A low-noise CMOS image sensor (CIS) with intra-scene high-dynamic-range (HDR) feature is presented. The design employs in-pixel 5-transistor (5T) operational transconductance amplifier (OTA) in open-loop configuration to achieve high gain to amplify a weak signal under low illumination. A unity-gain configuration is adopted for high level illumination, and it can avoid saturation at the output, thereby enhancing the overall dynamic range. Noise suppression is further enhanced through analog correlated double sampling (CDS) in the column programmable gain amplifier (PGA) and digital CDS after analog-to-digital conversion, effectively suppressing kT/C noise, low-frequency noise and offset. A prototype was developed using 180 nm CIS process, and the characterization results show that the sensor has a low input-referred noise of 0.67 e−r ms and dynamic range of 80 dB. The proposed approach provides a practical path toward low-noise, widedynamic-range CIS architectures and can be extended to future pixel-parallel readout schemes.