A Novel High-Gain Low-Corner-Frequency Cascode Amplifier in IZO TFTs Using a Dynamic-Biased Dual-Capacitor Bootstrap Load for Bio-Signal Sensing

In this paper, we present a novel dual-capacitor bootstrap load amplifier structure. By integrating a dynamic bias network that enhances the resistance of cutoff-region transistors, this improved load configuration achieves a lower low-frequency high-pass corner compared to conventional structures while utilizing smaller bootstrap capacitors, thereby significantly reducing area occupation and ensuring the efficient transmission of critical low-frequency components in bioelectrical signals. Furthermore, negative capacitance compensation is employed to introduce left-half-plane zeros, for thereby improving phase margin and closed-loop stability. During the design of the proposed amplifier, the existing high-gain unipolar cascode amplifier–specifically, the dual-capacitor bootstrap load amplifier–was analyzed from a fresh perspective, emphasizing the interplay between its gain, low-frequency high-pass corner, and the capacitor bootstrap network. The implemented amplifier circuit using this load structure was fabricated using$10~\mu $m n-type IZO TFT technology. Experimental results confirm a voltage gain of 41 dB, a low-frequency high-pass corner frequency of 0.5 Hz, an area occupation of 3.81 mm2, and a power consumption of 0.27mW, thus validating the significant application potential of the proposed architecture in flexible sensing and biosignal acquisition domains.