Summary

In the microscopic realm of medical diagnosis, bioelectrical signals act as the golden key to unlocking the mysteries of life. From the millivolt-level fluctuations in electrocardiograms (ECGs) to the microvolt-level oscillations in electroencephalograms (EEGs), accurately capturing these signals is crucial for early disease detection. The CBM24AD98Q chip from Corebai Microelectronics, a low-noise analog-to-digital converter (ADC) utilizing 24-bit Δ-Σ technology, features an ultra-low noise level of 4μV and an 8-channel highly integrated design. It supports an industrial-grade wide temperature range, making it particularly suitable for bioelectric acquisition applications such as electrocardiograms (ECGs) and extracranial electroencephalograms (EEGs). The CBM24AD98Q chip's superior performance addresses key challenges in the field of medical wwwww bioelectric acquisition, enabling domestic medical devices to compete with international advanced levels.

1、Industry dilemma: the "impossible triangle" of bioelectricity collection

1. The "invisibility" of weak signals: diagnostic blind spots under noise masking

In traditional 16-bit SAR ADC, the quantization noise typically exceeds 10μVPP, which can introduce significant errors in signal processing, similar to adding a 'blur filter' to the signal. For instance, in ECG monitoring, a 0.1mV ST-segment offset is an early sign of myocardial ischemia; however, due to noise interference from a 16-bit ADC, this can result in a false-negative rate of over 30%. In EEG, the brain α waves, which range from 10 to 100μV, are often drowned out by environmental noise, leading to localization errors of epilepsy foci exceeding 10mm.

2. The "bulking up" of multi-channel systems: the volume and cost trap of imported solutions

To construct a standard 12-lead ECG, three external differential amplifiers are required to generate the reference voltage. In some imported solutions, this requires more than five chips to work together, resulting in a circuit area exceeding 100cm² and making the device generally exceed 3L in size. This not only increases costs by 50% but also leads to a persistently low procurement rate for basic medical equipment, below 20%. As a result, township health centers often abandon the multi-lead diagnostic function due to the cumbersome equipment.

3. "Stability crisis" in extreme environments: "tampering" with signals by temperature

The temperature drift coefficient of consumer-grade ADC is more than 10μV/℃ at-20℃, and the baseline drift can reach 0.5mV in high temperature environment. In the emergency scene of northern winter, due to signal drift, the misjudgment rate of AED equipment for ventricular fibrillation waveform may increase by 50%.

2、The way to break the game: CBM24AD98Q Technological innovation

1, 24, high precision

CBM24AD98Q Utilizing a 24-bit Δ-Σ architecture, this device employs oversampling and noise shaping techniques, along with a 1-24x programmable gain (PGA), to achieve precise quantization of microvolt-level bioelectric signals. It can detect minute voltage fluctuations in bioelectric signals, such as the microvolt-level P waves and T waves found in electrocardiograms (ECG).

2. Ultra-low input reference noise

At a bandwidth of 150Hz and a gain of 6, the input reference noise is as low as 4μVpp, which is the same level as similar products. However, by optimizing the circuit design, the low noise performance can still be maintained at a higher gain (24 times), which is suitable for scenarios with very low signal strength such as electromyography (EMG).

3. High common mode rejection ratio (CMRR)

-115dB CMRR effectively suppresses ambient electromagnetic interference (such as high-frequency noise in medical devices) to ensure that pure bioelectrical signals can be obtained in complex clinical environments. For example, in the operating room, the chip can effectively isolate high-frequency electrocautery interference and ensure the integrity of the electrocardiogram waveform.

4. Built-in multi-functional analog front end

It integrates 8 programmable gain amplifiers (PGAs), right leg drive (RLD) circuits, lead detachment detection, and Wilson Center End (WCT) generation modules, enabling standard 12-lead ECG acquisition without the need for external operational amplifiers. Compared to traditional solutions, it reduces peripheral components by approximately 30%, thereby reducing PCB area and system costs.

5. Flexible signal processing architecture

Each channel supports an independent input multiplexer, which can be configured as either differential or single-ended input. It also features a built-in test signal generator for system calibration and fault diagnosis. For example, in a dynamic electrocardiogram device, the built-in lead detachment detection function allows real-time monitoring of electrode contact status, preventing data loss.

6. Multi-chip cascading capability

Through the SPI interface, the chrysanthemum chain can be cascaded to expand to 64-channel synchronous acquisition, which meets the needs of high-end multi-parameter monitors for simultaneous monitoring of multiple physiological signals (such as ECG, EEG, respiratory impedance). This scalability makes CBM24AD98Q a core component of high-end medical equipment.

7. Product features

l Up to 8 low noise PGA and 8 high resolution synchronous sampling ADC

l Input reference noise: 4 μVPP (150Hz BW, G=6)

l Input bias current: 200 pA

l Data rate: 250 SPS to 32kSPS

l Common-mode rejection ratio: -115 dB

l Programmable gain: 1, 2, 4, 6, 8, 12 or 24

l Single or double pole power supply:

• Simulation: 2.7V to 5.5V

• Digital: 1.7V to 3.3V

l Built-in right leg drive amplifier, lead detection, test signal

l Built-in Wilson center terminals and enhanced electrode circuit

l Built-in clock oscillator, optional internal or external clock

l Built-in voltage reference, optional internal or external reference

l Flexible power off and standby mode

l Compatible with ADS1298 pin and program

l SPI compatible serial interface

l Operating temperature range: -40°C to +85°C

3、Full scene penetration: "core" infrastructure from clinical diagnosis to cutting-edge research

1. Clinical diagnosis: the cornerstone of precision

CBM24AD98Q provides a 'miniaturized heart' for 12-lead ECG machines, where a single chip can generate standard 12-lead signals. This not only simplifies the complexity of external circuits but also significantly reduces the misdiagnosis rate by 45%. For multi-lead EEG devices, the 8-channel synchronous sampling capability can capture smaller electrical signals, reducing the localization error of epileptic foci from 10mm to 5mm, thus providing more precise navigation for neurosurgical procedures.

2. Wearable devices: Long-lasting "invisible guardians"

In the field of dynamic electrocardiogram monitoring, 17.5mW's ultra-low power consumption mode has significantly extended the battery life of Holter devices from 4 to 7 days, while also boosting the data integrity rate from 85% to 99%. With a single-lead design, the device can be reduced to the size of a coin, making it ideal for elderly individuals at home for health monitoring. In the field of sleep medicine, the Daisy Chain Cascade technology supports 32-channel synchronous data collection, allowing a single device to cover multiple parameters such as EEG, EMG, and respiratory impedance, aiding in the precise classification of sleep apnea syndrome.

3. First aid and extreme environments: the "ultimate challenge" of reliability

For outdoor emergency scenarios, the-40℃ cold start feature enables the AED device to respond quickly even in the snowy regions of Northeast China. The device's stable operation at 85℃ high temperatures ensures its availability around the clock in tropical regions. According to statistics from a border hospital, the introduction of advanced chip technology has significantly reduced the winter failure rate of the on-board ECG device from 25% to 5%. Additionally, the emergency response efficiency has increased by 40%.