24 bit 32kSPS analog front-end chip GX1291 software and hardware 100% replacement of ADS1291 in smart wristbands application

At present, smart wristband products on the market have upgraded from basic step counting functions to health monitoring. The functions include real-time collection of bioelectric signals such as heart rate, blood oxygen saturation, electrocardiogram (ECG), etc., which can provide services such as cardiovascular health assessment and sleep quality analysis for smart wristband users. Usually, the small frequency of biological signals is concentrated in 0.05Hz~100Hz, and the collection process is easily affected by human movement, electromagnetic radiation, and skin contact noise. This article recommends replacing ADS1291 with a simulated front-end chip GX1291 for application in smart wristbands.

GX1291 is designed specifically for biological potential measurement, with 100% replacement of ADS1291 in software and hardware. It supports 24 bit high resolution and can finely quantify weak biological signals. At the same time, it adopts advanced low-noise design, with internally integrated programmable gain amplifier (PGA) and digital filter, which can effectively suppress noise interference.

For portable battery products for smart bracelets, the GX1291 chip provides ULP mode, greatly improving battery life. Its data caching function can reduce the number of MCU interrupts, helping to save system power consumption. So choosing GX1291 can significantly reduce the size, power consumption, and cost of application products. And it has lead detection function based on excitation current trap/current source, with a current range of 6nA~399nA, which can be selected and adjusted according to product requirements.

In addition, the output data rate of GX1291 is as high as 32kSPS, which enables digital pacing detection. It has very low input reference noise during operation, and at GAIN=12, the input reference noise can be as low as 0.20 µ Vrms (1.24 µ Vpp). The common mode rejection ratio (CMRR) is not less than 120dB in unity gain mode. In addition, GX1291 still has an SNR of 87dB at an output rate of 32kSPS, demonstrating excellent performance.

The main features of GX1291 are as follows:

Data rate: 31.25SPS to 32kSPS

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

• Ultra low input reference noise: 4.07 μ Vpp (0.64 μ Vrms) (BW=150Hz, G=6)

• CMRR：120dB

Flexible power consumption modes: High Speed Mode (HS), Low Power Mode (LP), Ultra Low Power Mode (ULP)

Low power mode, with a power consumption of only 410 µ W (AVDD=3V, DVDD=1.8V, ODR=500SPS, G=6)

• Built in low-temperature float benchmark; Built in clock, capable of external output, and adjustable frequency

• Built in right leg driver amplifier, lead detachment detection, temperature sensor, test signal

• Supports digital pacing detection

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