The basic principle of an electronic sphygmomanometer is to use a pressure sensor to detect vibration changes in blood flow, and outputs to the MCU for algorithmic processing to obtain the blood pressure value. However, the output signal of the pressure sensor is relatively weak and requires a precision operational amplifier to handle it.

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The output signal of the electronic sphygmomanometer sensor is very weak, so the front-end signal amplification is a very big challenge which asked the offset voltage and temperature drift characteristics of the amplifier to be as small as possible. Since the electronic sphygmomanometer is battery-powered, the power consumption of the amplifier is required to be low enough. For electronic sphygmomanometer sensor output signal amplification applications, we recommend the domestic precision op amp RS8538 of Runic, which adopts CMOS process, rail-to-rail input and output, with high Gain-Bandwidth Product of 1.6MHz and an offset voltage as low as 1uV.

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For single power supply or dual power supply from +2.5V (±1.25V) to +5.5V (±2.75V), the following is the electrical characteristic and Pin diagram of RS8538 precision op amp:

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Electronic sphygmomanometers generally use piezoresistive sensors to measure blood?

vibration and output weak analog signals. If the op amp has a large inpiut offset voltage, it will cover up the real measurement signal. The RS8538 offset voltage is only 1uV, which can minimize the interference of the op amp itself to the measurement signal. The temperature drift of Vos is 0.005uV/?C, which improves the accuracy and reliability of blood pressure measurement. Electronic sphygmomanometers is battery-powered and strictly requires low system power consumption. The operating current of RS8538 is 340uA, and the low-power operational amplifier can extend the service life of the device.

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In summary, Runic's single-channel high-precision operational amplifier RS8538 has the advantages of low input offset voltage, low Vos temperature drift and low power consumption. At the same time, it is lower in cost. It is indeed a cost-effective solution used to amplify the sensor output signal in medical portable equipment such as electronic blood pressure monitors.