Fast calculation of transimpedance gain and equivalent input noise current density for high-speed optical preamplifier design

Analytical expressions for the relationships between the transimpedance gain and S-parameters, equivalent input noise current density and noise figure for high-speed optical transimpedance amplifier design are proposed in this article. This technique is based on the signal and noise equivalent circuit models of the optical transimpedance preamplifier. The transimpedance gain and equivalent input noise current density can be obtained directly from measured S-parameters and noise figure, without any additional measurement equipment. A 10 Gb/s high electron mobility transistor (HEMT)-based transimpedance preamplifier has been designed and the measured S-parameters and noise figure have been used to demonstrate this approach.