greatly, the crest factor of most sounds is within 4 (see Figure 5).
Figure 5: A real-world sound waveform with a crest factor of 4
Taking the sound waveform in Figure 5 as an example, crest factor = peak voltage / RMS voltage = 3.490 / 0.8718 = 4. To achieve distortion-free target sound, an audio amplifier must ensure that its maximum peak is free of clipping. If a 1000Hz sine wave signal source is used as a reference, to ensure the waveform remains undistorted and the 3.490V peak voltage is not current-limited, the RMS signal voltage should be 3.490V / 1.414 = 2.468V. However, the RMS voltage of the target sound is only 0.8718V. Therefore, the reduction ratio of the target sound to the RMS voltage of the 1000Hz sine wave signal source is 0.8718 / 2.468 = 0.3532. According to the power calculation formula, the voltage RMS reduction ratio is 0.3532, which means that the output power reduction ratio is 0.3532 squared, which is approximately equal to 0.125=1/8.
Therefore, by adjusting the speaker output power to 1/8 of the non-clipped output power corresponding to the 1000Hz sine wave signal source, the target sound with no distortion and a crest factor of 4 can be output. In other words, 1/8 of the non-clipped output power corresponding to the 1000Hz sine wave signal source is the optimal working state for the audio amplifier to output the target sound with a crest factor of 4 without loss.
The operating state of the audio amplifier is based on the speaker providing 1/8 non-clipping output power. When in the non-clipping output power state, adjust the volume so that the effective value voltage drops to about 35.32%, which is 1/8 non-clipping output power. Because pink noise is more similar to real sound, after using a 1000Hz sine wave signal to obtain non-clipping output power, pink noise can be used as the signal source. When using pink noise as the signal source, it is necessary to install a bandpass filter as shown in the figure below to limit the noise bandwidth.
Normal and abnormal working conditions - normal working conditions
Different types of audio amplifier equipment should consider all of the following conditions when setting normal operating conditions:
- The audio amplifier output is connected to the most unfavorable rated load impedance, or the actual speaker (if provided);
——All audio amplifier channels work simultaneously;
- For an organ or similar instrument with a tone generator unit, instead of using a 1000 Hz sine wave signal, depress the two bass pedal keys (if any) and the ten manual keys in any combination. Activate all stops and buttons that increase the output power, and adjust the instrument to 1/8 of the maximum output power;
- If the intended function of the audio amplifier is determined by the phase difference between the two channels, the phase difference between the signals applied to the two channels is 90°;
For multi-channel audio amplifiers, if some channels cannot operate independently, connect the rated load impedance and adjust the output power to 1/8 of the amplifier's designed non-clipped output power.
If continuous operation is not possible, the audio amplifier operates at the maximum output power level that allows continuous operation.
Normal and abnormal working conditions - Abnormal working conditions
The abnormal working condition of the audio amplifier is to simulate the most unfavorable situation that may occur on the basis of normal working conditions. The speaker can be made to work at the most unfavorable point between zero and maximum output power by adjusting the volume, or by setting the speaker to short circuit, etc.
Normal and abnormal working conditions - temperature rise test placement
When conducting a temperature rise test on an audio amplifier, place it in the position specified by the manufacturer. If there is no special statement, place the device in a wooden test box with an open front, 5 cm from the front edge of the box, with 1 cm of free space along the sides or top, and 5 cm from the back of the device to the test box. The overall placement is similar to simulating a home TV cabinet.
Normal and abnormal working conditions - noise filtering and fundamental wave restoration The noise of some digital amplifier circuits will be transmitted to the speaker along with the audio signal, causing disordered noise to appear when the oscilloscope detects the speaker output waveform. It is recommended to use the simple signal filtering circuit shown in the figure below (the method of use is: points A and C are connected to the speaker output end, point B is connected to the audio amplifier reference ground/loop ground, and points D and E are connected to the oscilloscope detection end). This can filter out most of the noise and restore the 1000Hz sinusoidal fundamental wave to a large extent (1000F in the figure is a typo, it should be 1000pF).
Some audio amplifiers have superior performance and can solve the problem of peak distortion, so that the signal will not be distorted or clipped when it is adjusted to the maximum output power state. At this time, the non-clipping output power is equivalent to the maximum output power. When visible clipping cannot be established, the maximum output power can be regarded as the non-clipping output power.
Electric energy source classification and safety protection
Audio amplifiers can amplify and output high-voltage audio signals, so the audio signal energy source must be classified and protected. When classifying, be sure to set the tone controller to a balanced position, allowing the audio amplifier to operate at maximum non-clipped output power to the speaker. Then, remove the speaker and test the open-circuit voltage. The audio signal energy source classification and safety protection are shown in the table below.
Audio signal electrical energy source classification and safety protection
Energy source level
Audio signal RMS voltage (V)
Example of safety protection between energy source and general personnel
Example of safety guarding between energy source and instructed personnel
ES1
≤71
No safety protection required
No safety protection required
ES2
>71 and ≤120
Terminal insulation (accessible parts non-conductive):
Indicates ISO 7000 0434a code symbol or 0434b code symbol
No safety protection required
Terminals are not insulated (terminals are conductive or wires are exposed):
Mark with indicative safety precautions, such as "touching uninsulated terminals or wires may cause discomfort"
ES3
>120
Use connectors that comply with IEC 61984 and are marked with the 6042 coding symbols of IEC 60417
Pink Noise Generator
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