ABSTRACT The field of weak current detection faces critical challenges, as conventional resistive feedback trans‐impedance amplifiers (R‐TIAs) struggle with the integration of on‐chip high‐value resistors and suffer from bandwidth degradation due to parasitic capacitance in off‐chip configurations and process‐voltage‐temperature (PVT) variations. To address these issues, a new proportional R‐TIA based on proportional two‐parallel pseudo‐resistors is proposed in this paper, where the proportional characteristic of pseudo‐resistors is used to amplify the effective impedance of low‐value resistors. This design not only suppresses PVT variations but also enhances the linearity, obviating the need for extra compensation modules that add complexity to conventional schemes. Fabricated in a 55‐nm CMOS process, the proposed R‐TIA achieves a trans‐impedance gain of 181.33 dB, a bandwidth of 10.10 kHz (covering typical signal frequencies in biomedical sensing), and an equivalent input noise of 0.37 pA, enabling efficient weak current‐to‐voltage conversion. Total harmonic distortion (THD) remains below 1% before the output reaches full scale. Compared with existing pseudo‐resistor‐based R‐TIAs, it reduces circuit complexity and parasitic‐induced performance loss while retaining high performance, making it well‐suited for weak current sensing in electrochemical and biomedical applications.
Wang et al. (Mon,) studied this question.