Fjarlie E J
Appl Opt. 1977 Feb 1;16(2):385-92. doi: 10.1364/AO.16.000385.
Positive feedback circuits have been developed that allow an NEP (1.42, 500, 1) of 10(-14) W Hz(-(1/2)) or better to be achieved for cooled intrinsic germanium photodiodes of up to 6-mm diam. These circuits have also been tested at room temperature with silicon photodiodes and with test capacitors; it is reasonable to suppose that they may be used with other transducers that have a capacitance as their dominant circuit component. Circuits that had one-half-power frequencies of 2-3 Hz with no feedback have routinely achieved bandwidth enhancement factors larger than 400 without degrading the original NEP. The technique is not limited to low frequency.
已经开发出正反馈电路，对于直径达6毫米的冷却本征锗光电二极管，该电路可实现10^(-14)W Hz^(-1/2)或更好的等效噪声功率（NEP，1.42, 500, 1）。这些电路还在室温下用硅光电二极管和测试电容器进行了测试；可以合理推测，它们可与以电容作为主要电路元件的其他换能器一起使用。在没有反馈时半功率频率为2 - 3Hz的电路，通常能在不降低原始等效噪声功率的情况下实现大于400的带宽增强因子。该技术不限于低频。
