GXSC AFE Replaces ADS1298 in Multimodal Brain Function Instrument

The multimodal brain function instrument innovatively integrates electroencephalography (EEG) and near-infrared technology. Through an integrated cap design, it achieves precise, coordinated arrangement of electrode and optical array arrays. Equipped with an internal synchronous clock source, it generates a unified timing reference to ensure millisecond-level time alignment between EEG and near-infrared data. This enables the simultaneous capture of neurophysiological activity and regional cerebral hemodynamic changes, providing a comprehensive observation solution for brain function.

 

Neurophysiological signals are characterized by weak amplitude, low signal-to-noise ratio, susceptibility to power-line interference, narrow signal bandwidth, and strict multi-channel timing requirements. Conventional ADC chips struggle to capture subtle changes in brain waves. The GXSC 8-channel 24-bit physiological signal acquisition analog front-end is specifically designed for the synchronous acquisition of multi-channel bioelectric signals such as EEG, ECG, and EMG, making it the mainstream core chip for current multimodal EEG devices.

 

The GXSC AFE includes a programmable gain amplifier, an analog-to-digital converter, an internal reference, an oscillator, lead disconnection detection, and a right-leg drive amplifier. It eliminates the need for complex front-end conditioning circuits, significantly simplifying the hardware design of EEG monitoring devices, reducing PCB footprint, and meeting the miniaturization requirements of portable devices. Its programmable gain ranges from 1, 2, 3, 4, 6, 8, to 12, allowing flexible adjustment based on EEG signal amplitude to ensure signals remain within the optimal acquisition range.

 

Key features of the GXSC AFE chip are as follows:

• Data rate: 31.25 SPS to 32 kSPS

• Programmable gain: 1, 2, 3, 4, 6, 8, or 12

• Ultra-low input reference noise: 4.07 μVpp (0.64 μVrms) (BW=150 Hz, G=6)

• CMRR: 120 dB

• Flexible power modes: High-Speed (HS), Low-Power (LP), and Ultra-Low-Power (ULP)

• In Low-Power mode, power consumption is only 410 µW (AVDD = 3 V, DVDD = 1.8 V, ODR = 500 SPS, G = 6)

• Integrated low-drift reference; integrated clock with adjustable frequency and external output capability

• Integrated right-lead drive amplifier, lead disconnection detection, temperature sensor, and test signal

• Supports digital pacing detection

• Adjustable data buffer depth (1/2/4/8/16/32)

• Offset/Gain error calibration function

• Power supply range: Analog power supply: 2.7V to 5.25V; Digital power supply: 1.8V to 5.25V

• Flexible power-down and standby modes

• SPI interface

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