Resonant p-i-n-FET receivers for lightwave subcarrier systems

A theoretical and experimental analysis of narrowband resonant direct-detection p-i-n-FET receivers for subcarrier multiple-access networks is described. It is shown how a small inductance can be used to optimize the coupling between the p-i-n and FET, over a range of microwave subcarrier frequencies, minimizing the frequency-dependent thermal noise and leaving shot-noise as the ultimate limitation. Shot-noise then establishes a fixed ratio of the total usable bandwidth to the minimum received power per channel, which for the binary FSK system considered is 6.1 GHz/ mu mW. A resonant p-i-n-FET receiver, designed to provide maximum sensitivity between 2.5 and 5.0 GHz, has been constructed. The measured signal-to-noise ratio is in excellent agreement with that predicted by the noise analysis.<
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