金属氧化物薄膜晶体管（MO-TFT）可以用来实现检测心率信号的柔性可穿戴系统，但MO-TFT缺少高性能互补器件，导致实现的前置放大器增益较小，而且MO-TFT器件的性能较差，给后级模块的设计带来了困难。为提升前置放大器的增益，降低后级电路对器件性能的要求，该文提出了一种共源共栅电容自举结构前置放大器。该前置放大器主要由外部耦合偏置模块和核心放大器模块构成；核心放大器模块使用稳定性好、输出电压摆幅大和功耗低的电容自举技术，并结合了共源共栅结构，以提升电路的整体增益；外部耦合偏置模块使用功耗较低、输入阻抗较大和工作点设置简单的交流耦合外部偏置结构，以满足心率信号检测前置放大器的带通要求。采用10 μm IZO-TFT工艺对所提出的前置放大器进行设计和流片测试，结果表明：在20 V电源电压条件下，该放大器的增益为35 dB，带宽为2 Hz~2 kHz，噪声均方根值为118.2 μV，功耗为0.1 mW，实现的前置放大器满足心率信号检测要求；与现有的MO-TFT心率信号检测前置放大器相比，所设计的前置放大器增益提升了约10 dB，降低了后级模块对器件性能的要求，有利于实现模拟信号的数字化，保持信号的完整性。

Metal-oxide thin-film transistor (MO-TFT) can be utilized to create a flexible wearable system for detec-ting heart rate signals. However, the lack of high-performance complementary devices in MO-TFTs results in low gain for the implemented preamplifiers. Additionally, the relatively poor performance of MO-TFT devices poses challenges for the design of subsequent modules. In order to improve the gain of the preamplifier and reduce the performance requirements of the subsequent digital circuit, this paper proposed a common source common gate capacitor bootstrap structure preamplifier. The preamplifier was mainly composed of an external coupling bias module and a core amplifier module. The core amplifier module uses a capacitor bootstrapping technique known for its excellent stability, large output voltage swing, and low power consumption. This technique is combined with a cascode structure to enhance the overall gain of the circuit. The external coupling bias module utilizes an AC-coupled external bias structure that features low power consumption, high input impedance, and straightforward operating point setting, thereby meeting the bandpass requirements of the preamplifier for heart rate signal detection. The proposed preamplifier was designed and fabricated using a 10 μm IZO-TFT process. The test results indicate that with a 20 V power supply voltage, the circuit has a gain of 35 dB, a bandwidth of 2 Hz~2 kHz, a noise of 118.2 μV, and a power consumption of 0.1 mW. The presented preamplifier meets the requirements for detecting heart rate signals. In comparison to the current MO-TFT heart rate signal detection preamplifier, the gain has been increased by about 10 dB, which reduces the performance requirements of the subsequent digital module on the device, and is beneficial to achieve the digitalization of analog signals and maintain the signal integrity.