CMRR is a key indicator of a medical device's ability to withstand electrical noise. Common mode interference is interference signals coming from external power sources, circuits, or other equipment, and medical devices are often used in high-noise environments, where electromagnetic interference, in particular, can impact the accuracy and reliability of devices.
Therefore, medical standards require CMRR testing to ensure that ECG devices continue to display accurate readouts even in noisy environments. ECG device manufacturers also aim to maximize products' CMRR value to produce clearer, more readable ECG signals.

However, it's challenging for manufacturers to create a dedicated CMRR tester that adheres to the specific circuit and hardware design requirements outlined in medical standards. The circuit must replicate various conditions, such as simulating the capacitance effect (100pF) between the patient bed and the floor, providing a voltage of 20Vrms, and including a parallel circuit of 51kΩ/47nF to simulate the impedance between electrodes and skin. These complex requirements increase design difficulty, and maintenance and calibration for the tester further add to the challenges.

After studying standards and developing the first version, we introduced the CMRR 3.0+. It incorporates a double-layer shielding design for internal circuits to meet regulatory requirements and effectively control noise levels for consistent testing. With a built-in sine wave signal generator and voltage measurement circuit, it eliminates the need for external signal generators, which could introduce extra noise, and ensures sufficient voltage supply for easy test setup.

In addition to providing the standard voltage, the CMRR 3.0+ offers a higher output voltage of up to 70.71Vrms, extending the CMRR test range to 120dB—beyond the 89dB required by standards—helping engineers enhance product specifications.
The CMRR 3.0+ features robust noise isolation, making it suitable for both R&D and production line testing, and when paired with our free software development kit (SDK), it allows efficient automated testing in production.

To further assist manufacturers in compliance testing, we offer exclusive Standard Assistant Software that simplifies the setups of standard test items. Users can simply follow the instructions and select the parameters to easily complete compliance testing.
CMRR forms one of the foundational aspects of medical device excellence. We hope the CMRR 3.0+ can help manufacturers build superior ECG devices by providing reliable and high-quality performance.

 All-in-One Circuit Design to Overcome Testing and Technical Challenges

High CMRR Testing to Enhance Product Competitiveness

• Double-layer shielding structure for minimizing both internal and external noise interference
• Capable of achieving up to 111dB for CMRR in unbalanced testing
• Shielding covers can be added to enable testing for higher CMRR values

 

 Provided SDK for Flexibly Developing Programs as Needed

• Users can develop automated testing software based on their needs to control the testing process, reducing the effort of repetitive setups

 

Standard Assistant Software for Effortlessly Conducting Compliance Tests

• Supports ECG-related international standards IEC 60601-2-25, IEC 60601-2-27, and IEC 60601-2-47, EEG-related international standard IEC 60601-2-26, as well as Chinese regulations GB 9706.225, GB 9706.227, YY 9706.247, GB 9706.226, YY1079, YY1139, YY0782, and YY0885
• Users can follow the step-by-step instructions in the standard assistant software to configure the DUT, select parameters, and conduct compliance testing

Note: The Standard Assistant Software needs a separate purchase.

Comprehensive Compliance Testing Solution

• Saves time studying the medical standard and training by completing performance and database testing required by IEC standards with WhaleTeq ECG testing products

👉IEC 60601-2-25 Testing Package
👉IEC 60601-2-27 Testing Package
👉IEC 60601-2-47 Testing Package