Modulation bandwidth and noise limit of photoconductive gates
Autor: | J. F. Whitaker, H. Cheng, Jiunn-Ren Hwang, J. V. Rudd |
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Rok vydání: | 1996 |
Předmět: |
Materials science
business.industry Transistor Bandwidth (signal processing) JFET Hardware_PERFORMANCEANDRELIABILITY Input impedance Laser Atomic and Molecular Physics and Optics Electronic Optical and Magnetic Materials law.invention Parasitic capacitance law Temporal resolution Hardware_INTEGRATEDCIRCUITS Optoelectronics Laser power scaling Electrical and Electronic Engineering business Telecommunications Hardware_LOGICDESIGN |
Zdroj: | Optical and Quantum Electronics. 28:961-973 |
ISSN: | 1572-817X 0306-8919 |
DOI: | 10.1007/bf00820161 |
Popis: | The modulation bandwidth and noise limit of a photoconductive sampling gate are studied by reducing the parasitic capacitance and leakage current of the sampling circuit using an integrated junction field-effect transistor (JFET) source follower. The modulation bandwidth of the photoconductive sampling gate is limited by the external parasitic capacitance, and its efficiency is found to saturate at a laser gating power of about 1 mW. It is determined that the noise of the photoconductive sampling gate is dominated by the photovoltaic current due to the gating laser amplitude fluctuation. A minimum noise level of 4 nV Hz -1/2 has been measured, and an enhancement in signalto-noise ratio by a factor of >45 has been achieved after the integration of the source follower with the photoconductive sampling gate. The JFET source follower serves to increase the modulation bandwidth of the photoconductive sampling gate by about 15 times and buffer the charge of the measured signal using its extremely high gate input impedance. The performance of the photoconductive sampling gate in regard to invasiveness and gating efficiency has been optimized, while a picosecond temporal resolution has been maintained and the signal-to-noise performance has been enhanced using a gating laser power as low as 10 #W. |
Databáze: | OpenAIRE |
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