The HXR45400 is an extension of a low-power, single-ended input, quad-channel linear Trans-Impedance Amplifier (TIA) array, and a member of the Optical Receiver Transmitter Array (ORTA) product family. Together with an array of PIN detectors or a group of detectors, the HXR45400 can be used to design a compact linear Receiver Optical Sub-Assembly (ROSA) for the next generation 400G/800G optical transceivers with advanced modulation schemes. The HXR45400 supports 53GBaud PAM4 applications. This TIA operates in a 3.3V supply or a 2.9V supply for low power consumption, providing exceptionally low input referred noise density, wide input optical power range, excellent linearity up to 3mA overload, and a high bandwidth. The chip is designed with the patented adaptive biasing scheme.