Single-channel 24-bit ADC GX1291 Compatible with ADS1291 for Portable Heart Rate Monitor

The heart rate map is a comprehensive representation of the heart‘s electrical activity on the body surface, so real-time heart rate monitoring is essential. The heart rate monitor is based on the premise of accurate detection, portable and low-power consumption, which requires the use of the smallest possible and high-performance devices, and the design of the smallest highly accurate low-power circuits. And through the Bluetooth module to transmit to the cell phone that everyone now has and has been using for a long time for ECG waveform and heart rate display, easy to use.

In a portable heart rate monitoring system, the higher the low power consumption and stability of the system, the better the user experience. Therefore, the hardware of the system should be streamlined as much as possible and a low-power chip should be selected. The system hardware mainly consists of a front-end circuit module to collect the human body‘s ECG signals, and carry out appropriate amplification and filtering to extract the weak ECG signals, and then convert the analog voltage signals into digital signals through the AD sampling function.

Because the analog signal is converted to a digital signal, and then data processing, so AD sampling is very important. The GX1291, a low-power, single-channel, 24-bit bioelectrical measurement front-end analog chip, integrates all the features of a portable, low-power heart rate application with fast conversion rates and accurate sampling values. The chip has a built-in single-channel 24-bit Delta-Sigma (ΔΣ) analog-to-digital converter, a programmable gain amplifier, an internal reference and an oscillator, which effectively overcomes the drift and noise interference of the measurement signals and improves the measurement accuracy.

Application advantages in GX1291 heart rate monitor:

-Low power consumption 420μW;

- Input reference noise: 8μVPP (150Hz BW, G=6); input bias current: 200pA;

- Data rate: 125SPS to 16kSPS; Common mode rejection ratio CMRR: 120dB;

- Programmable Gain: 1, 2, 3, 4, 6, 8, 12, 16, 24, 32, 64, 96;

- Oscillator initial accuracy: ±0.5% (25℃), temperature drift ±1% (-40℃~85℃);

- Unipolar power supply: analog: 2.7V to 3.6V; digital: 1.7V to 3.6V;

- Built-in right leg drive amplifier, lead detection and test signal, built-in pacing signal output and detection circuit;

- Flexible conversion between low-power mode and standby mode, SPI-compatible serial interface;

- Operating temperature range: -40℃ to 125℃;

The GX1291 has a flexible input multiplexer that can be independently connected to internally generated signals for test, temperature, and disconnection detection; it has a data rate of up to 16kSPS and added PACE detection. Using the GX1291 as a front-end analog can streamline the design and size of hardware circuits, effectively reducing design costs.