Noise Characteristics of Long-Wavelength Monolithically Integrated Pin-FETs.

The noise characteristics of a monolithically integrated pin-FET were analyzed using the circuit simulator SPICE This device consists of InGaAs p-i-n photodiodes (PDs) and InGaAs-channel junction field-effect transistors (JFETs). The equation for the metal-semiconductor field- effect transistor (MESFET) model of the SPICE simulator is modified to fit the noise characteristics of the fabricated InGaAs channel WETs. Then the noise parameters are extracted by fitting the simulation results to the measured noise characteristics of the pin-FET. The sensitivity degradation caused by the noise from the two noise sources in the monolithic pin-FETs is analyzed by circuit simulations using these noise parameters. The noise sources considered in this analysis are the load FET at the common-source amplifier stage and the level-shift diodes introduced to provide the operation with a single power supply. Finally, the measured sensitivity differences among the channels of the fabricated four-channel pin-FET any are analyzed and it is shown that they agree with the simulation results when the flicker noise is proportional to 1/f0.8 where f is the frequency. This simulation technology is useful for analyzing the noise factors that dominate the noise characteristics and can be used to predict the sensitivity when designing monolithic photo- receivers. [ABSTRACT FROM AUTHOR]