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英国普莱赛公司研制了低噪声 InP 反射型放大器,在15千兆赫下在1千兆赫带宽范围内,其增益为8分贝。器件结构为 n~÷-n-n~÷夹层结构,外延层厚度为2微米,掺杂浓度为10~(13)厘米~(-3),并具有集成热沉。当频率从12千兆赫变到18千兆赫时,将偏压调到最佳,可使噪声系数在8～9分贝间,其变化小于1分贝。发现噪声系数是外延层掺杂浓度的函数,对于10~(12)厘米~(-3)的载流子浓度,噪声系数渐近地趋近于7～8分贝。
Plessey has developed a low-noise InP reflective amplifier with a gain of 8 dB at 15 GHz in the 1 GHz bandwidth. The device structure is n ~ ÷ -n-n ~ ÷ sandwich structure, epitaxial layer thickness of 2 microns, doping concentration of 10 ~ (13) cm ~ (-3), and has an integrated heat sink. When the frequency changes from 12 gigahertz to 18 gigahertz, the bias voltage is tuned to the best, resulting in a noise figure of between 8 and 9 dB, which varies by less than 1 dB. The noise figure is found to be a function of the doping concentration of the epitaxial layer. For a carrier concentration of 10 ~ (12) cm ~ (-3), the noise figure approaches asymptotically 7 ~ 8 dB.