Abstract
<title>Abstract</title> <p>In high-speed optical receivers, the transimpedance amplifier (TIA), as the first analog block, plays a critical role in converting the weak photodiode current into a processable voltage while providing the required bandwidth, low-noise, and low-power consumption. In this paper, a low-power TIA based on a regulated cascode (RGC) structure is designed for 40 Gbps optical applications using 32 nm carbon nanotube field-effect transistor (CNTFET) technology. In the proposed topology, the transconductance of the driver transistor is enhanced through gain boosting, while a diode-connected configuration is employed at the output node to reduce the effective output-node resistance, decrease the associated time constant, and extend the frequency response. Simulations based on the Stanford CNTFET model demonstrate that the proposed circuit achieves a transimpedance gain of 51.4 dBΩ, a − 3 dB bandwidth of 28.3 GHz, an input-referred noise current of 5.3 pA/√Hz, and a power consumption of 368 µW. These results indicate that the proposed structure can be considered a suitable candidate for low-power TIA implementation in 40 Gbps optical receivers.</p>